Hemolysin Proteins
Hemolysis
Streptococcus bovis
Enterococcus
Enterococcus faecalis
Streptococcus
Gram-Positive Bacterial Infections
Language Arts
Gram-Positive Cocci
Streptococcus pyogenes
Pharynx
Gases
Alpha-toxin and gamma-toxin jointly promote Staphylococcus aureus virulence in murine septic arthritis. (1/3113)
Septic arthritis is a common and feared complication of staphylococcal infections. Staphylococcus aureus produces a number of potential virulence factors including certain adhesins and enterotoxins. In this study we have assessed the roles of cytolytic toxins in the development of septic arthritis by inoculating mice with S. aureus wild-type strain 8325-4 or isogenic mutants differing in the expression of alpha-, beta-, and gamma-toxin production patterns. Mice inoculated with either an alpha- or beta-toxin mutant showed degrees of inflammation, joint damage, and weight decrease similar to wild-type-inoculated mice. In contrast, mice inoculated with either double (alpha- and gamma-toxin-deficient)- or triple (alpha-, beta-, and gamma-toxin-deficient)-mutant S. aureus strains showed lower frequency and severity of arthritis, measured both clinically and histologically, than mice inoculated with the wild-type strain. We conclude that simultaneous production of alpha- and gamma-toxin is a virulence factor in S. aureus arthritis. (+info)Evolutionary relationships of pathogenic clones of Vibrio cholerae by sequence analysis of four housekeeping genes. (2/3113)
Studies of the Vibrio cholerae population, using molecular typing techniques, have shown the existence of several pathogenic clones, mainly sixth-pandemic, seventh-pandemic, and U.S. Gulf Coast clones. However, the relationship of the pathogenic clones to environmental V. cholerae isolates remains unclear. A previous study to determine the phylogeny of V. cholerae by sequencing the asd (aspartate semialdehyde dehydrogenase) gene of V. cholerae showed that the sixth-pandemic, seventh-pandemic, and U.S. Gulf Coast clones had very different asd sequences which fell into separate lineages in the V. cholerae population. As gene trees drawn from a single gene may not reflect the true topology of the population, we sequenced the mdh (malate dehydrogenase) and hlyA (hemolysin A) genes from representatives of environmental and clinical isolates of V. cholerae and found that the mdh and hlyA sequences from the three pathogenic clones were identical, except for the previously reported 11-bp deletion in hlyA in the sixth-pandemic clone. Identical sequences were obtained, despite average nucleotide differences in the mdh and hlyA genes of 1.52 and 3.25%, respectively, among all the isolates, suggesting that the three pathogenic clones are closely related. To extend these observations, segments of the recA and dnaE genes were sequenced from a selection of the pathogenic isolates, where the sequences were either identical or substantially different between the clones. The results show that the three pathogenic clones are very closely related and that there has been a high level of recombination in their evolution. (+info)Role of Listeria monocytogenes exotoxins listeriolysin and phosphatidylinositol-specific phospholipase C in activation of human neutrophils. (3/3113)
Polymorphonuclear leukocytes (PMN) are essential for resolution of infections with Listeria monocytogenes. The present study investigated the role of the listerial exotoxins listeriolysin (LLO) and phosphatidylinositol-specific phospholipase C (PlcA) in human neutrophil activation. Different Listeria strains, mutated in individual virulence genes, as well as purified LLO were used. Coincubation of human neutrophils with wild-type L. monocytogenes provoked PMN activation, occurring independently of phagocytosis events, with concomitant elastase secretion, leukotriene generation, platelet-activating factor (PAF) synthesis, respiratory burst, and enhanced phosphoinositide hydrolysis. Degranulation and leukotriene formation were noted to be solely dependent on LLO expression, as these features were absent when the LLO-defective mutant EGD- and the avirulent strain L. innocua were used. These effects were fully reproduced by a recombinant L. innocua strain expressing LLO (INN+) and by the purified LLO molecule. LLO secretion was also required for PAF synthesis. However, wild-type L. monocytogenes was more potent in eliciting PAF formation than mutants expressing LLO, suggesting the involvement of additional virulence factors. This was even more obvious for phosphoinositide hydrolysis and respiratory burst: these events were provoked not only by INN+ but also by the LLO-defective mutant EGD- and by a recombinant L. innocua strain producing listerial PlcA. We conclude that human neutrophils react to extracellularly provided listerial exotoxins by rapid cell activation. Listeriolysin is centrally involved in triggering degranulation and lipid mediator generation, and further virulence factors such as PlcA apparently contribute to trigger neutrophil phosphoinositide hydrolysis and respiratory burst. In this way, listerial exotoxins may influence the host defense against infections with L. monocytogenes. (+info)Vibrio parahaemolyticus thermostable direct hemolysin modulates cytoskeletal organization and calcium homeostasis in intestinal cultured cells. (4/3113)
Vibrio parahaemolyticus is a marine bacterium known to be the leading cause of seafood gastroenteritis worldwide. A 46-kDa homodimer protein secreted by this microorganism, the thermostable direct hemolysin (TDH), is considered a major virulence factor involved in bacterial pathogenesis since a high percentage of strains of clinical origin are positive for TDH production. TDH is a pore-forming toxin, and its most extensively studied effect is the ability to cause hemolysis of erythrocytes from different mammalian species. Moreover, TDH induces in a variety of cells cytotoxic effects consisting mainly of cell degeneration which often leads to loss of viability. In this work, we examined the cellular changes induced by TDH in monolayers of IEC-6 cells (derived from the rat crypt small intestine), which represent a useful cell model for studying toxins from enteric bacteria. In experimental conditions allowing cell survival, TDH induces a rapid transient increase in intracellular calcium as well as a significant though reversible decreased rate of progression through the cell cycle. The morphological changes seem to be dependent on the organization of the microtubular network, which appears to be the preferential cytoskeletal element involved in the cellular response to the toxin. (+info)Hyperproduction of alpha-hemolysin in a sigB mutant is associated with elevated SarA expression in Staphylococcus aureus. (5/3113)
To evaluate the role of SigB in modulating the expression of virulence determinants in Staphylococcus aureus, we constructed a sigB mutant of RN6390, a prototypic S. aureus strain. The mutation in the sigB gene was confirmed by the absence of the SigB protein in the mutant on an immunoblot as well as the failure of the mutant to activate sigmaB-dependent promoters (e.g., the sarC promoter) of S. aureus. Phenotypic analysis indicated that both alpha-hemolysin level and fibrinogen-binding capacity were up-regulated in the mutant strain compared with the parental strain. The increase in fibrinogen-binding capacity correlated with enhanced expression of clumping factor and coagulase on immunoblots. The effect of the sigB mutation on the enhanced expression of the alpha-hemolysin gene (hla) was primarily transcriptional. Upon complementation with a plasmid containing the sigB gene, hla expression returned to near parental levels in the mutant. Detailed immunoblot analysis as well as a competitive enzyme-linked immunosorbent assay of the cell extract of the sigB mutant with anti-SarA monoclonal antibody 1D1 revealed that the expression of SarA was higher in the mutant than in the parental control. Despite an elevated SarA level, the transcription of RNAII and RNAIII of the agr locus remained unaltered in the sigB mutant. Because of a lack of perturbation in agr, we hypothesize that inactivation of sigB leads to increased expression of SarA which, in turn, modulates target genes via an agr-independent but SarA-dependent pathway. (+info)Probing the function of Bordetella bronchiseptica adenylate cyclase toxin by manipulating host immunity. (6/3113)
We have examined the role of adenylate cyclase-hemolysin (CyaA) by constructing an in-frame deletion in the Bordetella bronchiseptica cyaA structural gene and comparing wild-type and cyaA deletion strains in natural host infection models. Both the wild-type strain RB50 and its adenylate cyclase toxin deletion (DeltacyaA) derivative efficiently establish persistent infections in rabbits, rats, and mice following low-dose inoculation. In contrast, an inoculation protocol that seeds the lower respiratory tract revealed significant differences in bacterial numbers and in polymorphonuclear neutrophil recruitment in the lungs from days 5 to 12 postinoculation. We next explored the effects of disarming specific aspects of the immune system on the relative phenotypes of wild-type and DeltacyaA bacteria. SCID, SCID-beige, or RAG-1(-/-) mice succumbed to lethal systemic infection following high- or low-dose intranasal inoculation with the wild-type strain but not the DeltacyaA mutant. Mice rendered neutropenic by treatment with cyclophosphamide or by knockout mutation in the granulocyte colony-stimulating factor locus were highly susceptible to lethal infection by either wild-type or DeltacyaA strains. These results reveal the significant role played by neutrophils early in B. bronchiseptica infection and by acquired immunity at later time points and suggest that phagocytic cells are a primary in vivo target of the Bordetella adenylate cyclase toxin. (+info)Resistance of paroxysmal nocturnal hemoglobinuria cells to the glycosylphosphatidylinositol-binding toxin aerolysin. (7/3113)
Paroxysmal nocturnal hemoglobinuria (PNH) is a clonal stem cell disorder caused by a somatic mutation of the PIGA gene. The product of this gene is required for the biosynthesis of glycosylphosphatidylinositol (GPI) anchors; therefore, the phenotypic hallmark of PNH cells is an absence or marked deficiency of all GPI-anchored proteins. Aerolysin is a toxin secreted by the bacterial pathogen Aeromonas hydrophila and is capable of killing target cells by forming channels in their membranes after binding to GPI-anchored receptors. We found that PNH blood cells (erythrocytes, lymphocytes, and granulocytes), but not blood cells from normals or other hematologic disorders, are resistant to the cytotoxic effects of aerolysin. The percentage of lysis of PNH cells after aerolysin exposure paralleled the percentage of CD59(+) cells in the samples measured by flow cytometry. The kinetics of red blood cell lysis correlated with the type of PNH erythrocytes. PNH type III cells were completely resistant to aerolysin, whereas PNH type II cells displayed intermediate sensitivity. Importantly, the use of aerolysin allowed us to detect PNH populations that could not be detected by standard flow cytometry. Resistance of PNH cells to aerolysin allows for a simple, inexpensive assay for PNH that is sensitive and specific. Aerolysin should also be useful in studying PNH biology. (+info)Localization and environment of tryptophans in soluble and membrane-bound states of a pore-forming toxin from Staphylococcus aureus. (8/3113)
The location and environment of tryptophans in the soluble and membrane-bound forms of Staphylococcus aureus alpha-toxin were monitored using intrinsic tryptophan fluorescence. Fluorescence quenching of the toxin monomer in solution indicated varying degrees of tryptophan burial within the protein interior. N-Bromosuccinimide readily abolished 80% of the fluorescence in solution. The residual fluorescence of the modified toxin showed a blue-shifted emission maximum, a longer fluorescence lifetime as compared to the unmodified and membrane-bound alpha-toxin, and a 5- to 6-nm red edge excitation shift, all indicating a restricted tryptophan environment and deeply buried tryptophans. In the membrane-bound form, the fluorescence of alpha-toxin was quenched by iodide, indicating a conformational change leading to exposure of some tryptophans. A shorter average lifetime of tryptophans in the membrane-bound alpha-toxin as compared to the native toxin supported the conclusions based on iodide quenching of the membrane-bound toxin. Fluorescence quenching of membrane-bound alpha-toxin using brominated and spin-labeled fatty acids showed no quenching of fluorescence using brominated lipids. However, significant quenching was observed using 5- and 12-doxyl stearic acids. An average depth calculation using the parallax method indicated that the doxyl-quenchable tryptophans are located at an average depth of 10 A from the center of the bilayer close to the membrane interface. This was found to be in striking agreement with the recently described structure of the membrane-bound form of alpha-toxin. (+info)Hemolysins are a type of protein toxin produced by certain bacteria, fungi, and plants that have the ability to damage and destroy red blood cells (erythrocytes), leading to their lysis or hemolysis. This results in the release of hemoglobin into the surrounding environment. Hemolysins can be classified into two main categories:
1. Exotoxins: These are secreted by bacteria and directly damage host cells. They can be further divided into two types:
* Membrane attack complex/perforin-like proteins (MACPF): These hemolysins create pores in the membrane of red blood cells, disrupting their integrity and causing lysis. Examples include alpha-hemolysin from Staphylococcus aureus and streptolysin O from Streptococcus pyogenes.
* Enzymatic hemolysins: These hemolysins are enzymes that degrade specific components of the red blood cell membrane, ultimately leading to lysis. An example is streptolysin S from Streptococcus pyogenes, which is a thiol-activated, oxygen-labile hemolysin.
2. Endotoxins: These are part of the outer membrane of Gram-negative bacteria and can cause indirect hemolysis by activating the complement system or by stimulating the release of inflammatory mediators from host cells.
Hemolysins play a significant role in bacterial pathogenesis, contributing to tissue damage, impaired immune responses, and disease progression.
Hemolysis is the destruction or breakdown of red blood cells, resulting in the release of hemoglobin into the surrounding fluid (plasma). This process can occur due to various reasons such as chemical agents, infections, autoimmune disorders, mechanical trauma, or genetic abnormalities. Hemolysis may lead to anemia and jaundice, among other complications. It is essential to monitor hemolysis levels in patients undergoing medical treatments that might cause this condition.
"Hemolysin factors" is not a standard medical term, and it seems there might be some confusion in the question. However, I can provide information on hemolysins, which are substances that cause lysis (rupture) of red blood cells, resulting in the release of their contents into the surrounding fluid.
Hemolysins can be produced by various sources, such as:
1. Bacterial hemolysins: Some bacteria produce hemolysins as a virulence factor to aid in infecting the host. These hemolysins can be classified into two main types: exotoxins (secreted by the bacterium) and endotoxins (integral components of the bacterial cell membrane). Examples include streptolysin O and streptolysin S from Streptococcus pyogenes, hemolysin from Escherichia coli, and α-toxin from Staphylococcus aureus.
2. Complement system: The complement system is a part of the immune response that can cause hemolysis through the membrane attack complex (MAC). This complex forms pores in the red blood cell membrane, leading to lysis.
3. Autoimmune disorders: In some autoimmune diseases, such as autoimmune hemolytic anemia, the body produces antibodies against its own red blood cells, causing complement-mediated hemolysis.
4. Medicines and chemicals: Certain medications or chemicals can cause hemolysis as a side effect. These include some antibiotics (e.g., cephalosporins), chemotherapeutic agents, and snake venoms.
If you meant to ask about something else related to "hemolysin factors," please provide more context so I can give a more accurate answer.
Streptococcus bovis is a type of bacteria that is part of the Streptococcus genus. It is a gram-positive, facultatively anaerobic coccus (spherical) bacterium that is commonly found in the gastrointestinal tracts of animals, including cattle, and can also be found in the human gastrointestinal tract, particularly in the colon.
There are several subspecies of Streptococcus bovis, including S. bovis biotype I (also known as Streptococcus gallolyticus), S. bovis biotype II/2, and S. bovis biotype II/1. Some strains of these bacteria have been associated with human diseases, such as endocarditis, bacteremia, and abscesses in various organs. Additionally, there is evidence to suggest that S. bovis biotype I may be associated with an increased risk of colorectal cancer.
It's important to note that Streptococcus bovis is not a common cause of infection in healthy individuals, but it can cause serious infections in people with underlying medical conditions, such as valvular heart disease or a weakened immune system.
Enterococcus is a genus of gram-positive, facultatively anaerobic bacteria that are commonly found in the intestinal tracts of humans and animals. They are part of the normal gut microbiota but can also cause a variety of infections, particularly in hospital settings. Enterococci are known for their ability to survive in harsh environments and can be resistant to many antibiotics, making them difficult to treat. Some species, such as Enterococcus faecalis and Enterococcus faecium, are more commonly associated with human infections.
In medical terms, an "Enterococcus infection" refers to an infection caused by any species of the Enterococcus genus. These infections can occur in various parts of the body, including the urinary tract, bloodstream, and abdominal cavity. They can cause symptoms such as fever, chills, and pain, depending on the location of the infection. Treatment typically involves the use of antibiotics that are effective against Enterococcus species, although resistance to multiple antibiotics is a growing concern.
Enterococcus faecalis is a species of gram-positive, facultatively anaerobic bacteria that are part of the normal gut microbiota in humans and animals. It is a type of enterococci that can cause a variety of infections, including urinary tract infections, bacteremia, endocarditis, and meningitis, particularly in hospitalized patients or those with compromised immune systems.
E. faecalis is known for its ability to survive in a wide range of environments and resist various antibiotics, making it difficult to treat infections caused by this organism. It can also form biofilms, which further increase its resistance to antimicrobial agents and host immune responses. Accurate identification and appropriate treatment of E. faecalis infections are essential to prevent complications and ensure positive patient outcomes.
Streptococcus is a genus of Gram-positive, spherical bacteria that typically form pairs or chains when clustered together. These bacteria are facultative anaerobes, meaning they can grow in the presence or absence of oxygen. They are non-motile and do not produce spores.
Streptococcus species are commonly found on the skin and mucous membranes of humans and animals. Some strains are part of the normal flora of the body, while others can cause a variety of infections, ranging from mild skin infections to severe and life-threatening diseases such as sepsis, meningitis, and toxic shock syndrome.
The pathogenicity of Streptococcus species depends on various virulence factors, including the production of enzymes and toxins that damage tissues and evade the host's immune response. One of the most well-known Streptococcus species is Streptococcus pyogenes, also known as group A streptococcus (GAS), which is responsible for a wide range of clinical manifestations, including pharyngitis (strep throat), impetigo, cellulitis, necrotizing fasciitis, and rheumatic fever.
It's important to note that the classification of Streptococcus species has evolved over time, with many former members now classified as different genera within the family Streptococcaceae. The current classification system is based on a combination of phenotypic characteristics (such as hemolysis patterns and sugar fermentation) and genotypic methods (such as 16S rRNA sequencing and multilocus sequence typing).
Gram-positive bacterial infections refer to illnesses or diseases caused by Gram-positive bacteria, which are a group of bacteria that turn purple when stained using the Gram stain method. This staining technique is used in microbiology to differentiate between two main types of bacteria based on their cell wall composition.
Gram-positive bacteria have a thick layer of peptidoglycan in their cell walls, which retains the crystal violet stain used in the Gram staining process. Some common examples of Gram-positive bacteria include Staphylococcus aureus, Streptococcus pyogenes, and Enterococcus faecalis.
Gram-positive bacterial infections can range from mild skin infections to severe and life-threatening conditions such as pneumonia, meningitis, and sepsis. The symptoms of these infections depend on the type of bacteria involved and the location of the infection in the body. Treatment typically involves the use of antibiotics that are effective against Gram-positive bacteria, such as penicillin, vancomycin, or clindamycin. However, the emergence of antibiotic resistance among Gram-positive bacteria is a growing concern and can complicate treatment in some cases.
I'm sorry for any confusion, but "Language Arts" is not a term used in medical definitions. Language arts is a term commonly used in education to refer to the academic study of reading, writing, speaking, and listening. It encompasses various subjects such as English, literature, grammar, creative writing, and communication skills. If you have any questions related to medical terminology or health-related topics, I would be happy to help with those!
"Gram-Positive Cocci" is a term used in microbiology, which refers to a specific type of bacteria that appear round (cocci) in shape and stain purple when subjected to the Gram staining method. The Gram staining technique is a fundamental laboratory method used to differentiate bacterial species based on their cell wall composition.
Gram-positive bacteria have a thick peptidoglycan layer in their cell walls, which retains the crystal violet stain used in the Gram staining process, resulting in a purple color. Some common examples of Gram-Positive Cocci include Staphylococcus aureus and Streptococcus pyogenes. These bacteria can cause various infections, ranging from skin and soft tissue infections to severe systemic illnesses. It is essential to identify the type and nature of bacterial pathogens accurately for appropriate antimicrobial therapy and effective patient management.
Streptococcus pyogenes is a Gram-positive, beta-hemolytic streptococcus bacterium that causes various suppurative (pus-forming) and nonsuppurative infections in humans. It is also known as group A Streptococcus (GAS) due to its ability to produce the M protein, which confers type-specific antigenicity and allows for serological classification into more than 200 distinct Lancefield groups.
S. pyogenes is responsible for a wide range of clinical manifestations, including pharyngitis (strep throat), impetigo, cellulitis, erysipelas, scarlet fever, rheumatic fever, and acute poststreptococcal glomerulonephritis. In rare cases, it can lead to invasive diseases such as necrotizing fasciitis (flesh-eating disease) and streptococcal toxic shock syndrome (STSS).
The bacterium is typically transmitted through respiratory droplets or direct contact with infected skin lesions. Effective prevention strategies include good hygiene practices, such as frequent handwashing and avoiding sharing personal items, as well as prompt recognition and treatment of infections to prevent spread.
Pharyngitis is the medical term for inflammation of the pharynx, which is the back portion of the throat. This condition is often characterized by symptoms such as sore throat, difficulty swallowing, and scratchiness in the throat. Pharyngitis can be caused by a variety of factors, including viral infections (such as the common cold), bacterial infections (such as strep throat), and irritants (such as smoke or chemical fumes). Treatment for pharyngitis depends on the underlying cause of the condition, but may include medications to relieve symptoms or antibiotics to treat a bacterial infection.
Streptococcal infections are a type of infection caused by group A Streptococcus bacteria (Streptococcus pyogenes). These bacteria can cause a variety of illnesses, ranging from mild skin infections to serious and potentially life-threatening conditions such as sepsis, pneumonia, and necrotizing fasciitis (flesh-eating disease).
Some common types of streptococcal infections include:
* Streptococcal pharyngitis (strep throat) - an infection of the throat and tonsils that can cause sore throat, fever, and swollen lymph nodes.
* Impetigo - a highly contagious skin infection that causes sores or blisters on the skin.
* Cellulitis - a bacterial infection of the deeper layers of the skin and underlying tissue that can cause redness, swelling, pain, and warmth in the affected area.
* Scarlet fever - a streptococcal infection that causes a bright red rash on the body, high fever, and sore throat.
* Necrotizing fasciitis - a rare but serious bacterial infection that can cause tissue death and destruction of the muscles and fascia (the tissue that covers the muscles).
Treatment for streptococcal infections typically involves antibiotics to kill the bacteria causing the infection. It is important to seek medical attention if you suspect a streptococcal infection, as prompt treatment can help prevent serious complications.
The pharynx is a part of the digestive and respiratory systems that serves as a conduit for food and air. It is a musculo-membranous tube extending from the base of the skull to the level of the sixth cervical vertebra where it becomes continuous with the esophagus.
The pharynx has three regions: the nasopharynx, oropharynx, and laryngopharynx. The nasopharynx is the uppermost region, which lies above the soft palate and is connected to the nasal cavity. The oropharynx is the middle region, which includes the area between the soft palate and the hyoid bone, including the tonsils and base of the tongue. The laryngopharynx is the lowest region, which lies below the hyoid bone and connects to the larynx.
The primary function of the pharynx is to convey food from the oral cavity to the esophagus during swallowing and to allow air to pass from the nasal cavity to the larynx during breathing. It also plays a role in speech, taste, and immune defense.
Streptococcal vaccines are immunizations designed to protect against infections caused by Streptococcus bacteria. These vaccines contain antigens, which are substances that trigger an immune response and help the body recognize and fight off specific types of Streptococcus bacteria. There are several different types of streptococcal vaccines available or in development, including:
1. Pneumococcal conjugate vaccine (PCV): This vaccine protects against Streptococcus pneumoniae, a type of bacteria that can cause pneumonia, meningitis, and other serious infections. PCV is recommended for all children under 2 years old, as well as older children and adults with certain medical conditions.
2. Pneumococcal polysaccharide vaccine (PPSV): This vaccine also protects against Streptococcus pneumoniae, but it is recommended for adults 65 and older, as well as younger people with certain medical conditions.
3. Streptococcus pyogenes vaccine: This vaccine is being developed to protect against Group A Streptococcus (GAS), which can cause a variety of infections, including strep throat, skin infections, and serious diseases like rheumatic fever and toxic shock syndrome. There are several different GAS vaccine candidates in various stages of development.
4. Streptococcus agalactiae vaccine: This vaccine is being developed to protect against Group B Streptococcus (GBS), which can cause serious infections in newborns, pregnant women, and older adults with certain medical conditions. There are several different GBS vaccine candidates in various stages of development.
Overall, streptococcal vaccines play an important role in preventing bacterial infections and reducing the burden of disease caused by Streptococcus bacteria.
In medical terms, gases refer to the state of matter that has no fixed shape or volume and expands to fill any container it is placed in. Gases in the body can be normal, such as the oxygen, carbon dioxide, and nitrogen that are present in the lungs and blood, or abnormal, such as gas that accumulates in the digestive tract due to conditions like bloating or swallowing air.
Gases can also be used medically for therapeutic purposes, such as in the administration of anesthesia or in the treatment of certain respiratory conditions with oxygen therapy. Additionally, measuring the amount of gas in the body, such as through imaging studies like X-rays or CT scans, can help diagnose various medical conditions.
Haemolysin expression modulating protein family