Marinomonas ostreistagni sp. nov., isolated from a pearl-oyster culture pond in Sanya, Hainan Province, China.
A Gram-negative, aerobic, halophilic, neutrophilic, rod-shaped, non-pigmented, polar-flagellated bacterium, UST010306-043(T), was isolated from a pearl-oyster culture pond in Sanya, Hainan Province, China in January 2001. This marine bacterium had an optimum temperature for growth of between 33 and 37 degrees C. On the basis of 16S rRNA gene sequence analysis, the strain was closely related to Marinomonas aquimarina and Marinomonas communis, with 97.5-97.7 and 97.1 % sequence similarity, respectively. Levels of DNA-DNA relatedness to the type strains of these species were well below 70 %. Analyses of phylogenetic, phenotypic and chemotaxomonic characteristics showed that strain UST010306-043(T) was distinct from currently established Marinomonas species. A novel species with the name Marinomonas ostreistagni sp. nov. is proposed to accommodate this bacterium, with strain UST010306-043(T) (=JCM 13672(T)=NRRL B-41433(T)) as the type strain. (+info)
A novel type of lysine oxidase: L-lysine-epsilon-oxidase.
The melanogenic marine bacterium M. mediterranea synthesizes marinocine, a protein with antibacterial activity. We cloned the gene coding for this protein and named it lodA [P. Lucas-Elio, P. Hernandez, A. Sanchez-Amat, F. Solano, Purification and partial characterization of marinocine, a new broad-spectrum antibacterial protein produced by Marinomonas mediterranea. Biochim. Biophys. Acta 1721 (2005) 193-203; P. Lucas-Elio, D. Gomez, F. Solano, A. Sanchez-Amat, The antimicrobial activity of marinocine, synthesized by M. mediterranea, is due to the hydrogen peroxide generated by its lysine oxidase activity. J. Bacteriol. 188 (2006) 2493-2501]. Now, we show that this protein is a new type of lysine oxidase which catalyzes the oxidative deamination of free L-lysine into 6-semialdehyde 2-aminoadipic acid, ammonia and hydrogen peroxide. This new enzyme is compared to other enzymes related to lysine transformation. Two different groups have been used for comparison. Enzymes in the first group lead to 2-aminoadipic acid as a final product. The second one would be enzymes catalyzing the oxidative deamination of lysine releasing H2O2, namely lysine-alpha-oxidase (LalphaO) and lysyl oxidase (Lox). Kinetic properties, substrate specificity and inhibition pattern show clear differences with all above mentioned lysine-related enzymes. Thus, we propose to rename this enzyme lysine-epsilon-oxidase (lod for the gene) instead of marinocine. Lod shows high stereospecificity for free L-lysine, it is inhibited by substrate analogues, such as cadaverine and 6-aminocaproic acid, and also by beta-aminopropionitrile, suggesting the existence of a tyrosine-derived quinone cofactor at its active site. (+info)
Structural and regulatory genes required to make the gas dimethyl sulfide in bacteria.
Dimethyl sulfide (DMS) is a key compound in global sulfur and carbon cycles. DMS oxidation products cause cloud nucleation and may affect weather and climate. DMS is generated largely by bacterial catabolism of dimethylsulfoniopropionate (DMSP), a secondary metabolite made by marine algae. We demonstrate that the bacterial gene dddD is required for this process and that its transcription is induced by the DMSP substrate. Cloned dddD from the marine bacterium Marinomonas and from two bacterial strains that associate with higher plants, the N(2)-fixing symbiont Rhizobium NGR234 and the root-colonizing Burkholderia cepacia AMMD, conferred to Escherichia coli the ability to make DMS from DMSP. The inferred enzymatic mechanism for DMS liberation involves an initial step in which DMSP is modified by addition of acyl coenzyme A, rather than the immediate release of DMS by a DMSP lyase, the previously suggested mechanism. (+info)
Involvement of a novel copper chaperone in tyrosinase activity and melanin synthesis in Marinomonas mediterranea.
Tyrosinase activity and melanin synthesis in the marine bacterium Marinomonas mediterranea in media with very low copper concentrations are dependent on the presence of a protein (PpoB2) that functions as a chaperone to deliver copper to tyrosinase (PpoB1). Under these conditions, mutants in ppoB2 (such as strain T105) produce PpoB1 as an apoenzyme that can be reconstituted to the active holoenzyme by the addition of cupric ions to cell extracts. To study PpoB2 functionality, a system was developed for genetic complementation in M. mediterranea. Using this approach, melanin synthesis was restored in strain T105 when a wild-type copy of ppoB2 was introduced. PpoB2 is a novel protein since it is believed to be the first to be described that contains several motifs similar to metal binding motifs present separately in other types of copper-related protein. At least three motifs, a His-rich N-terminal region, and the short CxxxC and MxxxMM sequences, are essential for the functionality of PpoB2, since site-directed mutagenesis of these motifs resulted in a non-functional protein. In addition, it was demonstrated that PpoB2 is a membrane copper transporter putatively participating in the delivery of this ion specifically to the tyrosinase of M. mediterranea and not to a second copper oxidase showing laccase activity that this micro-organism also expresses. PpoB2 has similarities with the COG5486 group encoding putative transmembrane metal binding proteins, and is believed to be the first protein in this group to be experimentally characterized. It may constitute the first example of a novel type of protein involved in copper trafficking in bacteria. (+info)
Hydrogen peroxide linked to lysine oxidase activity facilitates biofilm differentiation and dispersal in several gram-negative bacteria.