Potential involvement of N-terminal acetylation in the quantitative regulation of the epsilon subunit of chloroplast ATP synthase under drought stress.
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In plants, modulation of photosynthetic energy conversion in varying environments is often accompanied by adjustment of the abundance of photosynthetic components. In wild watermelon (Citrullus lanatus L.), proteome analysis revealed that the epsilon subunit of chloroplast ATP synthase occurs as two distinct isoforms with largely-different isoelectric points, although encoded by a single gene. Mass spectrometry (MS) analysis of the epsilon isoforms indicated that the structural difference between the epsilon isoforms lies in the presence or absence of an acetyl group at the N-terminus. The protein level of the non-acetylated epsilon isoform preferentially decreased in drought, whereas the abundance of the acetylated epsilon isoform was unchanged. Moreover, metalloprotease activity that decomposed the epsilon subunit was detected in a leaf extract from drought-stressed plants. Furthermore, in vitro assay suggested that the non-acetylated epsilon subunit was more susceptible to degradation by metalloaminopeptidase. We propose a model in which quantitative regulation of the epsilon subunit involves N-terminal acetylation and stress-induced proteases. (+info)
Citrullus colocynthis failed to combat against renal derangements, in spite of its strong antioxidant properties.
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Gentamicin is a potent antibiotic, effective against Gram negative bacteria. The most common adverse effect of gentamicin is nephrotoxicity. Present study was aimed to explore the protective potentials of Citrullus colocynthis against gentamicin induced nephrotoxicity due to its strong antioxidant properties. Toxic doses of gentamicin (80 mg/kg/day, i.m.) were administered alone and as co-therapy with the extract of C. colocynthis (25 mg/kg/day, p.o.). Physiological, biochemical and histological examinations were performed to compare the experimental and toxic groups (n = 6) with control group animals. Co-therapy of C. colocynthis with gentamicin protected changes in the body weight, blood urea nitrogen, creatinine clearance, proteins and lactate dehydrogenase excretions. However, a significant rise in serum creatinine and serum uric acid with fall in serum calcium and serum potassium was observed, which were significantly different from control group animals. Necrotic and ruptured tubules were also found abundantly. This study revealed that co-theapy of C. colocynthis with gentamicin for twenty one days, failed to protect renal injury associated by gentamicin in spite of its strong antioxidant properties. (+info)