Protein CoAlation and antioxidant function of coenzyme A in prokaryotic cells.

In all living organisms, coenzyme A (CoA) is an essential cofactor with a unique design allowing it to function as an acyl group carrier and a carbonyl-activating group in diverse biochemical reactions. It is synthesized in a highly conserved process in prokaryotes and eukaryotes that requires pantothenic acid (vitamin B5), cysteine and ATP. CoA and its thioester derivatives are involved in major metabolic pathways, allosteric interactions and the regulation of gene expression. A novel unconventional function of CoA in redox regulation has been recently discovered in mammalian cells and termed protein CoAlation. Here, we report for the first time that protein CoAlation occurs at a background level in exponentially growing bacteria and is strongly induced in response to oxidizing agents and metabolic stress. Over 12% of Staphylococcus aureus gene products were shown to be CoAlated in response to diamide-induced stress. In vitro CoAlation of S. aureus glyceraldehyde-3-phosphate dehydrogenase was found to inhibit its enzymatic activity and to protect the catalytic cysteine 151 from overoxidation by hydrogen peroxide. These findings suggest that in exponentially growing bacteria, CoA functions to generate metabolically active thioesters, while it also has the potential to act as a low-molecular-weight antioxidant in response to oxidative and metabolic stress.

Physical activity interferes with the immunomodulatory effect of the antineoplastic drug NSC631570.

OBJECTIVE: The aim of the work was to evaluate the effect of moderate physical exercise on the response of circulating phagocytes to the antineoplastic drug NSC 631570. METHODS: Eight healthy adult men aged 23 ± 2 years were recruited to participate in the study; NSC 631570 was administered i.v. in a single therapeutic dose; blood samples were collected before and after the drug administration; the moderate physical exercise programme included 50 slow squats; total leukocyte, neutrophil and lymphocyte counts were determined using the haematological analyser; intracellular ROS generation and phagocytic activity of circulating monocytes and granulocytes were analysed by flow cytometry; PPAR-γ protein expression was evaluated by Western blot. RESULTS: introduction of NSC 631570 in an inpatient setting was associated with a decrease in phagocyte endocytic activity along with an increase in ROS generation. Drug injection in an outpatient setting was accompanied by a significant increase in monocyte and granulocyte phagocytosis along with a decrease in the daily mean of ROS generation as well as by a decrease in monocyte reactivity reserve after stimulation in vitro. PPAR-γ expression in circulating monocytes was significantly decreased after the drug administration in an inpatient setting and was slightly increased in active participants after the drug injection. CONCLUSION: NSC 631570 causes M1 (N1) shift of phagocytes after in vivo introduction. Moderate physical exercise exerts a negative effect on the immunomodulatory action of NSC 631570 by abrogating M1 (N1) shift of circulating phagocytes. One of the reasons for such an effect could be an increase in PPAR-γ expression by phagocytes.