Immunity system complexity: how E coli fights our system (Introduction)

by David Turell , Wednesday, August 10, 2022, 22:45 (624 days ago) @ David Turell

Chemical counterattack:

https://phys.org/news/2022-08-bacteria-defuse-hypothiocyanite-antimicrobial-weapon.html

"How do a wide variety of bacteria—both pathogenic and commensal—survive antimicrobials released by the mammalian innate immune system?

"The answer for one of the antimicrobials—hypothiocyanite/hypothiocyanous acid, or OSCN– and HOSCN—has been reported by Michael Gray, Ph.D., and colleagues through discovery of a novel role for an enzyme in E. coli. This previously unknown activity is also exhibited by homologous enzymes found in pathogenic Streptococcus and Staphylococcus bacteria and several commensal gut microbes.

"'During inflammation, the human immune system releases a variety of reactive and damaging antimicrobials meant to fight off invading pathogens," said Gray, an assistant professor in the University of Alabama at Birmingham Department of Microbiology. "Understanding how bacteria can evade these powerful oxidants, including the hypohalous acids like HOSCN, is crucial to human health.

"'By identifying the function of the enzyme RclA in the model organism E. coli—which notably is able to compete with commensal organisms and thrive in an inflamed gut—we have laid the foundation for understanding bacterial survival and the relationship to the human immune system in ways that were previously not understood," Gray said.

***

"Reporting in the journal Proceedings of the National Academy of Sciences, researchers led by Gray and Frederick Stull, assistant professor of chemistry at Western Michigan University, Kalamazoo, explain that the E. coli flavoprotein RclA reduces HOSCN to harmless thiocyanate with near-perfect catalytic efficiency, and this extremely fast activity strongly protects E. coli against HOSCN toxicity. HOSCN thus appears to be the physiologically relevant substrate for RclA, Gray says, rather than its previously described ability to modestly resist reactive chlorine."

Comment: it is as constant battle with each organism using highly complex organic molecules. The question ID always asks is how did these organisms find the right molecules hunting by chance through the millions of possible helpful ones"?