Friday, 16 March 2018

An unusual form of antibiotic resistance in pandemic cholera


Researchers have now shown that the enzyme that makes the El Tor family of V. cholerae resistant to those antibiotics has a different mechanism of action from any comparable proteins observed in bacteria so far. Understanding that mechanism better equips researchers to overcome the challenge it presents in a world with increasing antibiotic resistance.

Cationic antimicrobial peptides, or CAMPs, are naturally produced by bacteria and by animals' innate immune systems and are also synthesized for use as last-line drugs. Cholera strains achieve resistance to CAMPs by chemically disguising the bacterium's cell wall, preventing CAMPs from binding, disrupting the wall and killing the bacterium.

Researchers had previously had shown that a group of three proteins carried out this modification and elucidated the functions of two of the proteins. Scientists reported the role of the third protein -- the missing piece in understanding CAMP resistance -- in a new paper.

Lipid A modification is a defense mechanism observed in other bacteria, but detailed biochemical characterization of AlmG showed that the way this process occurred in cholera was unique.

See:

Jeremy C. Henderson, Carmen M. Herrera, M. Stephen Trent. AlmG, responsible for polymyxin resistance in pandemicVibrio cholerae, is a glycyltransferase distantly related to lipid A late acyltransferasesJournal of Biological Chemistry, 2017; 292 (51): 21205 DOI: 10.1074/jbc.RA117.000131

Posted by Dr. Tim Sandle

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