Abstract
Gram-negative bacteria remodel their surfaces to interact with the environment, particularly to protect pathogens from immune surveillance and host defenses. The enzyme AlmG is known to be involved in remodeling the Vibrio cholerae surface, but its specific role was not clear. A new study characterizes AlmG at the molecular level, showing it defies phylogenetic expectations to add amino acids to lipopolysaccharide (LPS). This LPS modification plays a pivotal role in V. cholerae resistance to antimicrobial peptides, weapons of the innate immune system against infections.
Highlights
A defining feature of Gram-negative bacteria is the presence of an outer membrane, which is an asymmetrical bilayer with glycerophospholipids on the cytoplasmic face and LPS2 anchored to the outer face
Until recently, there was a major gap in our understanding of V. cholerae LPS and its contribution to virulence, even though resistance to polymyxin B has been used as diagnostic test to differentiate the two V. cholerae O1 biotypes, El Tor and Classical
To characterize the enzymatic activity of AlmG, the authors followed an elegant synthetic biology approach combining the power of bacterial engineering and biochemistry methods and exploiting E. coli as a workhorse
Summary
A defining feature of Gram-negative bacteria is the presence of an outer membrane, which is an asymmetrical bilayer with glycerophospholipids on the cytoplasmic face and LPS2 anchored to the outer face. Stephen Trent’s team uncovered that V. cholerae O1 El Tor pandemic strains synthesize novel mono- or diglycine-modified lipid A species (Fig. 1) that confer resistance to polymyxin B and identified the proteins AlmE, AlmF, and AlmG as required for this modification [5]. They later showed that Classical V. cholerae strains lack a functional AlmEGF due to a mutation in AlmF, providing further evidence for this mechanism and explaining the mystery of why pandemic Classical strains are polymyxin B–susceptible [6].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
