Acidic pH promotes lipopolysaccharide modification and alters colonization in a bacteria–animal mutualism
Year: 2019
Type: article
Abstract: Environmental pH can be an important cue for symbiotic bacteria as they colonize their eukaryotic hosts. Using the model mutualism between the marine bacterium Vibrio fischeri and the Hawaiian bobtail squid, we characterized the bacterial transcriptional response to acidic pH experienced during the shift from planktonic to host-associated lifestyles. We found several genes involved in outer membrane structure were differentially expressed based on pH, indicating alterations in membrane physiology as V. fischeri initiates its symbiotic program. Exposure to host-like pH increased the resistance of V. fischeri to the cationic antimicrobial peptide polymixin B, which resembles antibacterial molecules that are produced by the squid to select V. fischeri from the ocean microbiota. Using a forward genetic screen, we identified a homolog of eptA, a predicted phosphoethanolamine transferase, as critical for antimicrobial defense. We used MALDI-MS to verify eptA as an ethanolamine transferase for the lipid-A portion of V. fischeri lipopolysaccharide. We then used a DNA pulldown approach to discover that eptA transcription is activated by the global regulator H-NS. Finally, we revealed that eptA promotes successful squid colonization by V. fischeri, supporting its potential role in initiation of this highly specific symbiosis.
Source: Molecular Microbiology
DOI: 10.1111/mmi.14365
Language: English
Subfield: Genetics
Domain: Life Sciences
Open Access status: bronze
Funders: National Science Foundation, National Institutes of Health, NIH Office of the Director, National Institute of General Medical Sciences, National Institute of Allergy and Infectious Diseases, National Institute of Diabetes and Digestive and Kidney Diseases, National Center for Research Resources, Division of Integrative Organismal Systems
Awards: Determination of outer membrane vesicle composition and effector activity in the Vibrio fischeri-Euprymna scolopes symbiosis, G406573444, G4331284377, G4620184477, National Biomedical NMR Resource at Madison, G5305468644, Vibrio virulence determinants in a benign colonization, Vibrio fischeri as a model of Bacterial Colonization, G5498018826, G5855963385, Vibrio colonization determinants in symbiosis, G7187779997, Chemistry-Biology Interface Training Program, G843635962, Microbes in Health and Disease, Vibrio fischeri as a Model for Bacterial Colonization, Vermont Biomedical Research Network-Vermont INBRE, Precision Medicine Center for Cystic Fibrosis
OpenAlex ID: W2969080413