Characterization of htrB and msbB mutants of the light organ symbiont Vibrio fischeri.
Bacterial lipid A is an important mediator of bacterium-host interactions, and secondary acylations added by HtrB and MsbB can be critical for colonization and virulence in pathogenic infections. In contrast, Vibrio fischeri lipid A stimulates normal developmental processes in this bacterium's mutualistic host, Euprymna scolopes, although the importance of lipid A structure in this symbiosis is unknown. To further examine V. fischeri lipid A and its symbiotic function, we identified two paralogs of htrB (designated htrB1 and htrB2) and an msbB gene in V. fischeri ES114 and demonstrated that these genes encode lipid A secondary acyltransferases. htrB2 and msbB are found on the Vibrio "housekeeping" chromosome 1 and are conserved in other Vibrio species. Mutations in htrB2 and msbB did not impair symbiotic colonization but resulted in phenotypic alterations in culture, including reduced motility and increased luminescence. These mutations also affected sensitivity to sodium dodecyl sulfate, kanamycin, and polymyxin, consistent with changes in membrane permeability. Conversely, htrB1 is located on the smaller, more variable vibrio chromosome 2, and an htrB1 mutant was wild-type-like in culture but appeared attenuated in initiating the symbiosis and was outcompeted 2.7-fold during colonization when mixed with the parent. These data suggest that htrB2 and msbB play conserved general roles in vibrio biology, whereas htrB1 plays a more symbiosis-specific role in V. fischeri.
University of Georgia, Department of Microbiology, 1000 Cedar Street, Athens, GA 30602, USA.
Dawn M
DM
Adin
Nancy J
NJ
Phillips
Bradford W
BW
Gibson
Michael A
MA
Apicella
Edward G
EG
Ruby
Margaret J
MJ
McFall-Ngai
Daniel B
DB
Hall
Eric V
EV
Stabb
D000217:Acyltransferases / Q000235:genetics* / Q000378:metabolism; D048908:Aliivibrio fischeri / Q000201:enzymology / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D000825:Animal Structures / Q000382:microbiology*; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D002876:Chromosomes, Bacterial / Q000235:genetics; D049832:Decapodiformes / Q000033:anatomy & histology / Q000382:microbiology*; D008027:Light; D008050:Lipid A / Q000378:metabolism*; D009154:Mutation; D013559:Symbiosis
D001426:Bacterial Proteins; D008050:Lipid A; D000217:Acyltransferases