Figure 1
Ethanolamine utilization in Vibrio spp. a) Schematic diagram of ethanolamine utilization: Ethanolamine is transported into the cytoplasm by the action of transporter proteins EutH, eat and via passive diffusion. Ethanolamine is then broken down into ammonia and acetaldehyde by the EutBC complex. Ammonia is further utilized by the purine and amino-acid synthesis pathways. Acetaldehyde is converted into Acetyl-P and Acetyl-CoA by the action of EutD, EutE and EutG proteins. The microcompartment made up of the EutKLMNS structural proteins help sequester volatile metabolites like acetaldehyde and the enzymes required for ethanolamine utilization. The microcompartment and EutH proteins which are not present in V. alginolyticus are circled with dotted lines. Structural diagrams of homology models of the various enzymes are shown at their respective locations in the pathway. The EutB protein adopts a TIM barrel fold; the EutC protein adopts an anticodon-binding domain like fold while EutD, EutE and EutG adopt the Rossmann fold. b) Maximum likelihood evolutionary tree based on the EutB sequences: The branch color represents bootstrap support: green >80% and red <50%. The colored circle marks bacterial clades: burly wood, Alphaproteobacteria; chocolate, Betaproteobacteria; dark sea green, Gammaproteobacteria; corn flower blue, Deltaproteobacteria; cyan, Firmicutes; blue violet, Actinobacter; dark cyan, Acidobacter; dark olive green, Fusobacter; grey, Chlorophlexi; and dark salmon, Bacteroidetes. The ovals with shaded background mark the clades that contain Gammaproteobacteria. Abbreviations of organism names are as per the Additional file 2: Figure S1. c) Growth curve of Vibrio alginolyticus in minimal media containing ethanolamine: 25 ml minimal media was inoculated with a 1:100 dilution of an exponentially grown culture of Vibrio alginolyticus strain V105. The culture was grown at 30°C and growth at various time points was monitored spectrophotometrically by measuring OD600nm.