Conserving a volatile metabolite: a role for carboxysome-like organelles in Salmonella enterica.
Salmonellae can use ethanolamine (EA) as a sole source of carbon and nitrogen. This ability is encoded by an operon (eut) containing 17 genes, only 6 of which are required under standard conditions (37 degrees C; pH 7.0). Five of the extra genes (eutM, -N, -L, -K, and -G) become necessary under conditions that favor loss of the volatile intermediate, acetaldehyde, which escapes as a gas during growth on EA and is lost at a higher rate from these mutants. The eutM, -N, -L, and -K genes encode homologues of shell proteins of the carboxysome, an organelle shown (in other organisms) to concentrate CO(2). We propose that carboxysome-like organelles help bacteria conserve certain volatile metabolites-CO(2) or acetaldehyde-perhaps by providing a low-pH compartment. The EutG enzyme converts acetaldehyde to ethanol, which may improve carbon retention by forming acetals; alternatively, EutG may recycle NADH within the carboxysome.
Penrod
Joseph T
JT
Microbiology Section, Division of Biological Sciences, University of California-Davis, Davis, CA, USA.
Roth
John R
JR
D000079:Acetaldehyde / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology*; D000431:Ethanol / Q000378:metabolism; D019856:Ethanolamine / Q000378:metabolism; D017353:Gene Deletion; D008954:Models, Biological; D015388:Organelles / Q000235:genetics / Q000502:physiology*; D012486:Salmonella typhimurium / Q000235:genetics / Q000254:growth & development / Q000502:physiology* / Q000648:ultrastructure
D001426:Bacterial Proteins; D000431:Ethanol; D019856:Ethanolamine; D000079:Acetaldehyde