Functional replacement of the FabA and FabB proteins of Escherichia coli fatty acid synthesis by Enterococcus faecalis FabZ and FabF homologues.
The anaerobic unsaturated fatty acid synthetic pathway of Escherichia coli requires two specialized proteins, FabA and FabB. However, the fabA and fabB genes are found only in the Gram-negative alpha- and gamma-proteobacteria, and thus other anaerobic bacteria must synthesize these acids using different enzymes. We report that the Gram-positive bacterium Enterococcus faecalis encodes a protein, annotated as FabZ1, that functionally replaces the E. coli FabA protein, although the sequence of this protein aligns much more closely with E. coli FabZ, a protein that plays no specific role in unsaturated fatty acid synthesis. Therefore E. faecalis FabZ1 is a bifunctional dehydratase/isomerase, an enzyme activity heretofore confined to a group of Gram-negative bacteria. The FabZ2 protein is unable to replace the function of E. coli FabZ, although FabZ2, a second E. faecalis FabZ homologue, has this ability. Moreover, an E. faecalis FabF homologue (FabF1) was found to replace the function of E. coli FabB, whereas a second FabF homologue was inactive. From these data it is clear that bacterial fatty acid biosynthetic pathways cannot be deduced solely by sequence comparisons.
Wang
Haihong
H
Department of Microbiology, University of Illinois, 601 S. Goodwin Avenue, Urbana, IL 61801, USA.
Cronan
John E
JE
D015099:3-Oxoacyl-(Acyl-Carrier-Protein) Synthase / Q000235:genetics / Q000502:physiology*; D000213:Acyl Carrier Protein / Q000737:chemistry; D001089:Arabinose / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics* / Q000502:physiology*; D002474:Cell-Free System; D004247:DNA / Q000378:metabolism; D013293:Enterococcus faecalis / Q000378:metabolism*; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins; D054889:Fatty Acid Synthase, Type II; D005227:Fatty Acids / Q000096:biosynthesis* / Q000737:chemistry*; D005816:Genetic Complementation Test; D006836:Hydro-Lyases / Q000235:genetics / Q000502:physiology*; D009097:Multienzyme Complexes / Q000235:genetics*; D009154:Mutation; D010743:Phospholipids / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism
D000213:Acyl Carrier Protein; D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; C490371:FabZ protein, Enterococcus faecalis; D005227:Fatty Acids; D009097:Multienzyme Complexes; D010743:Phospholipids; D004247:DNA; D001089:Arabinose; D015099:3-Oxoacyl-(Acyl-Carrier-Protein) Synthase; C490369:FabB protein, E coli; C490370:FabF protein, Enterococcus faecalis; D006836:Hydro-Lyases; C047118:3-hydroxyacyl-(acyl-carrier-protein) dehydratase; D054889:Fatty Acid Synthase, Type II