Genetic characterization of the pdu operon: use of 1,2-propanediol in Salmonella typhimurium.
Salmonella typhimurium is able to catabolize 1,2-propanediol for use as the sole carbon and energy source; the first enzyme of this pathway requires the cofactor adenosyl cobalamin (Ado-B12). Surprisingly, Salmonella can use propanediol as the sole carbon source only in the presence of oxygen but can synthesize Ado-B12 only anaerobically. To understand this situation, we have studied the pdu operon, which encodes proteins for propanediol degradation. A set of pdu mutants defective in aerobic degradation of propanediol (with exogenous vitamin B12) defines four distinct complementation groups. Mutations in two of these groups (pduC and pduD) eliminate propanediol dehydratase activity. Based on mutant phenotypes, a third complementation group (pduG) appears to encode a cobalamin adenosyl transferase activity. No function has been assigned to the pduJ complementation group. Propionaldehyde dehydrogenase activity is eliminated by mutations in any of the four identified complementation groups, suggesting that this activity may require a complex of proteins encoded by the operon. None of the mutations analyzed affects either of the first two genes of the operon (pduA and pduB), which were identified by DNA sequence analysis. Available data suggest that the pdu operon includes enough DNA for about 15 genes and that the four genetically identified genes are the only ones required for aerobic use of propanediol.
Walter
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D
Department of Biology, University of Utah, Salt Lake City 84112, USA.
Ailion
M
M
Roth
J
J
D000241:Adenosine / Q000378:metabolism; D000332:Aerobiosis; D000447:Aldehydes / Q000378:metabolism; D019883:Alkyl and Aryl Transferases; D000693:Anaerobiosis; D001426:Bacterial Proteins / Q000235:genetics; D002874:Chromosome Mapping; D004251:DNA Transposable Elements; D004268:DNA-Binding Proteins / Q000235:genetics; D005144:F Factor; D005816:Genetic Complementation Test; D016254:Mutagenesis, Insertional; D009876:Operon; D010088:Oxidoreductases / Q000235:genetics; D017354:Point Mutation; D011408:Propanediol Dehydratase / Q000235:genetics; D019946:Propylene Glycol; D011409:Propylene Glycols / Q000378:metabolism*; D012486:Salmonella typhimurium / Q000235:genetics* / Q000378:metabolism; D017384:Sequence Deletion; D015534:Trans-Activators; D014166:Transferases / Q000235:genetics; D014805:Vitamin B 12 / Q000378:metabolism
D000447:Aldehydes; D001426:Bacterial Proteins; D004251:DNA Transposable Elements; D004268:DNA-Binding Proteins; C084166:PocR protein, Salmonella; D011409:Propylene Glycols; D015534:Trans-Activators; D019946:Propylene Glycol; C005556:propionaldehyde; D010088:Oxidoreductases; D014166:Transferases; D019883:Alkyl and Aryl Transferases; C019920:cob(I)alamin adenosyltransferase; D011408:Propanediol Dehydratase; D000241:Adenosine; D014805:Vitamin B 12