Propanediol utilization genes (pdu) of Salmonella typhimurium: three genes for the propanediol dehydratase.
The propanediol utilization (pdu) operon of Salmonella typhimurium encodes proteins required for the catabolism of propanediol, including a coenzyme B12-dependent propanediol dehydratase. A clone that expresses propanediol dehydratase activity was isolated from a Salmonella genomic library. DNA sequence analysis showed that the clone included part of the pduF gene, the pduABCDE genes, and a long partial open reading frame (ORF1). The clone included 3.9 kbp of pdu DNA which had not been previously sequenced. Complementation and expression studies with subclones constructed via PCR showed that three genes (pduCDE) are necessary and sufficient for propanediol dehydratase activity. The function of ORF1 was not determined. Analyses showed that the S. typhimurium propanediol dehydratase was related to coenzyme B12-dependent glycerol dehydratases from Citrobacter freundii and Klebsiella pneumoniae. Unexpectedly, the S. typhimurium propanediol dehydratase was found to be 98% identical in amino acid sequence to the Klebsiella oxytoca propanediol dehydratase; this is a much higher identity than expected, given the relationship between these organisms. DNA sequence analyses also supported previous studies indicating that the pdu operon was inherited along with the adjacent cobalamin biosynthesis operon by a single horizontal gene transfer.
Bobik
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TA
Department of Microbiology and Cell Science, University of Florida, Gainesville 32611, USA. bobik@micro.ifas.ufl.edu
Xu
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Jeter
R M
RM
Otto
K E
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Roth
J R
JR
D003038:Cobamides; D022761:Gene Transfer, Horizontal; D005798:Genes, Bacterial; D005816:Genetic Complementation Test; D015698:Genomic Library; D006836:Hydro-Lyases / Q000235:genetics; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D009876:Operon; D011408:Propanediol Dehydratase / Q000096:biosynthesis / Q000235:genetics*; D019946:Propylene Glycol / Q000378:metabolism*; D012486:Salmonella typhimurium / Q000235:genetics*; D017422:Sequence Analysis, DNA; D017385:Sequence Homology; D013045:Species Specificity
D003038:Cobamides; D019946:Propylene Glycol; D006836:Hydro-Lyases; D011408:Propanediol Dehydratase; C020671:glycerol dehydratase; C000913:cobamamide