HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Harrison, F. H. Articles by Harwood, C. S. Search for Related Content PubMed PubMed Citation Articles by Harrison, F. H. Articles by Harwood, C. S. Agricola Articles by Harrison, F. H. Articles by Harwood, C. S.

The pimFABCDE operon from Rhodopseudomonas palustris mediates dicarboxylic acid degradation and participates in anaerobic benzoate degradation

Caroline S. Harwood

Department of Microbiology, The University of Iowa, 3-450 BSB, Iowa City, IA 52242, USA

Correspondence
Caroline S. Harwood
csh5{at}u.washington.edu

Bacteria in anoxic environments typically convert aromatic compounds derived from pollutants or green plants to benzoyl-CoA, and then to the C₇ dicarboxylic acid derivative 3-hydroxypimelyl-CoA. Inspection of the recently completed genome sequence of the purple nonsulfur phototroph Rhodopseudomonas palustris revealed one predicted cluster of genes for the -oxidation of dicarboxylic acids. These genes, annotated as pimFABCDE, are predicted to encode acyl-CoA ligase, enoyl-CoA hydratase, acyl-CoA dehydrogenase and acyl-CoA transferase enzymes, which should allow the conversion of odd-chain dicarboxylic acids to glutaryl-CoA, and even-chain dicarboxylic acids to succinyl-CoA. A mutant strain that was deleted in the pim gene cluster grew at about half the rate of the wild-type parent when benzoate or pimelate was supplied as the sole carbon source. The mutant grew five times more slowly than the wild-type on the C₁₄ dicarboxylic acid tetradecanedioate. The mutant was unimpaired in growth on the C₈-fatty acid caprylate. The acyl-CoA ligase predicted to be encoded by the pimA gene was purified, and found to be active with C_7–C₁₄ dicarboxylic and fatty acids. The expression of a pimA–lacZ chromosomal gene fusion increased twofold when cells were grown in the presence of straight-chain C_7–C₁₄ dicarboxylic and fatty acids. These results suggest that the -oxidation enzymes encoded by the pim gene cluster are active with medium-chain-length dicarboxylic acids, including pimelate. However, the finding that the pim operon deletion mutant is still able to grow on dicarboxylic acids, albeit at a slower rate, indicates that R. palustris has additional genes that can also specify the degradation of these compounds.

Present address: Department of Microbiology, University of Washington, Box 357242, Seattle, WA 98195-7242, USA.

This article has been cited by other articles:

				C. M. Peres and C. S. Harwood BadM Is a Transcriptional Repressor and One of Three Regulators That Control Benzoyl Coenzyme A Reductase Gene Expression in Rhodopseudomonas palustris J. Bacteriol., December 15, 2006; 188(24): 8662 - 8665. [Abstract] [Full Text] [PDF]

				Y. Oda, S. K. Samanta, F. E. Rey, L. Wu, X. Liu, T. Yan, J. Zhou, and C. S. Harwood Functional Genomic Analysis of Three Nitrogenase Isozymes in the Photosynthetic Bacterium Rhodopseudomonas palustris J. Bacteriol., November 15, 2005; 187(22): 7784 - 7794. [Abstract] [Full Text] [PDF]