Spontaneous mutations affecting transcriptional regulation by protocatechuate in Acinetobacter

D’Argenio, David A.

doi:10.1016/s0378-1097(01)00247-6

Cited by 5 publications

(7 citation statements)

References 16 publications

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“…Indication for a physiological function of these external sequence repetitions comes from the observed growth phenotypes of two spontaneous mutant strains, one containing a C3T base substitution within the external sequence repetition and the second one with a deletion of the direct sequence repetition. The respective strains show a cold-enhanced block in protocatechuate catabolism (7,42). Thus both PcaU binding and gene expression are impaired when one of the external sequence repetitions is modified or deleted, and possibly pca gene expression is not inducible at all.…”

Section: Discussionmentioning

confidence: 99%

“…Both fragments contain three sequence repetitions; it has been suggested that these are recognized and bound by PcaU (17). A first indication that full transcriptional activation requires the presence of all three sequence repetitions comes from the recent identification of spontaneous mutations in the pcaU-pcaI intergenic region (7). Nothing is known about the way in which PcaU interacts with this unusual potential binding site and how communication with RNA polymerase is accomplished.…”

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confidence: 99%

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Differential DNA Binding of Transcriptional Regulator PcaU from Acinetobacter sp. Strain ADP1

et al. 2002

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Differential DNA Binding of Transcriptional Regulator PcaU from Acinetobacter sp. Strain ADP1

et al. 2002

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“…In one study, a quarter of the spontaneous mutations were deletions, and some of them extended into neighboring genes (18). The discovery that some of the deletions upstream of the pca structural genes eliminated the ability of strains to grow on the six-carbon dicarboxylic acid, adipic acid, provided the first evidence for linkage of adipate utilization genes and pca genes (10,11).…”

mentioning

confidence: 99%

Cloning and Genetic Characterization of dca Genes Required for β-Oxidation of Straight-Chain Dicarboxylic Acids in Acinetobacter sp. Strain ADP1

Parke

García

Ornston

2001

Appl Environ Microbiol

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A previous study of deletions in the protocatechuate (pca) region of the Acinetobacter sp. strain ADP1 chromosome revealed that genes required for utilization of the six-carbon dicarboxylic acid, adipic acid, are linked to the pca structural genes. To investigate the genes involved in adipate catabolism, a 33.8-kb SacI fragment, which corrects a deletion spanning this region, was cloned. In addition to containing known pca, qui, and pob genes (for protocatechuate, quinate, and 4-hydroxybenzoate dissimilation), clone pZR8000 contained 10 kb of DNA which was the subject of this investigation. A mutant strain of Escherichia coli DH5␣, strain EDP1, was isolated that was able to utilize protocatechuate and 4-hydroxybenzoate as growth substrates when EDP1 cells contained pZR8000. Sequence analysis of the new region of DNA on pZR8000 revealed open reading frames predicted to be involved in ␤-oxidation. Knockouts of three genes implicated in ␤-oxidation steps were introduced into the chromosome of Acinetobacter sp. strain ADP1. Each of the mutants was unable to grow with adipate. Because the mutants were affected in their ability to utilize additional saturated, straight-chain dicarboxylic acids, the newly discovered 10 kb of DNA was termed the dca (dicarboxylic acid) region. Mutant strains included one with a deletion in dcaA (encoding an acyl coenzyme A [acyl-CoA] dehydrogenase homolog), one with a deletion in dcaE (encoding an enoyl-CoA hydratase homolog), and one with a deletion in dcaH (encoding a hydroxyacyl-CoA dehydrogenase homolog). Data on the dca region should help us probe the functional significance and interrelationships of clustered genetic elements in this section of the Acinetobacter chromosome.

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“…PcaU may be involved in a regulon whose target genes have yet to be fully characterized. Sequence similarities between the PcaU and PobR regulators have led to speculation that these two regulators, like BenM and CatM, have overlapping or interconnected functions (9,21,39).…”

Section: Discussionmentioning

confidence: 99%

Transcriptional Cross-Regulation of the Catechol and Protocatechuate Branches of the β-Ketoadipate Pathway Contributes to Carbon Source-Dependent Expression of the Acinetobacter sp. Strain ADP1 pobA Gene

Brzostowicz

Reams

Clark

et al. 2003

Appl Environ Microbiol

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Transcriptional control of carbon source preferences by Acinetobacter sp. strain ADP1 was assessed with a pobA::lacZ fusion during growth on alternative substrates. The pobA-encoded enzyme catalyzes the first step in the degradation of 4-hydroxybenzoate, a compound consumed rapidly as a sole carbon source. If additional aromatic carbon sources are available, 4-hydroxybenzoate consumption is inhibited by unknown mechanisms. As reported here, during growth on aromatic substrates, pobA was not expressed despite the presence of 4-hydroxybenzoate, an inducer that normally causes the PobR regulator to activate pobA transcription. Growth on organic acids such as succinate, fumarate, and acetate allowed higher levels of pobA expression. In each case, pobA expression increased at the end of the exponential growth phase. Complex transcriptional regulation controlled 4-hydroxybenzoate catabolism in multisubstrate environments. Additional studies focused on the wild-type preference for benzoate consumption prior to 4-hydroxybenzoate consumption. These compounds are degraded via the catechol and protocatechuate branches of the ␤-ketoadipate pathway, respectively. Here, mutants were characterized that degraded benzoate and 4-hydroxybenzoate concurrently. These mutants lacked the BenM and CatM transcriptional regulators that normally activate genes for benzoate catabolism. A model is presented in which BenM and CatM prevent pobA expression indirectly during growth on benzoate. These regulators may affect pobA expression by lowering the PcaK-mediated uptake of 4-hydroxybenzoate. Consistent with this model, BenM and CatM bound in vitro to an operator-promoter fragment controlling the expression of several pca genes, including pcaK. These studies provide the first direct evidence of transcriptional cross-regulation between the distinct but analogous branches of the ␤-ketoadipate pathway.

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Spontaneous mutations affecting transcriptional regulation by protocatechuate in Acinetobacter

Cited by 5 publications

References 16 publications

Differential DNA Binding of Transcriptional Regulator PcaU from Acinetobacter sp. Strain ADP1

Differential DNA Binding of Transcriptional Regulator PcaU from Acinetobacter sp. Strain ADP1

Cloning and Genetic Characterization of dca Genes Required for β-Oxidation of Straight-Chain Dicarboxylic Acids in Acinetobacter sp. Strain ADP1

Transcriptional Cross-Regulation of the Catechol and Protocatechuate Branches of the β-Ketoadipate Pathway Contributes to Carbon Source-Dependent Expression of the Acinetobacter sp. Strain ADP1 pobA Gene

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