The LysR-type PcaQ protein regulates expression of a protocatechuate-inducible ABC-type transport system in Sinorhizobium meliloti

MacLean, Allyson M., Haerty, Wilfried ORCID: https://orcid.org/0000-0003-0111-191X, Golding, G. Brian and Finan, Turlough M. (2011) The LysR-type PcaQ protein regulates expression of a protocatechuate-inducible ABC-type transport system in Sinorhizobium meliloti. Microbiology, 157 (9). pp. 2522-2533. ISSN 1350-0872

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Abstract

The LysR protein PcaQ regulates the expression of genes encoding products relevant to the degradation of the aromatic acid protocatechuate (3,4-dihydroxybenzoate), and we have previously defined a PcaQ DNA-binding site located upstream of the target pcaDCHGB operon in Sinorhizobium meliloti. In this work, we show that PcaQ also regulates the expression of the S. meliloti smb20568-smb20787-smb20786-smb20785-smb20784 gene cluster, which is predicted to encode an ABC transport system. ABC transport systems have not been shown before to transport protocatechuate, and we have designated this gene cluster pcaMNVWX. The transcriptional start site of pcaM was mapped, and the predicted PcaQ DNA-binding site was located at "73 to "58 relative to this site. Results from electrophoretic mobility shift assays with purified PcaQ and from expression assays indicated that PcaQ activates expression of the transport system in the presence of protocatechuate. To investigate this transport system further, we generated a pcaM deletion mutant (predicted to encode the substrate-binding protein) and introduced a polar insertion mutation into pcaN, a gene that is predicted to encode a permease. These mutants grew poorly on protocatechuate, presumably because they fail to transport protocatechuate. Genome analyses revealed PcaQ-like DNA-binding sites encoded upstream of ABC transport systems in other members of the a-proteobacteria, and thus it appears likely that these systems are involved in the uptake of protocatechuate.

Item Type: Article
Uncontrolled Keywords: microbiology ,/dk/atira/pure/subjectarea/asjc/2400/2404
Faculty \ School: Faculty of Science > School of Biological Sciences
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Depositing User: LivePure Connector
Date Deposited: 15 Sep 2022 14:31
Last Modified: 26 Sep 2022 13:31
URI: https://ueaeprints.uea.ac.uk/id/eprint/88335
DOI: 10.1099/mic.0.050542-0

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