Regulation of D-galacturonate metabolism in Caulobacter crescentus by HumR, a LacI-family transcriptional repressor

Sheikh, Aaesha I. and Caswell, Deborah and Dick, Cynthia and Gang, Spencer and Jarrell, Justin and Kohli, Ankita and Lieu, Amanda and Lumpe, Jared and Garrett, Meghan and Parker, Jennifer and Stephens, Craig (2013) Regulation of D-galacturonate metabolism in Caulobacter crescentus by HumR, a LacI-family transcriptional repressor. Advances in Bioscience and Biotechnology, 04 (10). pp. 63-74. ISSN 2156-8456

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Abstract

The oligotrophic freshwater bacterium Caulobacter crescentus encodes a cluster of genes (CC_1487 to CC_1495) shown here to be necessary for metabolism of D-galacturonate, the primary constituent of pectin, a major plant polymer. Sequence analysis suggests that these genes encode a version of the bacterial hexuronate isomerase pathway. A conserved 14 bp sequence motif is associated with promoter regions of three operons within this cluster, and is conserved in homologous gene clusters in related alpha-Proteobacteria. Embedded in the hexuronate gene cluster is a gene (CC_1489) encoding a member of the LacI family of bacterial transcription factors. This gene product, designated here as HumR (hexuronate metabolism regulator), represses expression of the uxaA and uxaC operon promoters by binding to the conserved operator sequence. Repression is relieved in the presence of galacturonate or, to a lesser extent, by glucuronate. Other genes potentially involved in pectin degradation and hexuronate transport are also under the control of HumR. Adoption of a LacI-type repressor to control hexuronate metabolism parallels the regulation of xylose, glucose, and maltose utilization in C. crescentus, but is distinct from the use of GntR-type repressors to control pectin and hexuronate utilization in gamma-Proteobacteria such as Escherichia coli.

Item Type: Article
Subjects: Science Global Plos > Biological Science
Depositing User: Unnamed user with email support@science.globalplos.com
Date Deposited: 18 Mar 2023 10:19
Last Modified: 26 Mar 2024 03:41
URI: http://ebooks.manu2sent.com/id/eprint/375

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