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ORIGINAL RESEARCH article

Front. Microbiol.
Sec. Microbial Physiology and Metabolism
Volume 15 - 2024 | doi: 10.3389/fmicb.2024.1463854

Mapping the IscR regulon sheds light on the regulation of iron homeostasis in Caulobacter

Provisionally accepted
Naara M. Santos Naara M. Santos 1Beatriz A. Picinato Beatriz A. Picinato 2Lucas S. Santos Lucas S. Santos 1Hugo L. de Araújo Hugo L. de Araújo 1Andrea Balan Andrea Balan 1Tie Koide Tie Koide 2Marilis V. Marques Marilis V. Marques 1*
  • 1 University of São Paulo, São Paulo, Brazil
  • 2 Universidade de São Paulo, Ribeirão Preto, Brazil

The final, formatted version of the article will be published soon.

    The role of the iron-sulfur [Fe-S] cluster transcriptional regulator IscR in maintaining [Fe-S] homeostasis in bacteria is still poorly characterized in many groups. Caulobacter crescentus and other Alphaproteobacteria have a single operon encoding [Fe-S] cluster biosynthesis enzymes. We showed that the expression of this operon increases in iron starvation, but not in oxidative stress, and is controlled mainly by IscR. Transcriptome analysis comparing an iscR null mutant strain with the wild-type (wt) strain identified 94 differentially expressed genes (DEGs), with 47 upregulated and 47 downregulated genes in the DiscR mutant. We determined the IscR binding sites in conditions of sufficient or scarce iron by Chromatin Immunoprecipitation followed by DNA sequencing (ChIP-seq), identifying two distinct putative DNA binding motifs. The estimated IscR regulon comprises 302 genes, and direct binding to several regulatory regions was shown by Electrophoresis Mobility Shift Assay (EMSA). The results showed that the IscR and Fur regulons partially overlap and that IscR represses the expression of the respiration regulator FixK, fine-tuning gene regulation in response to iron and redox balance.

    Keywords: iron-sulfur cluster, IscR, Fur, gene regulation, Caulobacter crescentus

    Received: 12 Jul 2024; Accepted: 28 Aug 2024.

    Copyright: © 2024 Santos, Picinato, Santos, de Araújo, Balan, Koide and Marques. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence: Marilis V. Marques, University of São Paulo, São Paulo, Brazil

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