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

Author(s)

dos Santos, Naara M. ; Picinato, Beatriz A. ; Santos, Lucas S. ; de Araujo, Hugo L. ; Balan, Andrea ; Koide, Tie ; Marques, Marilis V.

• Document type: Journal article
• Source: FRONTIERS IN MICROBIOLOGY; v. 15, p. 18-pg., 2024-09-30.

Abstract

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 Delta iscR 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. (AU)

• FAPESP's process: 21/10577-0 - Biology of Bacteria and Bacteriophages Research Center
• Grantee: Shaker Chuck Farah
• Support Opportunities: Research Grants - Research, Innovation and Dissemination Centers - RIDC
• FAPESP's process: 22/00308-4 - Identification and comparison of circular RNAs in archaeal transcriptome data
• Grantee: Beatriz Adas Picinato
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)
• FAPESP's process: 20/10171-0 - Mechanistic of the phosphate-uptake and regulation: the close relationship between an ATP-binding cassette transporter and a two-component system
• Grantee: Lucas Souza dos Santos
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)
• FAPESP's process: 22/06360-8 - Characterization of new regulatory circuits for gene expression in Alphaproteobacteria
• Grantee: Marilis Do Valle Marques
• Support Opportunities: Regular Research Grants
• FAPESP's process: 18/17309-8 - Study of the role of the DEAD-box RNA helicase RhlB in the RNA stability and gene expression in Caulobacter crescentus
• Grantee: Hugo Libonati de Araújo
• Support Opportunities: Scholarships in Brazil - Doctorate