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Author(s): Santos, JA
Alonso-García, N
Macedo-Ribeiro, S
Pereira, PJ
Title: The unique regulation of iron-sulfur cluster biogenesis in a Gram-positive bacterium
Publisher: National Academy of Sciences
Issue Date: 2014
Abstract: Iron-sulfur clusters function as cofactors of a wide range of proteins, with diverse molecular roles in both prokaryotic and eukaryotic cells. Dedicated machineries assemble the clusters and deliver them to the final acceptor molecules in a tightly regulated process. In the prototypical Gram-negative bacterium Escherichia coli, the two existing iron-sulfur cluster assembly systems, iron-sulfur cluster (ISC) and sulfur assimilation (SUF) pathways, are closely interconnected. The ISC pathway regulator, IscR, is a transcription factor of the helix-turn-helix type that can coordinate a [2Fe-2S] cluster. Redox conditions and iron or sulfur availability modulate the ligation status of the labile IscR cluster, which in turn determines a switch in DNA sequence specificity of the regulator: cluster-containing IscR can bind to a family of gene promoters (type-1) whereas the clusterless form recognizes only a second group of sequences (type-2). However, iron-sulfur cluster biogenesis in Gram-positive bacteria is not so well characterized, and most organisms of this group display only one of the iron-sulfur cluster assembly systems. A notable exception is the unique Gram-positive dissimilatory metal reducing bacterium Thermincola potens, where genes from both systems could be identified, albeit with a diverging organization from that of Gram-negative bacteria. We demonstrated that one of these genes encodes a functional IscR homolog and is likely involved in the regulation of iron-sulfur cluster biogenesis in T. potens. Structural and biochemical characterization of T. potens and E. coli IscR revealed a strikingly similar architecture and unveiled an unforeseen conservation of the unique mechanism of sequence discrimination characteristic of this distinctive group of transcription regulators.
Subject: Crystallography, X-Ray
DNA Bacterial/metabolism
DNA-Binding Proteins/genetics
DNA-Binding Proteins/metabolism
Escherichia coli K12/genetics
Escherichia coli K12/metabolism
Escherichia coli Proteins/genetics
Escherichia coli Proteins/metabolism
Gene Expression Regulation, Bacterial
Gram-Positive Bacteria/genetics
Gram-Positive Bacteria/metabolism
Helix-Turn-Helix Motifs
Iron-Sulfur Proteins/genetics
Iron-Sulfur Proteins/metabolism
Point Mutation
Promoter Regions Genetic
Protein Structure Tertiary
Transcription Factors/genetics
Transcription Factors/metabolism
Source: Proceedings of the National Academy of Sciences of the United States of America, vol. 111(22), p. E2251-60
Related Information: info:eu-repo/grantAgreement/FCT/COMPETE/127722/PT
Document Type: Artigo em Revista Científica Internacional
Rights: openAccess
Appears in Collections:I3S - Artigo em Revista Científica Internacional

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