SufR coordinates two [4Fe-4S]2+,1+ clusters and functions as a transcriptional repressor of the sufBCDS operon and an autoregulator of sufR in cyanobacteria

Gaozhong Shen, Ramakrishnan Balasubramanian, Tao Wang, Yingxian Wu, Lee M. Hoffart, Carsten Krebs, Donald A. Bryant, John H. Golbeck

Research output: Contribution to journalArticle

49 Citations (Scopus)

Abstract

The sufR gene encodes a protein that functions as a transcriptional repressor of the suf regulon in cyanobacteria. It is predicted to contain an N-terminal helix loop helix DNA binding motif and a C-terminal Fe/S binding domain. Through immunoblotting assays of cell extracts, the sufR product in Synechocystis sp. PCC 6803 was shown to have a mass of ∼25 kDa. This indicates that the second ATG in the open reading frame is the correct start codon and that sufR encodes a protein of 216 amino acids (SufR216) rather than the originally predicted 240 amino acids. Recombinant SufR 216 harbored [4Fe-4S]2+,1+ clusters, which were present in a mixture of S = 1/2 and 3/2 ground spin states, and the holoprotein was a homodimer, containing 3.7 of non-heme irons and 3.5 labile sulfides per monomer. Thus, two [4Fe-4S]2+,1+ clusters are coordinated by each SufR 216 homodimer. SufR216 bound to two DNA sequences in the regulatory region between the divergently transcribed sufR gene and the sufBCDS operon, and its binding affinity depended on the presence and redox state of the [4Fe-4S]2+,1+ clusters. A high affinity binding site, which controls sufBCDS expression, and a low affinity binding site, which controls sufR expression, were identified. The SufR binding sites, which are separated by 26 base pairs, each contain a perfect inverted repeat, CAAC-N6-GTTG, and are highly conserved in cyanobacteria. The Fe/S protein SufR thus functions both as a transcriptional repressor of the sufBCDS operon and as an autoregulator of sufR.

Original languageEnglish (US)
Pages (from-to)31909-31919
Number of pages11
JournalJournal of Biological Chemistry
Volume282
Issue number44
DOIs
StatePublished - Nov 2 2007

Fingerprint

Cyanobacteria
Operon
Binding Sites
Genes
Synechocystis
Amino Acids
Regulon
Nucleotide Motifs
Initiator Codon
Nucleic Acid Regulatory Sequences
DNA sequences
Protein S
Sulfides
Cell Extracts
Immunoblotting
Base Pairing
Open Reading Frames
Oxidation-Reduction
Assays
Proteins

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Cite this

@article{47b95e8c95f3470f8cbce173704b9f6a,
title = "SufR coordinates two [4Fe-4S]2+,1+ clusters and functions as a transcriptional repressor of the sufBCDS operon and an autoregulator of sufR in cyanobacteria",
abstract = "The sufR gene encodes a protein that functions as a transcriptional repressor of the suf regulon in cyanobacteria. It is predicted to contain an N-terminal helix loop helix DNA binding motif and a C-terminal Fe/S binding domain. Through immunoblotting assays of cell extracts, the sufR product in Synechocystis sp. PCC 6803 was shown to have a mass of ∼25 kDa. This indicates that the second ATG in the open reading frame is the correct start codon and that sufR encodes a protein of 216 amino acids (SufR216) rather than the originally predicted 240 amino acids. Recombinant SufR 216 harbored [4Fe-4S]2+,1+ clusters, which were present in a mixture of S = 1/2 and 3/2 ground spin states, and the holoprotein was a homodimer, containing 3.7 of non-heme irons and 3.5 labile sulfides per monomer. Thus, two [4Fe-4S]2+,1+ clusters are coordinated by each SufR 216 homodimer. SufR216 bound to two DNA sequences in the regulatory region between the divergently transcribed sufR gene and the sufBCDS operon, and its binding affinity depended on the presence and redox state of the [4Fe-4S]2+,1+ clusters. A high affinity binding site, which controls sufBCDS expression, and a low affinity binding site, which controls sufR expression, were identified. The SufR binding sites, which are separated by 26 base pairs, each contain a perfect inverted repeat, CAAC-N6-GTTG, and are highly conserved in cyanobacteria. The Fe/S protein SufR thus functions both as a transcriptional repressor of the sufBCDS operon and as an autoregulator of sufR.",
author = "Gaozhong Shen and Ramakrishnan Balasubramanian and Tao Wang and Yingxian Wu and Hoffart, {Lee M.} and Carsten Krebs and Bryant, {Donald A.} and Golbeck, {John H.}",
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SufR coordinates two [4Fe-4S]2+,1+ clusters and functions as a transcriptional repressor of the sufBCDS operon and an autoregulator of sufR in cyanobacteria. / Shen, Gaozhong; Balasubramanian, Ramakrishnan; Wang, Tao; Wu, Yingxian; Hoffart, Lee M.; Krebs, Carsten; Bryant, Donald A.; Golbeck, John H.

In: Journal of Biological Chemistry, Vol. 282, No. 44, 02.11.2007, p. 31909-31919.

Research output: Contribution to journalArticle

TY - JOUR

T1 - SufR coordinates two [4Fe-4S]2+,1+ clusters and functions as a transcriptional repressor of the sufBCDS operon and an autoregulator of sufR in cyanobacteria

AU - Shen, Gaozhong

AU - Balasubramanian, Ramakrishnan

AU - Wang, Tao

AU - Wu, Yingxian

AU - Hoffart, Lee M.

AU - Krebs, Carsten

AU - Bryant, Donald A.

AU - Golbeck, John H.

PY - 2007/11/2

Y1 - 2007/11/2

N2 - The sufR gene encodes a protein that functions as a transcriptional repressor of the suf regulon in cyanobacteria. It is predicted to contain an N-terminal helix loop helix DNA binding motif and a C-terminal Fe/S binding domain. Through immunoblotting assays of cell extracts, the sufR product in Synechocystis sp. PCC 6803 was shown to have a mass of ∼25 kDa. This indicates that the second ATG in the open reading frame is the correct start codon and that sufR encodes a protein of 216 amino acids (SufR216) rather than the originally predicted 240 amino acids. Recombinant SufR 216 harbored [4Fe-4S]2+,1+ clusters, which were present in a mixture of S = 1/2 and 3/2 ground spin states, and the holoprotein was a homodimer, containing 3.7 of non-heme irons and 3.5 labile sulfides per monomer. Thus, two [4Fe-4S]2+,1+ clusters are coordinated by each SufR 216 homodimer. SufR216 bound to two DNA sequences in the regulatory region between the divergently transcribed sufR gene and the sufBCDS operon, and its binding affinity depended on the presence and redox state of the [4Fe-4S]2+,1+ clusters. A high affinity binding site, which controls sufBCDS expression, and a low affinity binding site, which controls sufR expression, were identified. The SufR binding sites, which are separated by 26 base pairs, each contain a perfect inverted repeat, CAAC-N6-GTTG, and are highly conserved in cyanobacteria. The Fe/S protein SufR thus functions both as a transcriptional repressor of the sufBCDS operon and as an autoregulator of sufR.

AB - The sufR gene encodes a protein that functions as a transcriptional repressor of the suf regulon in cyanobacteria. It is predicted to contain an N-terminal helix loop helix DNA binding motif and a C-terminal Fe/S binding domain. Through immunoblotting assays of cell extracts, the sufR product in Synechocystis sp. PCC 6803 was shown to have a mass of ∼25 kDa. This indicates that the second ATG in the open reading frame is the correct start codon and that sufR encodes a protein of 216 amino acids (SufR216) rather than the originally predicted 240 amino acids. Recombinant SufR 216 harbored [4Fe-4S]2+,1+ clusters, which were present in a mixture of S = 1/2 and 3/2 ground spin states, and the holoprotein was a homodimer, containing 3.7 of non-heme irons and 3.5 labile sulfides per monomer. Thus, two [4Fe-4S]2+,1+ clusters are coordinated by each SufR 216 homodimer. SufR216 bound to two DNA sequences in the regulatory region between the divergently transcribed sufR gene and the sufBCDS operon, and its binding affinity depended on the presence and redox state of the [4Fe-4S]2+,1+ clusters. A high affinity binding site, which controls sufBCDS expression, and a low affinity binding site, which controls sufR expression, were identified. The SufR binding sites, which are separated by 26 base pairs, each contain a perfect inverted repeat, CAAC-N6-GTTG, and are highly conserved in cyanobacteria. The Fe/S protein SufR thus functions both as a transcriptional repressor of the sufBCDS operon and as an autoregulator of sufR.

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