HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

J. Biol. Chem., Vol. 282, Issue 44, 31909-31919, November 2, 2007

This Article Full Text Full Text (PDF) All Versions of this Article: 282/44/31909    most recent M705554200v1 Submit a Letter to Editor Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Shen, G. Articles by Golbeck, J. H. Search for Related Content PubMed PubMed Citation Articles by Shen, G. Articles by Golbeck, J. H. Social Bookmarking                      What's this?

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, and John H. Golbeck¹

From the Departments of Biochemistry and Molecular Biology and Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802

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 harbored [4Fe-4S]^{2+, 1+} ₂₁₆ 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 SufR₂₁₆ 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.

Received for publication, July 6, 2007 , and in revised form, September 5, 2007.

^* This work was supported by United States Department of Agriculture contract 2005-35318-15284 (to J. H. G. and D. A. B.), National Science Foundation Grant MCB-0077586 (to D. A. B. and J. H. G.), and "Center for the Study of Biometals in Health and Disease" Grant 417-12HY TSF (to C. K.). This project was also funded, in part, under a grant with the Pennsylvania Department of Health using Tobacco Settlement Funds. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement"in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

¹ To whom correspondence should be addressed: 310S Frear Bldg., The Pennsylvania State University, University Park, PA 16802. Tel.: 814-865-1163; Fax: 814-863-7024; E-mail: jhg5{at}psu.edu.

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				Z. Jin, M. Heinnickel, C. Krebs, G. Shen, J. H. Golbeck, and D. A. Bryant Biogenesis of Iron-Sulfur Clusters in Photosystem I: HOLO-NfuA FROM THE CYANOBACTERIUM SYNECHOCOCCUS SP. PCC 7002 RAPIDLY AND EFFICIENTLY TRANSFERS [4Fe-4S] CLUSTERS TO APO-PsaC IN VITRO J. Biol. Chem., October 17, 2008; 283(42): 28426 - 28435. [Abstract] [Full Text] [PDF]

				M. J. Brocker, S. Virus, S. Ganskow, P. Heathcote, D. W. Heinz, W.-D. Schubert, D. Jahn, and J. Moser ATP-driven Reduction by Dark-operative Protochlorophyllide Oxidoreductase from Chlorobium tepidum Mechanistically Resembles Nitrogenase Catalysis J. Biol. Chem., April 18, 2008; 283(16): 10559 - 10567. [Abstract] [Full Text] [PDF]

				C. Ayala-Castro, A. Saini, and F. W. Outten Fe-S Cluster Assembly Pathways in Bacteria Microbiol. Mol. Biol. Rev., March 1, 2008; 72(1): 110 - 125. [Abstract] [Full Text] [PDF]