1yy7

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Revision as of 02:31, 25 November 2007

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spinqualitylabelsall models 1yy7, resolution 2.020Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

Crystal structure of stringent starvation protein A (SspA), an RNA polymerase-associated transcription factor

Overview

Stringent starvation protein A (SspA) of Escherichia coli is an RNA, polymerase-associated transcriptional activator for the lytic development, of phage P1 and is essential for stationary phase-induced acid tolerance, of E. coli. We report the crystal structure of Yersinia pestis SspA, which, is 83% identical to E. coli SspA in amino acid sequence and is, functionally complementary in supporting the lytic growth of phage P1 and, acid resistance of an E. coli sspA mutant. The structure reveals that SspA, assumes the characteristic fold of glutathione S-transferase (GST)., However, SspA lacks GST activity and does not bind glutathione. Three, regions of SspA are flexible, the N and C termini and the alpha2-helix., The structure also reveals a conserved surface-exposed pocket composed of, residues from a loop between helices alpha3 and alpha4. The functional, roles of these structural features were investigated by assessing the, ability of deletion and site-directed mutants to confer acid resistance of, E. coli and to activate transcription from a phage P1 late promoter, thereby supporting the lytic growth of phage P1. The results indicate that, the flexible regions are not critical for SspA function, whereas the, surface pocket is important for both transcriptional activation of the, phage P1 late promoter and acid resistance of E. coli. The size, shape, and property of the pocket suggest that it mediates protein-protein, interactions. SspA orthologs from Y. pestis, Vibrio cholerae, and, Pseudomonas aeruginosa are all functional in acid resistance of E. coli, whereas only Y. pestis SspA supports phage P1 growth.

About this Structure

1YY7 is a Single protein structure of sequence from Yersinia pestis with CIT as ligand. Full crystallographic information is available from OCA.

Reference

Structural basis for the function of stringent starvation protein a as a transcription factor., Hansen AM, Gu Y, Li M, Andrykovitch M, Waugh DS, Jin DJ, Ji X, J Biol Chem. 2005 Apr 29;280(17):17380-91. Epub 2005 Feb 25. PMID:15735307

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