1o57
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CRYSTAL STRUCTURE OF THE PURINE OPERON REPRESSOR OF BACILLUS SUBTILIS
OverviewOverview
The purine repressor from Bacillus subtilis, PurR, represses transcription, from a number of genes with functions in the synthesis, transport, and, metabolism of purines. The 2.2-A crystal structure of PurR reveals a, two-domain protein organized as a dimer. The larger C-terminal domain, belongs to the PRT structural family, in accord with a sequence motif for, binding the inducer phosphoribosylpyrophosphate (PRPP). The PRT domain is, fused to a smaller N-terminal domain that belongs to the winged-helix, family of DNA binding proteins. A positively charged surface on the, winged-helix domain likely binds specific DNA sequences in the recognition, site. A second positively charged surface surrounds the PRPP site at the, opposite end of the PurR dimer. Conserved amino acids in the sequences of, PurR homologs in 21 gram-positive bacteria cluster on the proposed, recognition surface of the winged-helix domain and around the PRPP binding, site at the opposite end of the molecule, supporting a common function of, DNA and PRPP binding for all of the proteins. The structure supports a, binding mechanism in which extended regions of DNA interact with extensive, protein surface. Unlike most PRT proteins, which are, phosphoribosyltransferases (PRTases), PurR lacks catalytic activity. This, is explained by a tyrosine side chain that blocks the site for a, nucleophile cosubstrate in PRTases. Thus, B. subtilis has adapted an, enzyme fold to serve as an effector-binding domain and has used it in a, novel combination with the DNA-binding winged-helix domain as a repressor, of purine genes.
About this StructureAbout this Structure
1O57 is a Single protein structure of sequence from Bacillus subtilis with SO4, EPE, P6G, 2PE, PG4 and 1PE as ligands. This structure superseeds the now removed PDB entry 1P41. Full crystallographic information is available from OCA.
ReferenceReference
The purine repressor of Bacillus subtilis: a novel combination of domains adapted for transcription regulation., Sinha SC, Krahn J, Shin BS, Tomchick DR, Zalkin H, Smith JL, J Bacteriol. 2003 Jul;185(14):4087-98. PMID:12837783
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