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| {{STRUCTURE_1o57| PDB=1o57 | SCENE= }} | | {{STRUCTURE_1o57| PDB=1o57 | SCENE= }} |
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| '''CRYSTAL STRUCTURE OF THE PURINE OPERON REPRESSOR OF BACILLUS SUBTILIS'''
| | ===CRYSTAL STRUCTURE OF THE PURINE OPERON REPRESSOR OF BACILLUS SUBTILIS=== |
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| ==Overview==
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| 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. | | The line below this paragraph, {{ABSTRACT_PUBMED_12837783}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 12837783 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_12837783}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Purine operon repressor]] | | [[Category: Purine operon repressor]] |
| [[Category: Transcription regulation]] | | [[Category: Transcription regulation]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 03:23:47 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jul 28 13:20:11 2008'' |