1per

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spinqualitylabelsall models 1per, resolution 2.500Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

THE COMPLEX BETWEEN PHAGE 434 REPRESSION DNA-BINDING DOMAIN AND OPERATOR SITE OR3: STRUCTURAL DIFFERENCES BETWEEN CONSENSUS AND NON-CONSENSUS HALF-SITES

Overview

BACKGROUND: The repressor of phage 434 binds to a set of operator sites as, a homodimer. Its relative affinities for these sites determine the switch, from lysogenic to lytic growth. The six 434 operator sites (OR1, OR2, OR3, OL1, OL2 and OL3) have a particularly simple organization; all are 14 base, pairs long, with a conserved 5'-ACAA sequence symmetrically placed at, either end, and a variable central six base pairs. OR3 is unique among, naturally-occurring 434 operator sites in that it contains a non-consensus, base pair, G.C, at the fourth position of the otherwise invariant 5'-ACAA, sequence. Comparisons among structures of the 434 repressor DNA-binding, domain, R1-69, bound to various operator sites, allow us to analyze, differential specificity in regulatory complexes of this kind. RESULTS: We, have determined the structure at 2.5 A resolution of a complex of R1-69, with DNA containing the OR3 site and compared it with previously studied, complexes of R1-69 bound to OR1 and OR2. There are surprisingly extensive, structural differences between the consensus and non-consensus half-sites, of OR3 with respect to their interactions with R1-69, including a shift in, the DNA backbone and a small rotation of the entire R1-69 monomer., CONCLUSIONS: Recognition of the base pair difference that is critical for, the 434 regulatory switch involves a number of amino acid residues, not, just the one or two side chains in direct contact with the G-C base pair., Moreover, the repressor imposes a somewhat altered DNA conformation on the, non-consensus half-site.

About this Structure

1PER is a Single protein structure of sequence from Bacteriophage 434. Full crystallographic information is available from OCA.

Reference

The complex between phage 434 repressor DNA-binding domain and operator site OR3: structural differences between consensus and non-consensus half-sites., Rodgers DW, Harrison SC, Structure. 1993 Dec 15;1(4):227-40. PMID:8081737

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