1kca
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Crystal Structure of the lambda Repressor C-terminal Domain Octamer
OverviewOverview
The three-dimensional structure of the lambda repressor C-terminal domain, (CTD) has been determined at atomic resolution. In the crystal, the CTD, forms a 2-fold symmetric tetramer that mediates cooperative binding of two, repressor dimers to pairs of operator sites. Based upon this structure, a, model was proposed for the structure of an octameric repressor that forms, both in the presence and absence of DNA. Here, we have determined the, structure of the lambda repressor CTD in three new crystal forms, under a, wide variety of conditions. All crystals have essentially the same, tetramer, confirming the results of the earlier study. One crystal form, has two tetramers bound to form an octamer, which has the same overall, architecture as the previously proposed model. An unexpected feature of, the octamer in the crystal structure is a unique interaction at the, tetramer-tetramer interface, formed by residues Gln209, Tyr210 and Pro211, which contact symmetry-equivalent residues from other subunits of the, octamer. Interestingly, these residues are also located at the dimer-dimer, interface, where the specific interactions are different. The structures, thus indicate specific amino acid residues that, at least in principle, when altered could result in repressors that form tetramers but not, octamers.
About this StructureAbout this Structure
1KCA is a Single protein structure of sequence from Enterobacteria phage lambda. Full crystallographic information is available from OCA.
ReferenceReference
Crystal structure of the lambda repressor C-terminal domain octamer., Bell CE, Lewis M, J Mol Biol. 2001 Dec 14;314(5):1127-36. PMID:11743728
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