1KCA

Crystal Structure of the lambda Repressor C-terminal Domain Octamer

Summary for 1KCA

• Entry DOI: 10.2210/pdb1kca/pdb
• Descriptor: REPRESSOR PROTEIN CI (1 entity in total)
• Functional Keywords: gene regulation, dna-binding, lambda repressor, protein oligomerization, dna-looping
• Biological source: Enterobacteria phage lambda
• Total number of polymer chains: 8
• Total formula weight: 94795.04

Authors

Bell, C.E.,Lewis, M. (deposition date: 2001-11-07, release date: 2001-12-21, Last modification date: 2024-10-30)

Primary citation

Bell, C.E.,Lewis, M.
Crystal structure of the lambda repressor C-terminal domain octamer.
J.Mol.Biol., 314:1127-1136, 2001

PubMed Abstract: 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.

PubMed: 11743728
DOI: 10.1006/jmbi.2000.5196

Experimental method

X-RAY DIFFRACTION (2.91 Å)