1b01
From Proteopedia
|
TRANSCRIPTIONAL REPRESSOR COPG/DNA COMPLEX
Overview
The structure of the 45 amino acid transcriptional repressor, CopG, has, been solved unliganded and bound to its target operator DNA. The protein, encoded by the promiscuous streptococcal plasmid pMV158, is involved in, the control of plasmid copy number. The structure of this protein, repressor, which is the shortest reported to date and the first isolated, from a plasmid, has a homodimeric ribbon-helix-helix arrangement. It is, the prototype for a family of homologous plasmid repressors. CopG, cooperatively associates, completely protecting several turns on one face, of the double helix in both directions from a 13-bp pseudosymmetric, primary DNA recognition element. In the complex structure, one protein, tetramer binds at one face of a 19-bp oligonucleotide, containing the, pseudosymmetric element, with two beta-ribbons inserted into the major, groove. The DNA is bent 60 degrees by compression of both major and minor, grooves. The protein dimer displays topological similarity to Arc and MetJ, repressors. Nevertheless, the functional tetramer has a unique structure, with the two vicinal recognition ribbon elements at a short distance, thus, inducing strong DNA bend. Further structural resemblance is found with, helix-turn-helix regions of unrelated DNA-binding proteins. In contrast to, these, however, the bihelical region of CopG has a role in oligomerization, instead of DNA recognition. This observation unveils an evolutionary link, between ribbon-helix-helix and helix-turn-helix proteins.
About this Structure
1B01 is a Single protein structure of sequence from Streptococcus agalactiae. Full crystallographic information is available from OCA.
Reference
The structure of plasmid-encoded transcriptional repressor CopG unliganded and bound to its operator., Gomis-Ruth FX, Sola M, Acebo P, Parraga A, Guasch A, Eritja R, Gonzalez A, Espinosa M, del Solar G, Coll M, EMBO J. 1998 Dec 15;17(24):7404-15. PMID:9857196
Page seeded by OCA on Tue Nov 20 11:14:40 2007
