1MYK

CRYSTAL STRUCTURE, FOLDING, AND OPERATOR BINDING OF THE HYPERSTABLE ARC REPRESSOR MUTANT PL8

Summary for 1MYK

• Entry DOI: 10.2210/pdb1myk/pdb
• Descriptor: ARC REPRESSOR (2 entities in total)
• Functional Keywords: transcription regulation
• Biological source: Enterobacteria phage P22
• Total number of polymer chains: 2
• Total formula weight: 12508.63

Authors

Schildbach, J.F.,Milla, M.E.,Jeffrey, P.D.,Raumann, B.E.,Sauer, R.T. (deposition date: 1994-10-12, release date: 1995-01-26, Last modification date: 2024-02-14)

Primary citation

Schildbach, J.F.,Milla, M.E.,Jeffrey, P.D.,Raumann, B.E.,Sauer, R.T.
Crystal structure, folding, and operator binding of the hyperstable Arc repressor mutant PL8.
Biochemistry, 34:1405-1412, 1995

PubMed Abstract: Arc repressor is a small, dimeric DNA-binding protein that belongs to the ribbon-helix-helix family of transcription factors. Replacing Pro8 at the N-terminal end of the beta-sheet with leucine increases the stability of the mutant protein by 2.5 kcal/mol of dimer. However, this enhanced stability is achieved at the expense of significantly reduced DNA binding affinity. The structure of the PL8 mutant dimer has been determined to 2.4-A resolution by X-ray crystallography. The overall structure of the mutant is very similar to wild type, but Leu8 makes an additional interstrand hydrogen bond at each end of the beta-sheet of the mutant, increasing the total number of beta-sheet hydrogen bonds from six to eight. Comparison of the refolding and unfolding kinetics of the PL8 mutant and wild-type Arc shows that the enhanced stability of the mutant is accounted for by a decrease in the rate of protein unfolding, suggesting that the mutation acts to stabilize the native state and that the beta-sheet forms after the rate-limiting step in folding. The reduced operator affinity of the PL8 dimer appears to arise because the mutant cannot make the new interstrand hydrogen bonds and simultaneously make the wild-type set of contacts with operator DNA.

PubMed: 7827088
DOI: 10.1021/bi00004a035

Experimental method

X-RAY DIFFRACTION (2.4 Å)