Crystal structure, folding, and operator binding of the hyperstable Arc repressor mutant PL8.


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. Study holds ProTherm entries: 889, 890, 891, 892, 893, 894, 13448 Extra Details: additive : EDTA(0.2 mM), Arc repressor; DNA binding affinity; hydrogen bond;,kinetics; stability

Submission Details

ID: Qx3Lzt9K

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:16 p.m.

Version: 1

Publication Details
Schildbach JF;Milla ME;Jeffrey PD;Raumann BE;Sauer RT,Biochemistry (1995) Crystal structure, folding, and operator binding of the hyperstable Arc repressor mutant PL8. PMID:7827088
Additional Information

Structure view and single mutant data analysis

Study data

No weblogo for data of varying length.
Colors: D E R H K S T N Q A V I L M F Y W C G P

Data Distribution

Studies with similar sequences (approximate matches)

Correlation with other assays (exact sequence matches)

Relevant UniProtKB Entries

Percent Identity Matching Chains Protein Accession Entry Name
100.0 Transcriptional repressor arc P03050 RARC_BPP22