Structure and stability of the N-terminal domain of the ribosomal protein L9: evidence for rapid two-state folding.


The N-terminal domain, residues 1-56, of the ribosomal protein L9 has been chemically synthesized. The isolated domain is monomeric as judged by analytical ultracentrifugation and concentration-dependent CD. Complete 1H chemical shift assignments were obtained using standard methods. 2D-NMR experiments show that the isolated domain adopts the same structure as seen in the full-length protein. It consists of a three-stranded antiparallel beta-sheet sandwiched between two helixes. Thermal and urea unfolding transitions are cooperative, and the unfolding curves generated from different experimental techniques, 1D-NMR, far-UV CD, near-UV CD, and fluorescence, are superimposable. These results suggest that the protein folds by a two-state mechanism. The thermal midpoint of folding is 77 +/- 2 degrees C at pD 8.0, and the domain has a delta G degree folding = 2.8 +/- 0.8 kcal/mol at 40 degrees C, pH 7.0. Near the thermal midpoint of the unfolding transition, the 1D-NMR peaks are significantly broadened, indicating that folding is occurring on the intermediate exchange time scale. The rate of folding was determined by fitting the NMR spectra to a two-state chemical exchange model. Similar folding rates were measured for Phe 5, located in the first beta-strand, and for Tyr 25, located in the short helix between strands two and three. The domain folds extremely rapidly with a folding rate constant of 2000 s-1 near the midpoint of the equilibrium thermal unfolding transition. Study holds ProTherm entries: 8825, 8826, 8827 Extra Details: antiparallel beta-sheet; cooperative; two-state mechanism;,equilibrium thermal unfolding transition

Submission Details

ID: MeJmhRyk

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:37 p.m.

Version: 1

Publication Details
Kuhlman B;Boice JA;Fairman R;Raleigh DP,Biochemistry (1998) Structure and stability of the N-terminal domain of the ribosomal protein L9: evidence for rapid two-state folding. PMID:9454593
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 50S ribosomal protein L9 P02417 RL9_GEOSE
96.6 50S ribosomal protein L9 A4ITV1 RL9_GEOTN
95.3 50S ribosomal protein L9 Q5KU74 RL9_GEOKA