Unknown

Dataset Information

0

Unique fluorophores in the dimeric archaeal histones hMfB and hPyA1 reveal the impact of nonnative structure in a monomeric kinetic intermediate.


ABSTRACT: Homodimeric archaeal histones and heterodimeric eukaryotic histones share a conserved structure but fold through different kinetic mechanisms, with a correlation between faster folding/association rates and the population of kinetic intermediates. Wild-type hMfB (from Methanothermus fervidus) has no intrinsic fluorophores; Met35, which is Tyr in hyperthermophilic archaeal histones such as hPyA1 (from Pyrococcus strain GB-3A), was mutated to Tyr and Trp. Two Tyr-to-Trp mutants of hPyA1 were also characterized. All fluorophores were introduced into the long, central alpha-helix of the histone fold. Far-UV circular dichroism (CD) indicated that the fluorophores did not significantly alter the helical content of the histones. The equilibrium unfolding transitions of the histone variants were two-state, reversible processes, with DeltaG degrees (H2O) values within 1 kcal/mol of the wild-type dimers. The hPyA1 Trp variants fold by two-state kinetic mechanisms like wild-type hPyA1, but with increased folding and unfolding rates, suggesting that the mutated residues (Tyr-32 and Tyr-36) contribute to transition state structure. Like wild-type hMfB, M35Y and M35W hMfB fold by a three-state mechanism, with a stopped-flow CD burst-phase monomeric intermediate. The M35 mutants populate monomeric intermediates with increased secondary structure and stability but exhibit decreased folding rates; this suggests that nonnative interactions occur from burial of the hydrophobic Tyr and Trp residues in this kinetic intermediate. These results implicate the long central helix as a key component of the structure in the kinetic monomeric intermediates of hMfB as well as the dimerization transition state in the folding of hPyA1.

SUBMITTER: Stump MR 

PROVIDER: S-EPMC2222717 | biostudies-literature | 2008 Feb

REPOSITORIES: biostudies-literature

altmetric image

Publications

Unique fluorophores in the dimeric archaeal histones hMfB and hPyA1 reveal the impact of nonnative structure in a monomeric kinetic intermediate.

Stump Matthew R MR   Gloss Lisa M LM  

Protein science : a publication of the Protein Society 20071220 2


Homodimeric archaeal histones and heterodimeric eukaryotic histones share a conserved structure but fold through different kinetic mechanisms, with a correlation between faster folding/association rates and the population of kinetic intermediates. Wild-type hMfB (from Methanothermus fervidus) has no intrinsic fluorophores; Met35, which is Tyr in hyperthermophilic archaeal histones such as hPyA1 (from Pyrococcus strain GB-3A), was mutated to Tyr and Trp. Two Tyr-to-Trp mutants of hPyA1 were also  ...[more]

Similar Datasets

| S-EPMC7846606 | biostudies-literature
| S-EPMC6136690 | biostudies-literature
| S-EPMC2914809 | biostudies-literature
| S-EPMC6867714 | biostudies-literature
| S-EPMC3265876 | biostudies-literature
| S-EPMC3259194 | biostudies-literature
| S-EPMC3499341 | biostudies-literature
2021-01-19 | GSE117661 | GEO
| S-EPMC7012074 | biostudies-literature
| S-EPMC6317722 | biostudies-literature