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Full-Text Articles in Physical Sciences and Mathematics
Mutational Studies Uncover Non-Native Structure In The Dimeric Kinetic Intermediate Of The H2a–H2b Heterodimer, Matthew R. Stump, Lisa M. Gloss
Mutational Studies Uncover Non-Native Structure In The Dimeric Kinetic Intermediate Of The H2a–H2b Heterodimer, Matthew R. Stump, Lisa M. Gloss
Faculty Publications - Department of Biological & Molecular Science
The folding pathway of the histone H2A–H2B heterodimer minimally includes an on-pathway, dimeric, burst-phase intermediate, I2. The partially folded H2A and H2B monomers populated at equilibrium were characterized as potential monomeric kinetic intermediates. Folding kinetics were compared for initiation from isolated, folded monomers and the heterodimer unfolded in 4 M urea. The observed rates were virtually identical above 0.4Murea, exhibiting a log-linear relationship on the final denaturant concentration. Below ∼0.4 M urea (concentrations inaccessible from the 4-M urea unfolded state), a rollover in the rates was observed; this suggests that a component of the I2 ensemble contains non-native structure that …
Mutational Analysis Of The Stability Of The H2a And H2b Histone Monomers, Matthew R. Stump, Lisa M. Gloss
Mutational Analysis Of The Stability Of The H2a And H2b Histone Monomers, Matthew R. Stump, Lisa M. Gloss
Faculty Publications - Department of Biological & Molecular Science
The eukaryotic histone heterodimer H2A–H2B folds through an obligatory dimeric intermediate that forms in a nearly diffusion-limited association reaction in the stopped-flow dead time. It is unclear whether there is partial folding of the isolated monomers before association. To address the possible contributions of structure in the monomers to the rapid association, we characterized H2A and H2B monomers in the absence of their heterodimeric partner. By far-UV circular dichroism, the H2A and H2B monomers are 15% and 31% helical, respectively—significantly less than observed in X-ray crystal structures. Acrylamide quenching of the intrinsic Tyr fluorescence was indicative of tertiary structure. The …