Structural Heterogeneity of Human Histone H2A.1

Area of Science:

• Biochemistry
• Structural Biology
• Biophysics

Background:

• Histones are crucial basic proteins for packaging eukaryotic DNA into nucleosomes.
• The atomic structure of nucleosomes is known, but the 3D structure of DNA-free histones is unresolved.
• Understanding histone structure is key to chromatin organization and function.

Purpose of the Study:

• To investigate the conformational landscape of DNA-free histone H2A type 1 (H2A.1).
• To correlate gas-phase structures with solution conditions using advanced analytical techniques.
• To elucidate the relationship between histone structure and its behavior in different environments.

Main Methods:

• Utilized tandem nonlinear and linear ion mobility spectrometry (FAIMS-TIMS) coupled with mass spectrometry.
• Employed molecular dynamics simulations to model histone conformations.
• Analyzed charge state distributions, mobility distributions, and collision-induced-unfolding pathways.

Main Results:

• Observed a wide range of H2A.1 gas-phase structures, from compact to elongated conformations.
• Demonstrated that gas-phase structures are dependent on initial solution conditions.
• Molecular dynamics simulations provided candidate structures for both native and gas-phase H2A.1.
• Calculations showed charge distribution differences in elongated structures correlate with FAIMS-TIMS observations.

Conclusions:

• The study successfully characterized the diverse structural states of DNA-free H2A.1.
• FAIMS-TIMS coupled with molecular modeling provides powerful insights into histone conformational dynamics.
• Findings contribute to understanding histone structural flexibility and its implications in biological processes.