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Thermodynamic origins of protein folding, allostery, and capsid formation in the human hepatitis B virus core protein.

Abstract：

:HBc, the capsid-forming "core protein" of human hepatitis B virus (HBV), is a multidomain, α-helical homodimer that aggressively forms human HBV capsids. Structural plasticity has been proposed to be important to the myriad functions HBc mediates during viral replication. Here, we report detailed thermodynamic analyses of the folding of the dimeric HBc protomer under conditions that prevented capsid formation. Central to our success was the use of ion mobility spectrometry-mass spectrometry and microscale thermophoresis, which allowed folding mechanisms to be characterized using just micrograms of protein. HBc folds in a three-state transition with a stable, dimeric, α-helical intermediate. Extensive protein engineering showed thermodynamic linkage between different structural domains. Unusual effects associated with mutating some residues suggest structural strain, arising from frustrated contacts, is present in the native dimer. We found evidence of structural gatekeepers that, when mutated, alleviated native strain and prevented (or significantly attenuated) capsid formation by tuning the population of alternative native conformations. This strain is likely an evolved feature that helps HBc access the different structures associated with its diverse essential functions. The subtle balance between native and strained contacts may provide the means to tune conformational properties of HBc by molecular interactions or mutations, thereby conferring allosteric regulation of structure and function. The ability to trap HBc conformers thermodynamically by mutation, and thereby ablate HBV capsid formation, provides proof of principle for designing antivirals that elicit similar effects.

journal_name

Proc Natl Acad Sci U S A

journal_title

Proceedings of the National Academy of Sciences of the United States of America

authors

Alexander CG,Jürgens MC,Shepherd DA,Freund SM,Ashcroft AE,Ferguson N

doi

10.1073/pnas.1308846110

subject

Has Abstract

pub_date

2013-07-23 00:00:00

pages

E2782-91

issue

eissn

0027-8424

issn

1091-6490

pii

1308846110

journal_volume

110

pub_type

杂志文章

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Thermodynamic origins of protein folding, allostery, and capsid formation in the human hepatitis B virus core protein.