Frontiers in microbiology · 2026
Investigation of salt-bridge interactions underlying salt activation of halophilic methionine sulfoxide reductase A.
СтатьяНазвание и аннотация: Перевод в очереди
Обработка статьи · этапы, ошибки и управление
Загрузка состояния…
Ошибки и ограничения
История · было → стало
Состояние обновляется каждые 5 секунд, пока блок открыт. Процент показывается только там, где известен объём работы. Пауза останавливает продолжение этапа; текущий запрос к источнику может завершиться.
Chen Shuhong, Liu Lianghui, Zhou Hailang, Kuang Xiaoxue, Li Ye, Liu Rong, Yang Jiawei, Cheng Xiaoling
Аннотация
INTRODUCTION: Halophilic microorganisms inhabit hypersaline environments where sustained ionic stress challenges protein structure and function, making salt-responsive enzymes important for cellular fitness. Here, we investigated the salt-bridge interactions that support salt-dependent activation of a halophilic methionine sulfoxide reductase A from Halobacterium hubeiense (HhMsrA), a key enzyme involved in repairing oxidized methionine residues.
METHODS: Molecular dynamics (MD) simulations, mutagenesis analyses, enzyme activity assays, and circular dichroism (CD) measurements were used to identify key salt-bridge-forming residues and evaluate their contributions to the salt-dependent structural and functional behavior of HhMsrA.
RESULTS: MD simulations and mutagenesis analyses identified Arg106 and Lys76 as prominent salt-bridge nodes, and charge-conservative substitutions at these positions largely preserved the high-salt activity profile, whereas non-conservative substitutions (e.g., acidic, hydrophobic, aromatic, or proline replacements) generally reduced activity. Moreover, combined proline substitutions produced a pronounced cumulative effect, leaving the enzyme with only minimal activity even under high-salt conditions. MD analyses further associated these site-specific salt-bridge interactions with the maintenance of the salt-adapted structural state required for HhMsrA activity. CD measurements further showed a strong KCl-dependent helical response in HhMsrA that was attenuated to varying degrees across mutants targeting salt-bridge-forming residues.
DISCUSSION: These findings demonstrate that salt-dependent activity of HhMsrA is supported by a small set of salt-bridge nodes that contribute to maintaining a high-salt structural state compatible with HhMsrA catalytic function.
METHODS: Molecular dynamics (MD) simulations, mutagenesis analyses, enzyme activity assays, and circular dichroism (CD) measurements were used to identify key salt-bridge-forming residues and evaluate their contributions to the salt-dependent structural and functional behavior of HhMsrA.
RESULTS: MD simulations and mutagenesis analyses identified Arg106 and Lys76 as prominent salt-bridge nodes, and charge-conservative substitutions at these positions largely preserved the high-salt activity profile, whereas non-conservative substitutions (e.g., acidic, hydrophobic, aromatic, or proline replacements) generally reduced activity. Moreover, combined proline substitutions produced a pronounced cumulative effect, leaving the enzyme with only minimal activity even under high-salt conditions. MD analyses further associated these site-specific salt-bridge interactions with the maintenance of the salt-adapted structural state required for HhMsrA activity. CD measurements further showed a strong KCl-dependent helical response in HhMsrA that was attenuated to varying degrees across mutants targeting salt-bridge-forming residues.
DISCUSSION: These findings demonstrate that salt-dependent activity of HhMsrA is supported by a small set of salt-bridge nodes that contribute to maintaining a high-salt structural state compatible with HhMsrA catalytic function.