{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,27]],"date-time":"2026-08-27T18:24:38Z","timestamp":1787855078512,"version":"build-2784847793"},"reference-count":39,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,8,24]],"date-time":"2026-08-24T00:00:00Z","timestamp":1787529600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Microbiol."],"abstract":"<jats:sec>\n                    <jats:title>Introduction<\/jats:title>\n                    <jats:p>\n                      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\n                      <jats:italic>Halobacterium hubeiense<\/jats:italic>\n                      (\n                      <jats:italic>Hh<\/jats:italic>\n                      MsrA), a key enzyme involved in repairing oxidized methionine residues.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>\n                      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\n                      <jats:italic>Hh<\/jats:italic>\n                      MsrA.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      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\n                      <jats:italic>Hh<\/jats:italic>\n                      MsrA activity. CD measurements further showed a strong KCl-dependent helical response in\n                      <jats:italic>Hh<\/jats:italic>\n                      MsrA that was attenuated to varying degrees across mutants targeting salt-bridge-forming residues.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Discussion<\/jats:title>\n                    <jats:p>\n                      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\n                      <jats:italic>Hh<\/jats:italic>\n                      MsrA catalytic function.\n                    <\/jats:p>\n                  <\/jats:sec>","DOI":"10.3389\/fmicb.2026.1907662","type":"journal-article","created":{"date-parts":[[2026,8,24]],"date-time":"2026-08-24T04:23:33Z","timestamp":1787545413000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["Investigation of salt-bridge interactions underlying salt activation of halophilic methionine sulfoxide reductase A"],"prefix":"10.3389","volume":"17","author":[{"given":"Shuhong","family":"Chen","sequence":"first","affiliation":[{"name":"Department of Biochemistry, School of Preclinical Medicine, Zunyi Medical University","place":["Zunyi, Guizhou, China"]},{"name":"Department of Clinical Laboratory, Guizhou Aerospace Hospital","place":["Zunyi, Guizhou, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lianghui","family":"Liu","sequence":"additional","affiliation":[{"name":"Department of Biochemistry, School of Preclinical Medicine, Zunyi Medical University","place":["Zunyi, Guizhou, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hailang","family":"Zhou","sequence":"additional","affiliation":[{"name":"Department of Biochemistry, School of Preclinical Medicine, Zunyi Medical University","place":["Zunyi, Guizhou, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xiaoxue","family":"Kuang","sequence":"additional","affiliation":[{"name":"Department of Biochemistry, School of Preclinical Medicine, Zunyi Medical University","place":["Zunyi, Guizhou, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ye","family":"Li","sequence":"additional","affiliation":[{"name":"Department of Biochemistry, School of Preclinical Medicine, Zunyi Medical University","place":["Zunyi, Guizhou, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Rong","family":"Liu","sequence":"additional","affiliation":[{"name":"Department of Biochemistry, School of Preclinical Medicine, Zunyi Medical University","place":["Zunyi, Guizhou, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jiawei","family":"Yang","sequence":"additional","affiliation":[{"name":"Department of Biochemistry, School of Preclinical Medicine, Zunyi Medical University","place":["Zunyi, Guizhou, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xiaoling","family":"Cheng","sequence":"additional","affiliation":[{"name":"Department of Cell Biology, School of Preclinical Medicine, Zunyi Medical University","place":["Zunyi, Guizhou, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2026,8,24]]},"reference":[{"key":"ref1","doi-asserted-by":"publisher","first-page":"19","DOI":"10.1016\/j.softx.2015.06.001","article-title":"GROMACS: high performance molecular simulations through multi-level parallelism from laptops to supercomputers","volume":"1","author":"Abraham","year":"2015","journal-title":"SoftwareX"},{"key":"ref2","doi-asserted-by":"publisher","first-page":"665492","DOI":"10.3389\/fmolb.2021.665492","article-title":"Methionine redox homeostasis in protein quality control","volume":"8","author":"Aussel","year":"2021","journal-title":"Front. 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