{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,21]],"date-time":"2026-10-21T13:42:35Z","timestamp":1792590155616,"version":"4.5.0"},"reference-count":54,"publisher":"Wiley","license":[{"start":{"date-parts":[[2026,10,21]],"date-time":"2026-10-21T00:00:00Z","timestamp":1792540800000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"},{"start":{"date-parts":[[2026,10,21]],"date-time":"2026-10-21T00:00:00Z","timestamp":1792540800000},"content-version":"tdm","delay-in-days":0,"URL":"http:\/\/doi.wiley.com\/10.1002\/tdm_license_1.1"}],"funder":[{"DOI":"10.13039\/501100006769","name":"Russian Science Foundation","doi-asserted-by":"publisher","award":["23\u201074\u201000053"],"award-info":[{"award-number":["23\u201074\u201000053"]}],"id":[{"id":"10.13039\/501100006769","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["febs.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["The FEBS Journal"],"abstract":"<jats:p>\n                    The biogenic polyamine spermine accumulates to millimolar concentrations in proliferating cells, yet its direct effect on the 20S proteasome (\n                    <jats:ext-link xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" xlink:href=\"http:\/\/www.chem.qmul.ac.uk\/iubmb\/enzyme\/EC3\/4\/25\/1.html\">EC3.4.25.1<\/jats:ext-link>\n                    ) has remained mechanistically obscure. Here, we show that spermine directly binds and activates the human 20S proteasome through two mechanistically distinct, kinetically separable events. At low millimolar concentrations, spermine selectively stimulates the chymotrypsin\u2010like \u03b25 site up to 14\u2010fold over the basal rate, whereas above ~1.7\u2009m\n                    <jats:sc>m<\/jats:sc>\n                    it triggers a highly cooperative (Hill\n                    <jats:italic>n<\/jats:italic>\n                    \u2009=\u20098) opening of the \u03b1\u2010ring channel that additionally engages the trypsin\u2010 and caspase\u2010like sites. Simultaneous occupancy of both regions generates a hybrid enzyme form for which the catalytic constant is super\u2010additive, 163\u2010fold over\n                    <jats:italic>k<\/jats:italic>\n                    <jats:sub>cat<\/jats:sub>\n                    . The \u03b1\u2010ring transition is intrinsically slow, with channels reaching only 44% of equilibrium opening within the first 5\u2009min. Abolition of this hysteresis by SDS or by PA28\u03b1\u03b2 preloading confirms that gate opening is the rate\u2010limiting step. The combination of a high cooperative threshold (\n                    <jats:italic>K<\/jats:italic>\n                    <jats:sub>\n                      <jats:italic>ch<\/jats:italic>\n                    <\/jats:sub>\n                    \u2009~\u20091.7\u2009m\n                    <jats:sc>m<\/jats:sc>\n                    ) and slow gating kinetics defines a kinetic filter that allows the proteasome to respond selectively to sustained elevations of free polyamines, such as those characteristic of proliferating and malignant cells, while remaining insensitive to transient metabolic fluctuations. Finally, we show that spermine enhances hydrolysis of unfolded substrates by the 20S proteasome\n                    <jats:italic>in vitro<\/jats:italic>\n                    and in mammalian cells. Spermine thus emerges as the first endogenous small\u2010molecule activator that engages both the catalytic and gating layers of 20S regulation, linking polyamine metabolism directly to proteolytic capacity.\n                  <\/jats:p>","DOI":"10.1111\/febs.70761","type":"journal-article","created":{"date-parts":[[2026,10,21]],"date-time":"2026-10-21T13:02:27Z","timestamp":1792587747000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Spermine is an endogenous small\u2010molecule\n                    <scp>20S<\/scp>\n                    proteasome activator synergistically coupling chymotrypsin\u2010like active\u2010site modulation with \u03b1\u2010ring gate opening"],"prefix":"10.1111","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-2033-9621","authenticated-orcid":false,"suffix":"Jr.","given":"Alexey A.","family":"Belogurov","sequence":"first","affiliation":[{"name":"Russian Academy of Sciences Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry  Moscow Russia"},{"name":"Department of Biological Chemistry Russian University of Medicine, Ministry of Health of Russian Federation  Moscow Russia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"George A.","family":"Saratov","sequence":"additional","affiliation":[{"name":"Russian Academy of Sciences Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry  Moscow Russia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Elena V.","family":"Ilnitskaya","sequence":"additional","affiliation":[{"name":"Russian Academy of Sciences Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry  Moscow Russia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ekaterina A.","family":"Glushko","sequence":"additional","affiliation":[{"name":"Russian Academy of Sciences Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry  Moscow Russia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mikhail S.","family":"Baranov","sequence":"additional","affiliation":[{"name":"Russian Academy of Sciences Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry  Moscow Russia"},{"name":"Pirogov Russian National Research Medical University  Moscow Russia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ruslan A.","family":"Oganov","sequence":"additional","affiliation":[{"name":"Russian Academy of Sciences Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry  Moscow Russia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Darya A.","family":"Orlova","sequence":"additional","affiliation":[{"name":"Russian Academy of Sciences Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry  Moscow Russia"},{"name":"Moscow Center for Advanced Studies  Russia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yan G.","family":"Zhao","sequence":"additional","affiliation":[{"name":"Shenzhen Key Laboratory of Biomolecular Assembling and Regulation, School of Life Sciences Southern University of Science and Technology  People's Republic of China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Anna A.","family":"Kudriaeva","sequence":"additional","affiliation":[{"name":"Russian Academy of Sciences Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry  Moscow Russia"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2026,10,21]]},"reference":[{"key":"e_1_2_11_2_1","doi-asserted-by":"publisher","DOI":"10.1038\/s41568\u2010018\u20100050\u20103"},{"key":"e_1_2_11_3_1","doi-asserted-by":"publisher","DOI":"10.1152\/ajpcell.00074.2024"},{"key":"e_1_2_11_4_1","doi-asserted-by":"crossref","first-page":"20803","DOI":"10.1016\/S0021-9258(18)54780-3","article-title":"Estimation of polyamine binding to macromolecules and ATP in bovine 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