{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"institution":[{"name":"bioRxiv"}],"indexed":{"date-parts":[[2026,7,30]],"date-time":"2026-07-30T10:30:31Z","timestamp":1785407431042,"version":"3.56.0"},"posted":{"date-parts":[[2026,2,26]]},"group-title":"Biophysics","reference-count":61,"publisher":"openRxiv","license":[{"start":{"date-parts":[[2026,2,26]],"date-time":"2026-02-26T00:00:00Z","timestamp":1772064000000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc-nd\/4.0\/"}],"funder":[{"award":["GM118091"],"award-info":[{"award-number":["GM118091"]}],"id":[{"id":"https:\/\/ror.org\/04q48ey07","id-type":"ROR","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"accepted":{"date-parts":[[2026,2,26]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                <jats:p>In the sperm nucleus, protamine replaces histones to mediate extreme DNA compaction. The histone-to-protamine transition involves the occurrence of double-strand breaks, and is facilitated by transition proteins including those containing high-mobility-group (HMG) boxes. Here we used optical tweezers and microscopy to study the actions of HMGB1 and protamine on DNA. Confocal scans of GFP-HMGB1 on overstretched \u03bb-DNA show 2-3 foci that spread on the DNA upon retraction. Spreading of foci coincides with reannealing of ssDNA tracks, confirming their localization at ss-dsDNA junctions. Whereas the force\u2013extension curves of protamine-bound \u03bb-DNA show tangles that withstand forces &gt; 60 pN, premixing protamine with HMGB1 produces only bends and bridges (\u223c 20 pN). The counteraction of HMGB1 involves its acidic C-terminal tail, as HMGB1-\u0394C fails to prevent tangle formation. In line with these single-molecule results, brightfield and confocal imaging shows that HMGB1 converts protamine\u2013dsDNA aggregates into liquid droplets whereas HMGB1-\u0394C fails to do so. Together, these observations support our hypothesis that chromatin-associated proteins like HMGB1 help maintain early protamine-mediated DNA condensates in a liquid state, enabling the recruitment of the repair machinery to restore the duplex structure.<\/jats:p>","DOI":"10.64898\/2026.02.24.707832","type":"posted-content","created":{"date-parts":[[2026,2,26]],"date-time":"2026-02-26T16:10:18Z","timestamp":1772122218000},"source":"Crossref","is-referenced-by-count":0,"title":["Counteraction of HMGB1 at ss-dsDNA junctions maintains liquidity of protamine-DNA co-condensates"],"prefix":"10.64898","author":[{"given":"Vikhyaat","family":"Ahlawat","sequence":"first","affiliation":[{"name":"Department of Chemistry, University of Illinois Chicago, Chicago IL 60607, USA"},{"name":"Department of Physics, University of Illinois Chicago, Chicago IL 60607, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Divya","family":"Kota","sequence":"additional","affiliation":[{"name":"Department of Chemistry, University of Illinois Chicago, Chicago IL 60607, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9020-0302","authenticated-orcid":false,"given":"Huan-Xiang","family":"Zhou","sequence":"additional","affiliation":[{"name":"Department of Chemistry, University of Illinois Chicago, Chicago IL 60607, USA"},{"name":"Department of Physics, University of Illinois Chicago, Chicago IL 60607, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"54368","reference":[{"key":"2026030201400430000_2026.02.24.707832v1.1","doi-asserted-by":"publisher","DOI":"10.1095\/biolreprod44.4.569"},{"key":"2026030201400430000_2026.02.24.707832v1.2","doi-asserted-by":"publisher","DOI":"10.1016\/j.bbagrm.2013.08.004"},{"key":"2026030201400430000_2026.02.24.707832v1.3","doi-asserted-by":"crossref","first-page":"895502","DOI":"10.3389\/fendo.2022.895502","article-title":"The Art of Packaging the Sperm Genome: Molecular and Structural Basis of the Histone-To-Protamine Exchange","volume":"13","year":"2022","journal-title":"Front Endocrinol"},{"key":"2026030201400430000_2026.02.24.707832v1.4","doi-asserted-by":"crossref","unstructured":"Kitaoka, M. ; Yamashita, Y. 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