{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,15]],"date-time":"2026-10-15T05:01:35Z","timestamp":1792040495075,"version":"4.4.0"},"reference-count":44,"publisher":"MDPI AG","issue":"1","license":[{"start":{"date-parts":[[2023,1,7]],"date-time":"2023-01-07T00:00:00Z","timestamp":1673049600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Japan Society for the Promotion of Science (JSPS) KAKENHI","award":["22370082"],"award-info":[{"award-number":["22370082"]}]},{"name":"Japan Society for the Promotion of Science (JSPS) KAKENHI","award":["23657157"],"award-info":[{"award-number":["23657157"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Microorganisms"],"abstract":"<jats:p>The Gram-negative bacterium Holospora obtusa is a macronucleus-specific symbiont of the ciliate Paramecium caudatum. It is known that an infection of this bacterium induces high level expressions of the host hsp60 and hsp70 genes, and the host cell acquires both heat-shock and high salt resistances. In addition, an infectious form of H. obtusa-specific 63-kDa periplasmic protein with a DNA-binding domain in its amino acid sequence is secreted into the host macronucleus after invasion into the macronucleus and remain within the nucleus. These facts suggest that binding of the 63-kDa protein to the host macronuclear DNA causes changes in the host gene expressions and enhances an environmental adaptability of the host cells. This 63-kDa protein was renamed as periplasmic region protein 1 (PRP1) to distinguish it from other proteins with similar molecular weights. To confirm whether PRP1 indeed binds to the host DNA, SDS-DNA PAGE and DNA affinity chromatography with calf thymus DNA and P. caudatum DNA were conducted and confirmed that PRP1 binds weakly to the P. caudatum DNA with a monoclonal antibody raised for the 63-kDa protein.<\/jats:p>","DOI":"10.3390\/microorganisms11010155","type":"journal-article","created":{"date-parts":[[2023,1,9]],"date-time":"2023-01-09T02:31:30Z","timestamp":1673231490000},"page":"155","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":6,"title":["A 63-kDa Periplasmic Protein of the Endonuclear Symbiotic Bacterium Holospora obtusa Secreted to the Outside of the Bacterium during the Early Infection Process Binds Weakly to the Macronuclear DNA of the Host Paramecium caudatum"],"prefix":"10.3390","volume":"11","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-2845-9158","authenticated-orcid":false,"given":"Masahiro","family":"Fujishima","sequence":"first","affiliation":[{"name":"Department of Environmental Science and Engineering, Graduate School of Science and Engineering, Yamaguchi University, Yoshida 1677-1, Yamaguchi 753-8512, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hideaki","family":"Kawano","sequence":"additional","affiliation":[{"name":"Department of Environmental Science and Engineering, Graduate School of Science and Engineering, Yamaguchi University, Yoshida 1677-1, Yamaguchi 753-8512, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Isamu","family":"Miyakawa","sequence":"additional","affiliation":[{"name":"Department of Environmental Science and Engineering, Graduate School of Science and Engineering, Yamaguchi University, Yoshida 1677-1, Yamaguchi 753-8512, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2023,1,7]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"101","DOI":"10.1016\/S0932-4739(89)80037-9","article-title":"Route of infection of bacteria Holospora elegans and Holospora obtusa into the nuclei of Paramecium caudatum","volume":"24","author":"Wiemann","year":"1989","journal-title":"Eur. 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