{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,26]],"date-time":"2026-09-26T03:46:52Z","timestamp":1790394412468,"version":"4.1.0"},"reference-count":61,"publisher":"American Society for Microbiology","issue":"2","license":[{"start":{"date-parts":[[2016,1,15]],"date-time":"2016-01-15T00:00:00Z","timestamp":1452816000000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/journals.asm.org\/non-commercial-tdm-license"}],"funder":[{"DOI":"10.13039\/501100001691","name":"Japan Society for the Promotion of Science","doi-asserted-by":"publisher","award":["14J01576"],"award-info":[{"award-number":["14J01576"]}],"id":[{"id":"10.13039\/501100001691","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001691","name":"Japan Society for the Promotion of Science","doi-asserted-by":"publisher","award":["26713004"],"award-info":[{"award-number":["26713004"]}],"id":[{"id":"10.13039\/501100001691","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100003382","name":"Core Research for Evolutional Science and Technology, Japan Science and Technology Agency","doi-asserted-by":"publisher","award":["12101582"],"award-info":[{"award-number":["12101582"]}],"id":[{"id":"10.13039\/501100003382","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["journals.asm.org"],"crossmark-restriction":true},"short-container-title":["J Bacteriol"],"published-print":{"date-parts":[[2016,1,15]]},"abstract":"<jats:title>ABSTRACT<\/jats:title>\n                  <jats:p>\n                    The AcrAB-TolC system in\n                    <jats:named-content xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" content-type=\"genus-species\" xlink:type=\"simple\">Escherichia coli<\/jats:named-content>\n                    is an intrinsic RND-type multidrug efflux transporter that functions as a tripartite complex of the inner membrane transporter AcrB, the outer membrane channel TolC, and the adaptor protein AcrA. Although the crystal structures of each component of this system have been elucidated, the crystal structure of the whole complex has not been solved. The available crystal structures have shown that AcrB and TolC function as trimers, but the number of AcrA molecules in the complex is now under debate. Disulfide chemical cross-linking experiments have indicated that the stoichiometry of AcrB-AcrA-TolC is 1:1:1; on the other hand, recent cryo-electron microscopy images of AcrAB-TolC suggested a 1:2:1 stoichiometry. In this study, we constructed 1:1-fixed AcrB-AcrA fusion proteins using various linkers. Surprisingly, all the 1:1-fixed linker proteins showed drug export activity under both\n                    <jats:italic>acrAB<\/jats:italic>\n                    -deficient conditions and\n                    <jats:italic>acrAB acrEF<\/jats:italic>\n                    double-pump-knockout conditions regardless of the lengths of the linkers. Finally, we optimized a shorter linker lacking the conformational freedom imparted by the AcrB C terminus. These results suggest that a complex with equal amounts of AcrA and AcrB is sufficient for drug export function.\n                  <\/jats:p>\n                  <jats:p>\n                    <jats:bold>IMPORTANCE<\/jats:bold>\n                    The structure and stoichiometry of the RND-type multidrug exporter AcrB-AcrA-TolC complex are still under debate. Recently, electron microscopic images of the AcrB-AcrA-TolC complex have been reported, suggesting a 1:2:1 stoichiometry. However, we report here that the AcrB-AcrA 1:1 fusion protein is active for drug export under\n                    <jats:italic>acrAB<\/jats:italic>\n                    -deficient conditions and also under\n                    <jats:italic>acrAB<\/jats:italic>\n                    <jats:italic>acrEF<\/jats:italic>\n                    double-deficient conditions, which eliminate the aid of free AcrA and its close homolog AcrE, indicating that the AcrB-AcrA 1:1 stoichiometry is enough for drug export function. In addition, the AcrB-AcrA fusion protein can function without the aid of free AcrA. We believe that these results are very important for considering the structure and mechanism of AcrAB-TolC-mediated multidrug export.\n                  <\/jats:p>","DOI":"10.1128\/jb.00587-15","type":"journal-article","created":{"date-parts":[[2015,11,2]],"date-time":"2015-11-02T22:13:49Z","timestamp":1446502429000},"page":"332-342","update-policy":"https:\/\/doi.org\/10.1128\/asmj-crossmark-policy-page","source":"Crossref","is-referenced-by-count":42,"title":["AcrB-AcrA Fusion Proteins That Act as Multidrug Efflux Transporters"],"prefix":"10.1128","volume":"198","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-7359-5939","authenticated-orcid":false,"given":"Katsuhiko","family":"Hayashi","sequence":"first","affiliation":[{"name":"Graduate School of Pharmaceutical Sciences, Osaka University, Suita, Japan"},{"name":"The Institute of Scientific and Industrial Research (ISIR), Osaka University, Ibaraki, Osaka, Japan"},{"name":"Japan Society for the Promotion of Science, Tokyo, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ryosuke","family":"Nakashima","sequence":"additional","affiliation":[{"name":"The Institute of Scientific and Industrial Research (ISIR), Osaka University, Ibaraki, Osaka, Japan"},{"name":"CREST, Japan Science and Technology Agency, Saitama, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Keisuke","family":"Sakurai","sequence":"additional","affiliation":[{"name":"The Institute of Scientific and Industrial Research (ISIR), Osaka University, Ibaraki, Osaka, Japan"},{"name":"CREST, Japan Science and Technology Agency, Saitama, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kimie","family":"Kitagawa","sequence":"additional","affiliation":[{"name":"The Institute of Scientific and Industrial Research (ISIR), Osaka University, Ibaraki, Osaka, 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