{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,16]],"date-time":"2026-03-16T10:42:05Z","timestamp":1773657725929,"version":"3.50.1"},"reference-count":32,"publisher":"Proceedings of the National Academy of Sciences","issue":"19","content-domain":{"domain":["www.pnas.org"],"crossmark-restriction":true},"short-container-title":["Proc. Natl. Acad. Sci. U.S.A."],"published-print":{"date-parts":[[1997,9,16]]},"abstract":"<jats:p>\n            The RNA phage Q\u03b2 requires for the replication of its genome an RNA binding protein called Q\u03b2 host factor or Hfq protein. Our previous results suggested that this protein mediates the access of replicase to the 3\u2032-end of the Q\u03b2 plus strand RNA. Here we report the results of an evolutionary experiment in which phage Q\u03b2 was adapted to an\n            <jats:italic>Escherichia coli<\/jats:italic>\n            Q13 host strain with an inactivated host factor (\n            <jats:italic>hfq<\/jats:italic>\n            ) gene. This strain initially produced phage at a titer \u224810,000-fold lower than the wild-type strain and with minute plaque morphology, but after 12 growth cycles, phage titer and plaque size had evolved to levels near those of the wild-type host. RNAs isolated from adapted Q\u03b2 mutants were efficient templates for replicase without host factor\n            <jats:italic>in vitro<\/jats:italic>\n            . Electron microscopy showed that mutant RNAs, in contrast to wild-type RNA, efficiently interacted with replicase at the 3\u2032-end in the absence of host factor. The same set of four mutations in the 3\u2032-terminal third of the genome was found in several independently evolved phage clones. One mutation disrupts the base pairing of the 3\u2032-terminal CCC\n            <jats:sc>oh<\/jats:sc>\n            sequence, suggesting that the host factor stimulates activity of the wild-type RNA template by melting out its 3\u2032-end.\n          <\/jats:p>","DOI":"10.1073\/pnas.94.19.10239","type":"journal-article","created":{"date-parts":[[2002,7,26]],"date-time":"2002-07-26T14:31:44Z","timestamp":1027693904000},"page":"10239-10242","update-policy":"https:\/\/doi.org\/10.1073\/pnas.cm10313","source":"Crossref","is-referenced-by-count":54,"title":["Altered 3\u2032-terminal RNA structure in phage Q\u03b2 adapted to host factor-less\n            <i>Escherichia\u2009coli<\/i>"],"prefix":"10.1073","volume":"94","author":[{"given":"Daniel","family":"Schuppli","sequence":"first","affiliation":[{"name":"Institut f\u00fcr Molekularbiologie, Universit\u00e4t Z\u00fcrich, H\u00f6nggerberg, 8093 Z\u00fcrich, Switzerland; Department of Microbiology and Molecular Genetics, University of Texas, Houston Medical School, Houston, TX 77030; and Institut f\u00fcr Zellbiologie, Eidgen\u00f6ssische Technische Hochschule Z\u00fcrich, H\u00f6nggerberg, 8093 Z\u00fcrich, Switzerland"}]},{"given":"Giovanni","family":"Miranda","sequence":"additional","affiliation":[{"name":"Institut f\u00fcr Molekularbiologie, Universit\u00e4t Z\u00fcrich, H\u00f6nggerberg, 8093 Z\u00fcrich, Switzerland; Department of Microbiology and Molecular Genetics, University of Texas, Houston Medical School, Houston, TX 77030; and Institut f\u00fcr Zellbiologie, Eidgen\u00f6ssische Technische Hochschule Z\u00fcrich, H\u00f6nggerberg, 8093 Z\u00fcrich, Switzerland"}]},{"given":"Ho-Ching Tiffany","family":"Tsui","sequence":"additional","affiliation":[{"name":"Institut f\u00fcr Molekularbiologie, Universit\u00e4t Z\u00fcrich, H\u00f6nggerberg, 8093 Z\u00fcrich, Switzerland; Department of Microbiology and Molecular Genetics, University of Texas, Houston Medical School, Houston, TX 77030; and Institut f\u00fcr Zellbiologie, Eidgen\u00f6ssische Technische Hochschule Z\u00fcrich, H\u00f6nggerberg, 8093 Z\u00fcrich, Switzerland"}]},{"given":"Malcolm E.","family":"Winkler","sequence":"additional","affiliation":[{"name":"Institut f\u00fcr Molekularbiologie, Universit\u00e4t Z\u00fcrich, H\u00f6nggerberg, 8093 Z\u00fcrich, Switzerland; Department of Microbiology and Molecular Genetics, University of Texas, Houston Medical School, Houston, TX 77030; and Institut f\u00fcr Zellbiologie, Eidgen\u00f6ssische Technische Hochschule Z\u00fcrich, H\u00f6nggerberg, 8093 Z\u00fcrich, Switzerland"}]},{"given":"Jos\u00e9 M.","family":"Sogo","sequence":"additional","affiliation":[{"name":"Institut f\u00fcr Molekularbiologie, Universit\u00e4t Z\u00fcrich, H\u00f6nggerberg, 8093 Z\u00fcrich, Switzerland; Department of Microbiology and Molecular Genetics, University of Texas, Houston Medical School, Houston, TX 77030; and Institut f\u00fcr Zellbiologie, Eidgen\u00f6ssische Technische Hochschule Z\u00fcrich, H\u00f6nggerberg, 8093 Z\u00fcrich, Switzerland"}]},{"given":"Hans","family":"Weber","sequence":"additional","affiliation":[{"name":"Institut f\u00fcr Molekularbiologie, Universit\u00e4t Z\u00fcrich, H\u00f6nggerberg, 8093 Z\u00fcrich, Switzerland; Department of Microbiology and Molecular Genetics, University of Texas, Houston Medical School, Houston, TX 77030; and Institut f\u00fcr Zellbiologie, Eidgen\u00f6ssische Technische Hochschule Z\u00fcrich, H\u00f6nggerberg, 8093 Z\u00fcrich, Switzerland"}]}],"member":"341","published-online":{"date-parts":[[1997,9,16]]},"reference":[{"key":"e_1_3_2_1_2","doi-asserted-by":"publisher","DOI":"10.1146\/annurev.bi.48.070179.002521"},{"key":"e_1_3_2_2_2","doi-asserted-by":"publisher","DOI":"10.1007\/978-1-4684-5424-6_4"},{"key":"e_1_3_2_3_2","doi-asserted-by":"publisher","DOI":"10.1038\/228525a0"},{"key":"e_1_3_2_4_2","doi-asserted-by":"publisher","DOI":"10.1038\/228527a0"},{"key":"e_1_3_2_5_2","doi-asserted-by":"publisher","DOI":"10.1111\/j.1432-1033.1972.tb02498.x"},{"key":"e_1_3_2_6_2","doi-asserted-by":"publisher","DOI":"10.1073\/pnas.69.5.1313"},{"key":"e_1_3_2_7_2","doi-asserted-by":"publisher","DOI":"10.1016\/S0021-9258(19)42675-6"},{"key":"e_1_3_2_8_2","doi-asserted-by":"publisher","DOI":"10.1038\/219588a0"},{"key":"e_1_3_2_9_2","doi-asserted-by":"publisher","DOI":"10.1016\/S0021-9258(19)45681-0"},{"key":"e_1_3_2_10_2","doi-asserted-by":"publisher","DOI":"10.1016\/S0021-9258(19)41440-3"},{"key":"e_1_3_2_11_2","doi-asserted-by":"publisher","DOI":"10.1093\/nar\/19.5.1063"},{"key":"e_1_3_2_12_2","doi-asserted-by":"publisher","DOI":"10.1016\/0022-2836(81)90411-3"},{"key":"e_1_3_2_13_2","doi-asserted-by":"publisher","DOI":"10.1006\/jmbi.1993.1407"},{"key":"e_1_3_2_14_2","doi-asserted-by":"publisher","DOI":"10.1006\/jmbi.1997.0939"},{"key":"e_1_3_2_15_2","doi-asserted-by":"publisher","DOI":"10.1101\/gad.10.9.1143"},{"key":"e_1_3_2_16_2","doi-asserted-by":"publisher","DOI":"10.1128\/jb.178.13.3763-3770.1996"},{"key":"e_1_3_2_17_2","doi-asserted-by":"publisher","DOI":"10.1128\/jb.179.1.297-300.1997"},{"key":"e_1_3_2_18_2","doi-asserted-by":"publisher","DOI":"10.1128\/jb.179.3.656-662.1997"},{"key":"e_1_3_2_19_2","doi-asserted-by":"publisher","DOI":"10.1111\/j.1365-2958.1994.tb00400.x"},{"key":"e_1_3_2_20_2","doi-asserted-by":"publisher","DOI":"10.1006\/viro.1996.8314"},{"key":"e_1_3_2_21_2","doi-asserted-by":"publisher","DOI":"10.1016\/0378-1119(76)90004-4"},{"key":"e_1_3_2_22_2","doi-asserted-by":"publisher","DOI":"10.1073\/pnas.93.22.12256"},{"key":"e_1_3_2_23_2","volume-title":"A Short Course in Bacterial Genetics","author":"Miller J H","year":"1992","unstructured":"J H Miller A Short Course in Bacterial Genetics (Cold Spring Harbor Lab. 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