{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,7]],"date-time":"2026-10-07T12:57:54Z","timestamp":1791377874437,"version":"4.3.2"},"reference-count":54,"publisher":"American Society for Microbiology","issue":"1","license":[{"start":{"date-parts":[[2018,1,1]],"date-time":"2018-01-01T00:00:00Z","timestamp":1514764800000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/journals.asm.org\/non-commercial-tdm-license"}],"funder":[{"DOI":"10.13039\/100007917","name":"USDA | Agricultural Research Service","doi-asserted-by":"publisher","award":["2030-42000-050-00D"],"award-info":[{"award-number":["2030-42000-050-00D"]}],"id":[{"id":"10.13039\/100007917","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100007917","name":"USDA | Agricultural Research Service","doi-asserted-by":"publisher","award":["2030-42000-050-00D"],"award-info":[{"award-number":["2030-42000-050-00D"]}],"id":[{"id":"10.13039\/100007917","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100007917","name":"USDA | Agricultural Research Service","doi-asserted-by":"publisher","award":["5030-32000-100-00D"],"award-info":[{"award-number":["5030-32000-100-00D"]}],"id":[{"id":"10.13039\/100007917","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["journals.asm.org"],"crossmark-restriction":true},"short-container-title":["Appl Environ Microbiol"],"published-print":{"date-parts":[[2018,1]]},"abstract":"<jats:title>ABSTRACT<\/jats:title>\n          <jats:p>\n            Cah is a calcium-binding autotransporter protein involved in autoaggregation and biofilm formation. Although\n            <jats:italic>cah<\/jats:italic>\n            is widespread in Shiga toxin-producing\n            <jats:named-content content-type=\"genus-species\">Escherichia coli<\/jats:named-content>\n            (STEC), we detected mutations in\n            <jats:italic>cah<\/jats:italic>\n            at a frequency of 31.3% in this pathogen. In STEC O157:H7 supershedder strain SS17, a large deletion results in a smaller coding sequence, encoding a protein lacking the C-terminal 71 amino acids compared with Cah in STEC O157:H7 strain EDL933. We examined the function of Cah in biofilm formation and host colonization to better understand the selective pressures for\n            <jats:italic>cah<\/jats:italic>\n            mutations. EDL933-Cah played a conditional role in biofilm formation\n            <jats:italic>in vitro<\/jats:italic>\n            : it enhanced\n            <jats:named-content content-type=\"genus-species\">E. coli<\/jats:named-content>\n            DH5\u03b1 biofilm formation on glass surfaces under agitated culture conditions that prevented autoaggregation but inhibited biofilm formation under hydrostatic conditions that facilitated autoaggregation. This function appeared to be strain dependent since Cah-mediated biofilm formation was diminished when an EDL933\n            <jats:italic>cah<\/jats:italic>\n            gene was expressed in SS17. Deletion of\n            <jats:italic>cah<\/jats:italic>\n            in EDL933 enhanced bacterial attachment to spinach leaves and altered the adherence pattern of EDL933 to bovine recto-anal junction squamous epithelial (RSE) cells. In contrast, in\n            <jats:italic>trans<\/jats:italic>\n            expression of EDL933\n            <jats:italic>cah<\/jats:italic>\n            in SS17 increased its attachment to leaf surfaces, and in DH5\u03b1, it enhanced its adherence to RSE cells. Hence, the ecological function of Cah appears to be modulated by environmental conditions and other bacterial strain-specific properties. Considering the prevalence of\n            <jats:italic>cah<\/jats:italic>\n            in STEC and its role in attachment and biofilm formation,\n            <jats:italic>cah<\/jats:italic>\n            mutations might be selected in ecological niches in which inactivation of Cah would result in an increased fitness in STEC during colonization of plants or animal hosts.\n          <\/jats:p>\n          <jats:p>\n            <jats:bold>IMPORTANCE<\/jats:bold>\n            Shiga toxin-producing\n            <jats:named-content content-type=\"genus-species\">Escherichia coli<\/jats:named-content>\n            (STEC) harbors genes encoding diverse adhesins, and many of these are known to play an important role in bacterial attachment and host colonization. We demonstrated here that the autotransporter protein Cah confers on\n            <jats:named-content content-type=\"genus-species\">E. coli<\/jats:named-content>\n            DH5\u03b1 cells a strong autoaggregative phenotype that is inversely correlated with its ability to form biofilms and plays a strain-specific role in plant and animal colonization by STEC. Although\n            <jats:italic>cah<\/jats:italic>\n            is widespread in the STEC population, we detected a mutation rate of 31.3% in\n            <jats:italic>cah<\/jats:italic>\n            , which is similar to that reported for\n            <jats:italic>rpoS<\/jats:italic>\n            and\n            <jats:italic>fimH<\/jats:italic>\n            . The formation of cell aggregates due to increased bacterium-to-bacterium interactions may be disadvantageous to bacterial populations under conditions that favor a planktonic state in STEC. Therefore, a loss-of-function mutation in\n            <jats:italic>cah<\/jats:italic>\n            is likely a selective trait in STEC when autoaggregative properties become detrimental to bacterial cells and may contribute to the adaptability of STEC to fluctuating environments.\n          <\/jats:p>","DOI":"10.1128\/aem.01739-17","type":"journal-article","created":{"date-parts":[[2017,10,20]],"date-time":"2017-10-20T15:25:15Z","timestamp":1508513115000},"update-policy":"https:\/\/doi.org\/10.1128\/asmj-crossmark-policy-page","source":"Crossref","is-referenced-by-count":20,"title":["Conditional Function of Autoaggregative Protein Cah and Common\n            <i>cah<\/i>\n            Mutations in Shiga Toxin-Producing Escherichia coli"],"prefix":"10.1128","volume":"84","author":[{"given":"Michelle Qiu","family":"Carter","sequence":"first","affiliation":[{"name":"Produce Safety and Microbiology Research Unit, Western Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, Albany, California, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Maria T.","family":"Brandl","sequence":"additional","affiliation":[{"name":"Produce Safety and Microbiology Research Unit, Western Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, Albany, California, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Indira T.","family":"Kudva","sequence":"additional","affiliation":[{"name":"Food Safety and Enteric Pathogens Research Unit, National Animal Disease Center, Agricultural Research Service, U.S. Department of Agriculture, Ames, Iowa, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Robab","family":"Katani","sequence":"additional","affiliation":[{"name":"Department of Animal Science, The Pennsylvania State University, University Park, Pennsylvania, USA"},{"name":"The Huck Institutes of Life Sciences, The Pennsylvania State University, University Park, Pennsylvania, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Matthew R.","family":"Moreau","sequence":"additional","affiliation":[{"name":"Department of Veterinary and Biomedical Science, The Pennsylvania State University, University Park, Pennsylvania, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Vivek","family":"Kapur","sequence":"additional","affiliation":[{"name":"Department of Animal Science, The Pennsylvania State University, University Park, Pennsylvania, USA"},{"name":"The Huck Institutes of Life Sciences, The Pennsylvania State University, University Park, Pennsylvania, 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