{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"institution":[{"name":"bioRxiv"}],"indexed":{"date-parts":[[2026,9,17]],"date-time":"2026-09-17T04:05:04Z","timestamp":1789617904755,"version":"build-2803163510"},"posted":{"date-parts":[[2026,9,11]]},"group-title":"Microbiology","reference-count":27,"publisher":"openRxiv","license":[{"start":{"date-parts":[[2026,9,11]],"date-time":"2026-09-11T00:00:00Z","timestamp":1789084800000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc-nd\/4.0\/"}],"funder":[{"name":"National Institutes of Health","award":["AI168157"],"award-info":[{"award-number":["AI168157"]}]},{"name":"National Institutes of Health","award":["AI128164"],"award-info":[{"award-number":["AI128164"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"accepted":{"date-parts":[[2026,9,11]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                <jats:p>\n                  CexE is an outer membrane lipoprotein of enterotoxigenic\n                  <jats:italic>Escherichia coli<\/jats:italic>\n                  (ETEC); one of the most prevalent etiological agents of diarrheal disease. Homologs of CexE are present in enteroaggregative\n                  <jats:italic>E. coli<\/jats:italic>\n                  ,\n                  <jats:italic>Citrobacter rodentium<\/jats:italic>\n                  , and other enteropathogens. We have previously shown that expression of CexE is dependent upon Rns, the master virulence regulator of ETEC and a member of the AraC\/XylS superfamily of transcription factors. In this study we report that the expression of\n                  <jats:italic>cexD<\/jats:italic>\n                  and\n                  <jats:italic>cexPABC<\/jats:italic>\n                  , the genes required for lipidation and delivery of CexE to the outer leaflet of the outer membrane, are also Rns-dependent. Although\n                  <jats:italic>cexE<\/jats:italic>\n                  and\n                  <jats:italic>cexPABC<\/jats:italic>\n                  are arranged in the same orientation, they are separated by an intergenic region sufficiently large to accommodate a promoter and transcription factor binding sites. Nevertheless, expression of the four gene cluster does not originate within the intergenic region. Rather,\n                  <jats:italic>cexPABC<\/jats:italic>\n                  are expressed from the Rns-dependent\n                  <jats:italic>cexE<\/jats:italic>\n                  promoter. The remaining gene of the system,\n                  <jats:italic>cexD<\/jats:italic>\n                  , is monocistronic and expressed from its own Rns-dependent promoter. Mutagenesis of a predicted Rns binding site upstream of\n                  <jats:italic>cexD<\/jats:italic>\n                  abolished Rns binding to a\n                  <jats:italic>cexD<\/jats:italic>\n                  promoter fragment in vitro and activation of the promoter in vivo. CexD is a novel bacterial acyltransferase. Unlike canonical bacterial acyltransferases that lipidate amino-terminal cysteines, CexD attaches a lipid to the amino-terminal glycine of CexE. Lipidation must occur in the periplasm because topological mapping revealed that CexD has six transmembrane domains with both its amino-terminus and enzymatic domain in the periplasm. We further show that CexD is required for CexE\u2019s localization to the outer leaflet of the outer membrane and that a\n                  <jats:italic>cexD<\/jats:italic>\n                  mutant of\n                  <jats:italic>C. rodentium<\/jats:italic>\n                  is attenuated in a murine model. These findings further define the Rns virulence regulon, the enzymology of a noncanonical acyltranferase and its contributions to pathogenicity.\n                <\/jats:p>","DOI":"10.64898\/2026.09.11.750658","type":"posted-content","created":{"date-parts":[[2026,9,12]],"date-time":"2026-09-12T03:40:23Z","timestamp":1789184423000},"source":"Crossref","is-referenced-by-count":0,"title":["Regulation and Characterization of the Cex system of enteric pathogens: a pathway for the lipidation and secretion of noncanoncial bacterial lipoproteins"],"prefix":"10.64898","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-2428-5541","authenticated-orcid":false,"given":"Zachary P.","family":"Rivas","sequence":"first","affiliation":[{"name":"University of Miami Miller School of Medicine, Department of Microbiology and Immunology, Miami, Florida, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9146-0445","authenticated-orcid":false,"given":"Kacey M.","family":"Talbot","sequence":"additional","affiliation":[{"name":"University of Miami Miller School of Medicine, Department of Microbiology and Immunology, Miami, Florida, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0448-3989","authenticated-orcid":false,"given":"Griffin P.","family":"Carter","sequence":"additional","affiliation":[{"name":"University of Miami Miller School of Medicine, Department of Microbiology and Immunology, Miami, Florida, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3692-8199","authenticated-orcid":false,"given":"George P.","family":"Munson","sequence":"additional","affiliation":[{"name":"University of Miami Miller School of Medicine, Department of Microbiology and Immunology, Miami, Florida, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"54368","reference":[{"key":"2026091620501200000_2026.09.11.750658v1.1","doi-asserted-by":"publisher","DOI":"10.1016\/S2214-109X(18)30483-2"},{"key":"2026091620501200000_2026.09.11.750658v1.2","doi-asserted-by":"publisher","DOI":"10.1371\/journal.ppat.1008776"},{"key":"2026091620501200000_2026.09.11.750658v1.3","doi-asserted-by":"publisher","DOI":"10.1128\/iai.58.4.874-878.1990"},{"key":"2026091620501200000_2026.09.11.750658v1.4","doi-asserted-by":"publisher","DOI":"10.1016\/0022-2836(76)90119-4"},{"key":"2026091620501200000_2026.09.11.750658v1.5","doi-asserted-by":"publisher","DOI":"10.1093\/ije\/dyn099"},{"key":"2026091620501200000_2026.09.11.750658v1.6","doi-asserted-by":"publisher","DOI":"10.1016\/j.gene.2006.04.018"},{"key":"2026091620501200000_2026.09.11.750658v1.7","doi-asserted-by":"publisher","DOI":"10.1128\/iai.19.3.883-888.1978"},{"key":"2026091620501200000_2026.09.11.750658v1.8","doi-asserted-by":"publisher","DOI":"10.1128\/IAI.12.3.656-667.1975"},{"key":"2026091620501200000_2026.09.11.750658v1.9","doi-asserted-by":"publisher","DOI":"10.1016\/0264-410X(93)90021-O"},{"key":"2026091620501200000_2026.09.11.750658v1.10","doi-asserted-by":"publisher","DOI":"10.1038\/NRGASTRO.2012.239"},{"key":"2026091620501200000_2026.09.11.750658v1.11","doi-asserted-by":"publisher","DOI":"10.1128\/jb.178.18.5370-5381.1996"},{"key":"2026091620501200000_2026.09.11.750658v1.12","doi-asserted-by":"publisher","DOI":"10.1128\/JB.183.21.6384-6393.2001"},{"key":"2026091620501200000_2026.09.11.750658v1.13","doi-asserted-by":"publisher","DOI":"10.1128\/IAI.00770-08"},{"key":"2026091620501200000_2026.09.11.750658v1.14","doi-asserted-by":"publisher","DOI":"10.7554\/eLife.63762"},{"key":"2026091620501200000_2026.09.11.750658v1.15","doi-asserted-by":"crossref","unstructured":"Keda, G. , Sankaran, K. , Williams, M. , Aldea, M. , Rudd, K. , Kushner, S. , & Wu, H. 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