{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,30]],"date-time":"2026-07-30T15:09:00Z","timestamp":1785424140495,"version":"3.56.0"},"reference-count":52,"publisher":"American Society for Microbiology","issue":"9","license":[{"start":{"date-parts":[[2025,9,10]],"date-time":"2025-09-10T00:00:00Z","timestamp":1757462400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"},{"start":{"date-parts":[[2025,9,10]],"date-time":"2025-09-10T00:00:00Z","timestamp":1757462400000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/journals.asm.org\/non-commercial-tdm-license"}],"funder":[{"DOI":"10.13039\/100000060","name":"National Institute of Allergy and Infectious Diseases","doi-asserted-by":"publisher","award":["T32 AI052066"],"award-info":[{"award-number":["T32 AI052066"]}],"id":[{"id":"10.13039\/100000060","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100000060","name":"National Institute of Allergy and Infectious Diseases","doi-asserted-by":"publisher","award":["K22 AI137296"],"award-info":[{"award-number":["K22 AI137296"]}],"id":[{"id":"10.13039\/100000060","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100000057","name":"National Institute of General Medical Sciences","doi-asserted-by":"publisher","award":["R35 GM146923"],"award-info":[{"award-number":["R35 GM146923"]}],"id":[{"id":"10.13039\/100000057","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["journals.asm.org"],"crossmark-restriction":true},"short-container-title":["mBio"],"published-print":{"date-parts":[[2025,9,10]]},"abstract":"<jats:title>ABSTRACT<\/jats:title>\n                  <jats:sec>\n                    <jats:title\/>\n                    <jats:p>\n                      Type 3 secretion systems (T3SSs) enable bacterial virulence by translocating virulence proteins (effectors) into host cells.\n                      <jats:italic toggle=\"yes\">Shigella flexneri<\/jats:italic>\n                      requires T3SS to invade and to spread between cells in the colon. To spread,\n                      <jats:italic toggle=\"yes\">S. flexneri<\/jats:italic>\n                      forms membrane protrusions that push into the adjacent host cell. These protrusions are resolved into double membrane vacuoles (DMVs) that the bacteria quickly escape. The mechanisms required for escape from the DMV are poorly understood, but the T3SS translocon pore protein IpaC is essential. Here, we show IpaC forms a pore that is competent for the translocation of T3SS effectors as bacteria spread between cells. To do so, we used a genetic approach to test mutations of IpaC that disrupt its ability to translocate and to form pores. We show that during spread, IpaC is efficiently inserted into the plasma membrane, the membrane-embedded IpaC forms pore complexes, and the IpaC-dependent pores translocate effectors that are necessary for\n                      <jats:italic toggle=\"yes\">S. flexneri<\/jats:italic>\n                      to escape the DMV. We show that T3SS activation is regulated through a distinct mechanism at spread compared to invasion; activation of T3SS secretion does not require pore formation during spread. We further show that IpaC enables a sequential breakdown of the membranes of the DMV. Thus, we show that a distinct regulation of the T3SS during\n                      <jats:italic toggle=\"yes\">S. flexneri<\/jats:italic>\n                      intercellular spread enables the placement of effectors both around\n                      <jats:italic toggle=\"yes\">S. flexneri<\/jats:italic>\n                      and across membranes of the DMV. Altogether, this study provides new insights into how\n                      <jats:italic toggle=\"yes\">S. flexneri<\/jats:italic>\n                      escapes the DMV.\n                    <\/jats:p>\n                    <jats:sec>\n                      <jats:title>IMPORTANCE<\/jats:title>\n                      <jats:p>\n                        The type 3 secretion system (T3SS) is required for virulence inmany bacterial pathogens that infect humans. The T3SS forms a pore through which virulence proteins are delivered into host cells, enabling bacterial infection. Our work investigates the\n                        <jats:italic toggle=\"yes\">Shigella<\/jats:italic>\n                        translocon pore protein IpaC, which is essential not only for bacteria to invade cells but also for bacteria to spread between cells. The ability to spread between cells is essential for pathogenesis; thus, understanding the mechanisms that enable spread is important for determining how\n                        <jats:italic toggle=\"yes\">S. flexneri<\/jats:italic>\n                        infection causes illness. We show that IpaC delivers virulence factors across the host membrane for\n                        <jats:italic toggle=\"yes\">S. flexneri<\/jats:italic>\n                        to efficiently spread. This study furthers our understanding of the mechanisms involved in T3SS secretion and of translocon pore function during\n                        <jats:italic toggle=\"yes\">S. flexneri<\/jats:italic>\n                        intercellular spread.\n                      <\/jats:p>\n                    <\/jats:sec>\n                  <\/jats:sec>","DOI":"10.1128\/mbio.01674-25","type":"journal-article","created":{"date-parts":[[2025,8,11]],"date-time":"2025-08-11T13:00:37Z","timestamp":1754917237000},"update-policy":"https:\/\/doi.org\/10.1128\/asmj-crossmark-policy-page","source":"Crossref","is-referenced-by-count":1,"title":["A translocation-competent pore is required for\n                    <i>Shigella flexneri<\/i>\n                    to escape from the double membrane vacuole during intercellular spread"],"prefix":"10.1128","volume":"16","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-6181-0830","authenticated-orcid":false,"given":"Julie 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USA"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Anza","family":"Darehshouri","sequence":"additional","affiliation":[{"id":[{"id":"https:\/\/ror.org\/03wmf1y16","id-type":"ROR","asserted-by":"publisher"}],"name":"Department of Cell and Developmental Biology, University of Colorado\u2014Anschutz Medical Campus","place":["Aurora, USA"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4266-9733","authenticated-orcid":true,"given":"Marcia B.","family":"Goldberg","sequence":"additional","affiliation":[{"id":[{"id":"https:\/\/ror.org\/002pd6e78","id-type":"ROR","asserted-by":"publisher"}],"name":"Division of Infectious Diseases, Massachusetts General Hospital","place":["Boston, USA"]},{"name":"Department of Microbiology, Blavatnik Institute, Harvard Medical School","place":["Boston, 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