Shogo Yoshimoto , Jun Sasahara , Atsuo Suzuki , Junichi Kanie , Kotaro Koiwai , Andrei N. Lupas , Katsutoshi Hori
{"title":"三聚体自体转运体黏附素与肽聚糖结合的质周蛋白复合物的形成","authors":"Shogo Yoshimoto , Jun Sasahara , Atsuo Suzuki , Junichi Kanie , Kotaro Koiwai , Andrei N. Lupas , Katsutoshi Hori","doi":"10.1016/j.tcsw.2025.100155","DOIUrl":null,"url":null,"abstract":"<div><div>Trimeric autotransporter adhesins (TAAs) are outer membrane (OM) proteins that are widely distributed in gram-negative bacteria and are involved primarily in adhesion to biotic and abiotic surfaces, cell agglutination, and biofilm formation. TAAs consist of a passenger domain, which is secreted onto the cell surface, and a transmembrane domain, which forms a pore in the OM to secrete and anchor the passenger domain. Because the interactions between TAAs and chaperones or dedicated auxiliary proteins during secretion are short-lived, TAAs are thought to reside on the OM without forming complexes with other proteins after secretion. In this study, we aimed to clarify the interactions between an <em>Acinetobacter</em> TAA, AtaA, and a peptidoglycan (PG)-binding periplasmic protein, TpgA. Pull-down assays using recombinant proteins identified the interacting domains. X-ray crystallography at 2.6 Å resolution revealed an A3B3 heterohexameric complex structure composed of the N-terminal domain of TpgA and the transmembrane domain of AtaA. TpgA-N consists of two short α helices and three antiparallel β strands, yielding an ααβββ topology similar to BamE. However, the regions corresponding to BamE interfaces with BamA and BamD differ in TpgA-N. All-atom molecular dynamics simulations and mutational assays revealed that both electrostatic and hydrophobic interactions contribute to stable complex formation. Bioinformatic analyses indicate that the TAA-TpgA complex occurs in a wide range of species. These findings will contribute to a better understanding of TAAs and the cell envelope.</div></div>","PeriodicalId":36539,"journal":{"name":"Cell Surface","volume":"14 ","pages":"Article 100155"},"PeriodicalIF":6.2000,"publicationDate":"2025-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Insights into the complex formation of a trimeric autotransporter adhesin with a peptidoglycan-binding periplasmic protein\",\"authors\":\"Shogo Yoshimoto , Jun Sasahara , Atsuo Suzuki , Junichi Kanie , Kotaro Koiwai , Andrei N. Lupas , Katsutoshi Hori\",\"doi\":\"10.1016/j.tcsw.2025.100155\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><div>Trimeric autotransporter adhesins (TAAs) are outer membrane (OM) proteins that are widely distributed in gram-negative bacteria and are involved primarily in adhesion to biotic and abiotic surfaces, cell agglutination, and biofilm formation. TAAs consist of a passenger domain, which is secreted onto the cell surface, and a transmembrane domain, which forms a pore in the OM to secrete and anchor the passenger domain. Because the interactions between TAAs and chaperones or dedicated auxiliary proteins during secretion are short-lived, TAAs are thought to reside on the OM without forming complexes with other proteins after secretion. In this study, we aimed to clarify the interactions between an <em>Acinetobacter</em> TAA, AtaA, and a peptidoglycan (PG)-binding periplasmic protein, TpgA. Pull-down assays using recombinant proteins identified the interacting domains. X-ray crystallography at 2.6 Å resolution revealed an A3B3 heterohexameric complex structure composed of the N-terminal domain of TpgA and the transmembrane domain of AtaA. TpgA-N consists of two short α helices and three antiparallel β strands, yielding an ααβββ topology similar to BamE. However, the regions corresponding to BamE interfaces with BamA and BamD differ in TpgA-N. All-atom molecular dynamics simulations and mutational assays revealed that both electrostatic and hydrophobic interactions contribute to stable complex formation. Bioinformatic analyses indicate that the TAA-TpgA complex occurs in a wide range of species. These findings will contribute to a better understanding of TAAs and the cell envelope.</div></div>\",\"PeriodicalId\":36539,\"journal\":{\"name\":\"Cell Surface\",\"volume\":\"14 \",\"pages\":\"Article 100155\"},\"PeriodicalIF\":6.2000,\"publicationDate\":\"2025-09-29\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Cell Surface\",\"FirstCategoryId\":\"1085\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S2468233025000155\",\"RegionNum\":0,\"RegionCategory\":null,\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"Immunology and Microbiology\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Cell Surface","FirstCategoryId":"1085","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S2468233025000155","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"Immunology and Microbiology","Score":null,"Total":0}
Insights into the complex formation of a trimeric autotransporter adhesin with a peptidoglycan-binding periplasmic protein
Trimeric autotransporter adhesins (TAAs) are outer membrane (OM) proteins that are widely distributed in gram-negative bacteria and are involved primarily in adhesion to biotic and abiotic surfaces, cell agglutination, and biofilm formation. TAAs consist of a passenger domain, which is secreted onto the cell surface, and a transmembrane domain, which forms a pore in the OM to secrete and anchor the passenger domain. Because the interactions between TAAs and chaperones or dedicated auxiliary proteins during secretion are short-lived, TAAs are thought to reside on the OM without forming complexes with other proteins after secretion. In this study, we aimed to clarify the interactions between an Acinetobacter TAA, AtaA, and a peptidoglycan (PG)-binding periplasmic protein, TpgA. Pull-down assays using recombinant proteins identified the interacting domains. X-ray crystallography at 2.6 Å resolution revealed an A3B3 heterohexameric complex structure composed of the N-terminal domain of TpgA and the transmembrane domain of AtaA. TpgA-N consists of two short α helices and three antiparallel β strands, yielding an ααβββ topology similar to BamE. However, the regions corresponding to BamE interfaces with BamA and BamD differ in TpgA-N. All-atom molecular dynamics simulations and mutational assays revealed that both electrostatic and hydrophobic interactions contribute to stable complex formation. Bioinformatic analyses indicate that the TAA-TpgA complex occurs in a wide range of species. These findings will contribute to a better understanding of TAAs and the cell envelope.