9VNJ

Crystal structure of the transmembrane domain of trimeric autotransporter adhesin AtaA in complex with the N-terminal domain of TpgA

Summary for 9VNJ

• Entry DOI: 10.2210/pdb9vnj/pdb
• Descriptor: Trimeric autotransporter adhesin AtaA, Trimeric autotransporter adhesin- and peptidoglycan-associated protein A, CALCIUM ION, ... (8 entities in total)
• Functional Keywords: outer membrane, acinetobacter, cell adhesion
• Biological source: Acinetobacter sp. Tol 5; More
• Total number of polymer chains: 2
• Total formula weight: 28643.65

Authors

Yoshimoto, S.,Suzuki, A.,Hiroshige, R.,Hori, K. (deposition date: 2025-06-30, release date: 2025-10-08, Last modification date: 2025-10-29)

Primary citation

Yoshimoto, S.,Sasahara, J.,Suzuki, A.,Kanie, J.,Koiwai, K.,Lupas, A.N.,Hori, K.
Insights into the complex formation of a trimeric autotransporter adhesin with a peptidoglycan-binding periplasmic protein.
Cell Surf, 14:100155-100155, 2025

PubMed Abstract: 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 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.

PubMed: 41103730
DOI: 10.1016/j.tcsw.2025.100155

Experimental method

X-RAY DIFFRACTION (2.6 Å)