3A5I

Structure of the cytoplasmic domain of FlhA

Summary for 3A5I

• Entry DOI: 10.2210/pdb3a5i/pdb
• Descriptor: Flagellar biosynthesis protein flhA (1 entity in total)
• Functional Keywords: four domains, thioredoxin-like fold, bacterial flagellum biogenesis, bacterial flagellum protein export, cell inner membrane, cell membrane, membrane, protein transport, transmembrane, transport
• Biological source: Salmonella typhimurium
• Cellular location: Cell inner membrane; Multi-pass membrane protein: P40729
• Total number of polymer chains: 2
• Total formula weight: 86516.70

Authors

Imada, K.,Saijo-Hamano, Y.,Shimada, M.,Namba, K. (deposition date: 2009-08-07, release date: 2010-03-09, Last modification date: 2024-03-13)

Primary citation

Saijo-Hamano, Y.,Imada, K.,Minamino, T.,Kihara, M.,Shimada, M.,Kitao, A.,Namba, K.
Structure of the cytoplasmic domain of FlhA and implication for flagellar type III protein export
Mol.Microbiol., 76:260-268, 2010

PubMed Abstract: FlhA is the largest integral membrane component of the flagellar type III protein export apparatus of Salmonella and is composed of an N-terminal transmembrane domain (FlhA(TM)) and a C-terminal cytoplasmic domain (FlhA(C)). FlhA(C) is thought to form a platform of the export gate for the soluble components to bind to for efficient delivery of export substrates to the gate. Here, we report a structure of FlhA(C) at 2.8 A resolution. FlhA(C) consists of four subdomains (A(C)D1, A(C)D2, A(C)D3 and A(C)D4) and a linker connecting FlhA(C) to FlhA(TM). The sites of temperature-sensitive (ts) mutations that impair protein export are distributed to all four domains, with half of them at subdomain interfaces. Analyses of the ts mutations and four suppressor mutations to the G368C ts mutation suggested that FlhA(C) changes its conformation for its function. Molecular dynamics simulation demonstrated an open-close motion with a 5-10 ns oscillation in the distance between A(C)D2 and A(C)D4. These results along with further mutation analyses suggest that a dynamic domain motion of FlhA(C) is essential for protein export.

PubMed: 20199603
DOI: 10.1111/j.1365-2958.2010.07097.x

Experimental method

X-RAY DIFFRACTION (2.8 Å)