The Bacterial Flagellar Cap as the Rotary Promoter of Flagellin Self-Assembly

• Published in: Science (American Association for the Advancement of Science) Vol. 290; no. 5499; pp. 2148 - 2152
• Main Authors: Yonekura, Koji, Maki, Saori, Morgan, David Gene, DeRosier, David J., Vonderviszt, Ferenc, Imada, Katsumi, Namba, Keiichi
• Format: Journal Article
• Language: English
• Published: Washington, DC American Society for the Advancement of Science 15.12.2000; American Association for the Advancement of Science; The American Association for the Advancement of Science
• Subjects: Analysis; Bacteria; Bacteria - metabolism; Bacteria - ultrastructure; Bacterial Proteins - chemistry; Bacterial Proteins - metabolism; Bacteriology; Biochemistry; Biogenesis of cell structures, supramolecular organization; Biological and medical sciences; Biophysics; Biotechnology industries; Biotechnology industry; cap-filament complex; Cellular biology; Cryoelectron Microscopy; Cytology; Diffusion; Dimerization; Electron microscopy; Electrons; Energy; Flagella; Flagella (Microbiology); Flagella - metabolism; Flagella - ultrastructure; Flagellin - chemistry; Flagellin - metabolism; Fundamental and applied biological sciences. Psychology; Image analysis; Image Processing, Computer-Assisted; Image reconstruction; Legs; Microbiology; Models, Biological; Molecules; Protein Conformation; Protein Folding; Protein Structure, Quaternary; Protein Structure, Secondary; Protein Structure, Tertiary; Proteins; Self assembly; Three dimensional imaging; United States; Japan; Self assembly; Three dimensional structure; Molecular assembly; Cap structure; Flagellum; Flagellin; Bacteria; Cryoelectronic microscopy; Molecular domain; Structure function relationship; Protein
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.290.5499.2148

The growth of the bacterial flagellar filament occurs at its distal end by self-assembly of flagellin transported from the cytoplasm through the narrow central channel. The cap at the growing end is essential for its growth, remaining stably attached while permitting the flagellin insertion. In order to understand the assembly mechanism, we used electron microscopy to study the structures of the cap-filament complex and isolated cap dimer. Five leg-like anchor domains of the pentameric cap flexibly adjusted their conformations to keep just one flagellin binding site open, indicating a cap rotation mechanism to promote the flagellin self-assembly. This represents one of the most dynamic movements in protein structures.