Structure of the competence pilus major pilin ComGC in Streptococcus pneumoniae

• Published in: The Journal of biological chemistry Vol. 292; no. 34; pp. 14134 - 14146
• Main Authors: Muschiol, Sandra, Erlendsson, Simon, Aschtgen, Marie-Stephanie, Oliveira, Vitor, Schmieder, Peter, de Lichtenberg, Casper, Teilum, Kaare, Boesen, Thomas, Akbey, Umit, Henriques-Normark, Birgitta
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 25-08-2017; American Society for Biochemistry and Molecular Biology
• Subjects: Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Cryoelectron Microscopy; Dimerization; Fimbriae Proteins - chemistry; Fimbriae Proteins - genetics; Fimbriae Proteins - metabolism; Fimbriae, Bacterial - metabolism; Fimbriae, Bacterial - ultrastructure; Gene Deletion; horizontal gene transfer; Hydrophobic and Hydrophilic Interactions; Kinetics; Lipid Bilayers - chemistry; Lipid Bilayers - metabolism; major pilin; Medicin och hälsovetenskap; Microbiology; Microscopy, Electron, Transmission; Models, Molecular; nuclear magnetic resonance (NMR); Nuclear Magnetic Resonance, Biomolecular; Operon; Peptide Fragments - chemistry; Peptide Fragments - genetics; Peptide Fragments - metabolism; pneumococci; Protein Conformation; Protein Conformation, alpha-Helical; protein structure; Recombinant Fusion Proteins; Solubility; Streptococcus pneumoniae; Streptococcus pneumoniae - physiology; Streptococcus pneumoniae - ultrastructure; Trans-Activators - genetics; Trans-Activators - metabolism; transformation; type IV pili; Virulence Factors - chemistry; Virulence Factors - genetics; Virulence Factors - metabolism; protein structure; pneumococci; nuclear magnetic resonance (NMR); microbiology; major pilin; transformation; horizontal gene transfer; type IV pili; Streptococcus pneumoniae
• ISSN: 0021-9258; 1083-351X; 1083-351X
• DOI: 10.1074/jbc.M117.787671

Type IV pili are important virulence factors on the surface of many pathogenic bacteria and have been implicated in a wide range of diverse functions, including attachment, twitching motility, biofilm formation, and horizontal gene transfer. The respiratory pathogen Streptococcus pneumoniae deploys type IV pili to take up DNA during transformation. These “competence pili” are composed of the major pilin protein ComGC and exclusively assembled during bacterial competence, but their biogenesis remains unclear. Here, we report the high resolution NMR structure of N-terminal truncated ComGC revealing a highly flexible and structurally divergent type IV pilin. It consists of only three α-helical segments forming a well-defined electronegative cavity and confined electronegative and hydrophobic patches. The structure is particularly flexible between the first and second α-helix with the first helical part exhibiting slightly slower dynamics than the rest of the pilin, suggesting that the first helix is involved in forming the pilus structure core and that parts of helices two and three are primarily surface-exposed. Taken together, our results provide the first structure of a type IV pilin protein involved in the formation of competence-induced pili in Gram-positive bacteria and corroborate the remarkable structural diversity among type IV pilin proteins.