Stabilizing isopeptide bonds revealed in gram-positive bacterial pilus structure.
Many bacterial pathogens have long, slender pili through which they adhere to host cells. The crystal structure of the major pilin subunit from the Gram-positive human pathogen Streptococcus pyogenes at 2.2 angstroms resolution reveals an extended structure comprising two all-beta domains. The molecules associate in columns through the crystal, with each carboxyl terminus adjacent to a conserved lysine of the next molecule. This lysine forms the isopeptide bonds that link the subunits in native pili, validating the relevance of the crystal assembly. Each subunit contains two lysine-asparagine isopeptide bonds generated by an intramolecular reaction, and we find evidence for similar isopeptide bonds in other cell surface proteins of Gram-positive bacteria. The present structure explains the strength and stability of such Gram-positive pili and could facilitate vaccine development.
Kang
Hae Joo
HJ
Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, Auckland 1010, New Zealand.
Coulibaly
Fasséli
F
Clow
Fiona
F
Proft
Thomas
T
Baker
Edward N
EN
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001216:Asparagine / Q000737:chemistry; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D018360:Crystallography, X-Ray; D036781:Fimbriae Proteins / Q000737:chemistry*; D010861:Fimbriae, Bacterial / Q000737:chemistry* / Q000648:ultrastructure; D006860:Hydrogen Bonding; D008239:Lysine / Q000737:chemistry; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D021122:Protein Subunits / Q000737:chemistry; D013297:Streptococcus pyogenes / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure*
D010455:Peptides; D021122:Protein Subunits; D036781:Fimbriae Proteins; D001216:Asparagine; D008239:Lysine