Brucella immunogenic BP26 forms a channel-like structure.
An outer membrane protein BP26/OMP28 of Brucella, BP26, is identified as a major immunodominant antigen and widely used as a diagnostic marker and for vaccination against Brucellosis. BP26 belongs to the family of proteins that contains a SIMPL (signaling molecule that associates with the mouse pelle-like kinase) domain, whose structure and function have been unknown. Here, we present the crystal structure of BP26 revealing that 16 BP26 molecules form a novel channel-like assembly as also shown by electron microscopy analysis. Eight BP26 molecules forming a ring structure contain a hole at the center of the octamer, and another octamer interacts with each other to form a channel having a large internal cavity. BP26 is found to be structurally similar to a bacteriophage protein involved in infection, implicating that BP26 might function during Brucella infection. In addition, the BP26 structure suggests that the protein functions as a multimeric channel-like form and provides a canonical model for the SIMPL domains.
Department of Biological Sciences, KI for the BioCentury, KAIST, 335 Gwahangno, Daejeon 305-701, Korea.
Daegeun
D
Kim
Jihye
J
Park
Soo Jin
SJ
Kim
Young-Min
YM
Soh
Ho Min
HM
Kim
Byung-Ha
BH
Oh
Ji-Joon
JJ
Song
D000595:Amino Acid Sequence; D000942:Antigens, Bacterial / Q000737:chemistry / Q000235:genetics / Q000648:ultrastructure; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000648:ultrastructure; D002002:Brucella / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D018360:Crystallography, X-Ray; D007473:Ion Channels / Q000737:chemistry* / Q000235:genetics / Q000648:ultrastructure; D008565:Membrane Proteins / Q000737:chemistry* / Q000235:genetics / Q000648:ultrastructure; D008854:Microscopy, Electron; D008958:Models, Molecular; D008969:Molecular Sequence Data; D055503:Protein Multimerization; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid
D000942:Antigens, Bacterial; C106040:BP26 protein, Brucella; D001426:Bacterial Proteins; D007473:Ion Channels; D008565:Membrane Proteins