title: Structure-based functional studies for the cellular recognition and cytolytic mechanism of pneumolysin from Streptococcus pneumoniae.
abstract: Cholesterol-dependent cytolysins (CDCs) contribute to various pathogenesis by Gram-positive bacterial pathogens. Among them, pneumolysin (PLY) produced by Streptococcus pneumoniae is a major contributor to pneumococcal infections. Despite numerous studies of the cytolytic mechanism of PLY, little structural information on its interactions with a specific receptor of the cell membrane is available. We report here the first crystal structures of PLY in an apo-form and in a ternary complex with two mannoses at 2.8Å and 2.5Å resolutions, respectively. Both structures contained one monomer in an asymmetric unit and were comprised of four discontinuous domains, similar to CDC structures reported previously. The ternary complex structure showed that loop 3 and the undecapeptide region in domain 4 might contribute to cellular recognition by binding to mannose, as a component of a specific cell-surface receptor. Moreover, mutational studies and docking simulations for four residues (Leu431, Trp433, Thr459, and Leu460) in domain 4 indicated that Leu431 and Trp433 in the undecapeptide might be involved in the binding of cholesterol, together with the Thr459-Leu460 pair in loop 1. Our results provide structure-based molecular insights into the interaction of PLY with the target cell membrane, including the binding of mannose and cholesterol.
authors.affiliation: Department of Clinical Laboratory Science, College of Health Sciences, Catholic University of Pusan, Busan 609-757, Republic of Korea.
authors.forename: Seong Ah
authors.initials: SA
authors.lastname: Park
authors.affiliation: Department of Clinical Laboratory Science, College of Health Sciences, Catholic University of Pusan, Busan 609-757, Republic of Korea.
authors.forename: Ye Song
authors.initials: YS
authors.lastname: Park
authors.affiliation: Division of Convergence Technology, Biomolecular Function Research Branch, Gyeonggi-do 410-769, Republic of Korea.
authors.forename: Seoung Min
authors.initials: SM
authors.lastname: Bong
authors.affiliation: Department of Clinical Laboratory Science, College of Health Sciences, Catholic University of Pusan, Busan 609-757, Republic of Korea. Electronic address: kslee@cup.ac.kr.
authors.forename: Ki Seog
authors.initials: KS
authors.lastname: Lee
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D002784:Cholesterol / Q000737:chemistry / Q000378:metabolism; D018360:Crystallography, X-Ray; D006461:Hemolysis; D006801:Humans; D008358:Mannose / Q000737:chemistry / Q000378:metabolism; D008958:Models, Molecular; D062105:Molecular Docking Simulation; D009154:Mutation; D017434:Protein Structure, Tertiary; D013301:Streptolysins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D013329:Structure-Activity Relationship
chemical_list: D001426:Bacterial Proteins; D013301:Streptolysins; C032290:plY protein, Streptococcus pneumoniae; D002784:Cholesterol; D008358:Mannose
keywords: Cellular recognition; Cholesterol-dependent cytolysin; Molecular docking; Pneumolysin; X-ray structure