title: Molecular analysis of Streptococcus anginosus-derived SagA peptides.
abstract: BACKGROUND
  SagA1 and SagA2 molecules produced from beta-hemolytic Streptococcus anginosus subsp. anginosus are composed of a leader peptide and a propeptide, and their mature form has hemolytic activity as a well-known Streptococcal peptide toxin, streptolysin. The function of these SagA molecules is thought to be dependent on intra-molecular heterocycle formation. In this study, we examined the heterocycle-involved molecular features of SagA1, SagA2, and S. pyogenes SagA (SPySagA), focusing on their heterocycle formation.
  
  
  METHODS
  Molecular models of SagA1, SagA2, and SPySagA were constructed using a molecular modeling technique. Molecular dynamics and molecular mechanic analyses of the modeled SagA molecules were performed to obtain their energy profiles.
  
  
  RESULTS
  Total energy of the modeled SagA1, SagA2, and SPySagA decreased with heterocycle formation, and the border between the leader peptide and propeptide was clearly observed after heterocycle formation.
  
  
  CONCLUSIONS
  The flexibility of SagA molecules was changed by intramolecular heterocycle formation, and their function (e.g. hemolytic activity) seems to be regulated by structural transition with heterocycle formation.
authors: Faculty of Pharmaceutical Sciences, Chiba Institute of Science, Choshi, Chiba, Japan.
authors: Yuki
authors: Y
authors: Kawaguchi
authors: Department of Biological Science and Technology, Life System, Institute of Technology and Science, The University of Tokushima Graduate School, Tokushima, Tokushima, Japan.
authors: Atsushi
authors: A
authors: Tabata
authors: Department of Biological Science and Technology, Life System, Institute of Technology and Science, The University of Tokushima Graduate School, Tokushima, Tokushima, Japan.
authors: Hideaki
authors: H
authors: Nagamune
authors: Faculty of Pharmaceutical Sciences, Chiba Institute of Science, Choshi, Chiba, Japan Graduate School of Pharmaceutical Sciences, Suzuka University of Medical Science Graduate School, Suzuka, Mie, Japan kohkura@suzuka-u.ac.jp.
authors: Kazuto
authors: K
authors: Ohkura
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry*; D006571:Heterocyclic Compounds / Q000737:chemistry; D056004:Molecular Dynamics Simulation; D015394:Molecular Structure; D055672:Static Electricity; D034366:Streptococcus anginosus / Q000737:chemistry*; D013301:Streptolysins / Q000737:chemistry*
chemical_list: D001426:Bacterial Proteins; D006571:Heterocyclic Compounds; D013301:Streptolysins
keywords: Cytolysin; SagA; Streptococcus anginosus; hemolysis; heterocycle formation