Ca2+-induced linker transformation leads to a compact and rigid collagen-binding domain of Clostridium histolyticum collagenase.
FEBS J
; 276(13): 3589-601, 2009 Jul.
Article
em En
| MEDLINE
| ID: mdl-19490118
ABSTRACT
Clostridium histolyticum collagenase is responsible for extensive tissue destruction in gas gangrene, and its activity is enhanced by calcium ions. The collagen-binding domain is the minimal segment of the enzyme required for binding to insoluble collagen fibrils and for subsequent collagenolysis. The collagen-binding domain is joined to another binding module by a conserved 14-amino-acid linker. The linker undergoes secondary structural transformation from an alpha-helix to a beta-strand and forms a nonprolyl cis-peptide in the presence of calcium ions. In this study, various biophysical methods were utilized to better understand the structure and functional role of the novel calcium-activated linker. Two Ca(2+) ions bind cooperatively with macroscopic association constants of K(1) = 5.01 x 10(5) m(-1) and K(2) = 2.28 x 10(5) m(-1). The chelation of the second calcium ion is enthalpically unfavorable, which could be a result of isomerization of the nonprolyl cis-peptide. The holo protein is more stable than the apo protein against thermal denaturation (DeltaT(m) approximately 20 degrees C) and chemical denaturation (DeltaDeltaG(H2O) approximately 3 kcal x mol(-1) for urea or guanidine HCl denaturation and Delta20% v/v in 2,2,2-trifluoroethanol). The compact holo collagen-binding domain is more resistant to proteolytic digestion than the apo collagen-binding domain. The orientation of the linker appears to play a crucial role in the stability and dynamics of the collagen-binding domain.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Cálcio
/
Colágeno
/
Estrutura Secundária de Proteína
/
Colagenase Microbiana
Tipo de estudo:
Prognostic_studies
Idioma:
En
Revista:
FEBS J
Assunto da revista:
BIOQUIMICA
Ano de publicação:
2009
Tipo de documento:
Article
País de afiliação:
Estados Unidos