Characterization of Staphylococcus aureus EssB, an integral membrane component of the Type VII secretion system: atomic resolution crystal structure of the cytoplasmic segment.
Biochem J
; 449(2): 469-77, 2013 Jan 15.
Article
en En
| MEDLINE
| ID: mdl-23098276
ABSTRACT
The Type VII protein translocation/secretion system, unique to Gram-positive bacteria, is a key virulence determinant in Staphylococcus aureus. We aim to characterize the architecture of this secretion machinery and now describe the present study of S. aureus EssB, a 52 kDa bitopic membrane protein essential for secretion of the ESAT-6 (early secretory antigenic target of 6 kDa) family of proteins, the prototypic substrate of Type VII secretion. Full-length EssB was heterologously expressed in Escherichia coli, solubilized from the bacterial membrane, purified to homogeneity and shown to be dimeric. A C-terminal truncation, EssB∆C, and two soluble fragments termed EssB-N and EssB-C, predicted to occur on either side of the cytoplasmic membrane, have been successfully purified in a recombinant form, characterized and, together with the full-length protein, used in crystallization trials. EssB-N, the 25 kDa N-terminal cytoplasmic fragment, gave well-ordered crystals and we report the structure, determined by SAD (single-wavelength anomalous diffraction) targeting an SeMet (selenomethionine) derivative, refined to atomic (1.05 Å; 1 Å=0.1 nm) resolution. EssB-N is dimeric in solution, but crystallizes as a monomer and displays a fold comprised of two globular domains separated by a cleft. The structure is related to that of serine/threonine protein kinases and the present study identifies that the Type VII secretion system exploits and re-uses a stable modular entity and fold that has evolved to participate in protein-protein interactions in a similar fashion to the catalytically inert pseudokinases.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Contexto en salud:
3_ND
Problema de salud:
3_neglected_diseases
/
3_zoonosis
Asunto principal:
Staphylococcus aureus
/
Proteínas Bacterianas
/
Proteínas de la Membrana
Tipo de estudio:
Prognostic_studies
Idioma:
En
Revista:
Biochem J
Año:
2013
Tipo del documento:
Article
País de afiliación:
Reino Unido