Family C47

Family

Summary Holotypes Alignment Genomes Literature Architecture

Summary for family C47

Name	Peptidase family C47 (staphopain family)
Family type peptidase	C47.001 - staphopain A (Staphylococcus aureus), MEROPS Accession MER0061229 (peptidase unit: 215-388)
Content of family	Peptidase family C47 contains endopeptidases.
History	Identifier created: MEROPS 3.1 (22 December 1998) Peptidase activity found in the Staphylococcus aureus culture medium dependent on reducing agents was first described by Arvidson (1973). The peptidase was later purified and classified as a papain-like cysteine peptidase (Arvidson et al., 1973) with broad specificity (Bjorklind & Jornvall, 1974).
Catalytic type	Cysteine
Active site residues	Q232 C238 H334 N355
Active site	Cys24 and His120 form the catalytic dyad with Asn141 interacting with His120. Gln18 is involved in the formation of the oxyanion hole.
Activities and specificities	Staphopain A shows a broad specificity on horse liver alcohol dehydrogenase (Bjorklind & Jornvall, 1974). Assay substrates are Z-Phe-Leu-GluNHPhNO₂ and Z-Phe-ArgNHMec, although haemoglobin and casein may also be used. Staphopain B differs from staphopain A in its more restricted specificity.
Inhibitors	Staphopains A and B are inhibited by staphostatins A (I58.001) and B (I57.001) respectively. It is believed that the staphostatins produced by Staphylococcus aureus prevent degradation of the Staphylococcus cytoplasmic proteins by prematurely activated prostaphopains. Other inhibitors include E64 and cystatin A (I25.001), as well as heavy metals and oxidising agents (Potempa & Travis, 2004).
Molecular structure	The structure of staphopain contains two domains. The N-terminal domain contains four alpha-helices whilst the C-terminal domain forms an eight-stranded antiparallel beta-barrel. The active site residues are found in a cleft between the two domains. The fold of staphopain resembles that of papain, despite the lack of sequence similarity (Hofmann et al., 1993).
Clan	CA
Basis of clan assignment	Protein fold of the peptidase unit for members of this family and resembles that of papain, the type example for clan CA.

Distribution of family	Bacteria	details
	Archaea	-
	Protozoa	-
	Fungi	-
	Plants	-
	Animals	-
	Viruses	-

Biological functions	The staphopains are suggested to be important for the survival of Staphylococcus sp. in vivo, and inhibition of staphopain activity inhibits the growth of the bacteria in vitro Potempa & Travis, 2004.
Pharmaceutical and biotech relevance	Genetic characterization of staphopain genes in Staphylococcus aureus suggests that the staphopains have important housekeeping and/or virulence functions, and therefore may constitute a target for the development of therapeutic inhibitors for the treatment of staphylococcal diseases (Golonka et al., 2004).
Reviews	Potempa & Travis (2004)
Statistics for family C47	Sequences:	27
	Identifiers:	4
	Identifiers with PDB entries:	2
Downloadable files	Sequence library (FastA format)
	Sequence alignment (FastA format)
	Phylogenetic tree (Newick format)

Other databases	CATH	3.90.70.10
	INTERPRO	IPR000169
	PFAM	PF05543
	SCOP	54002

Peptidases and Homologues	MEROPS ID	Structure
staphopain A	C47.001	Yes
staphopain B	C47.002	Yes
EcpA peptidase	C47.003	-
staphopain C	C47.004	-
Family C47 non-peptidase homologues	non-peptidase homologue	-
Family C47 unassigned peptidases	unassigned	-