FEATURES

FAMILY

DESCRIPTION

Also known as PSB_MYCTU, prcB. Component of the proteasome core, a large protease complex with broad specificity involved in protein degradation. The M.tuberculosis proteasome is able to cleave oligopeptides not only after hydrophobic but also after basic, acidic and small neutral residues (PubMed:16468985). In complex with the ATPase Mpa, degrades protein targets conjugated to a prokaryotic ubiquitin-like protein (Pup). Among the identified substrates of the M.tuberculosis proteasome are the pupylated FabD, PanB and Mpa proteins (PubMed:17082771). One function of the proteasome is to contribute to M.tuberculosis ability to resist killing by host macrophages, since the core proteasome is essential for persistence of the pathogen during the chronic phase of infection in mice (PubMed:18059281). Likely functions to recycle amino acids under nutrient starvation, thereby enabling the cell to maintain basal metabolic activities (PubMed:20711362) (By similarity). The mechanism of protection against bactericidal chemistries of the host's immune response probably involves the degradation of proteins that are irreversibly oxidized, nitrated, or nitrosated. A proteolysis-independent activity of the proteasome core is required for optimal growth of M.tuberculosis in mouse lungs and for RNI resistance; in contrast, long-term survival of M.tuberculosis in stationary phase and during starvation in vitro and in the chronic phase of mouse infection required a proteolytically active proteasome (PubMed:20711362). The 20S proteasome core is composed of 14 alpha and 14 beta subunits that assemble into four stacked heptameric rings, resulting in a barrel-shaped structure. The two inner rings, each composed of seven catalytic beta subunits, are sandwiched by two outer rings, each composed of seven alpha subunits. The catalytic chamber with the active sites is on the inside of the barrel. Has a gated structure, the ends of the cylinder being occluded by the N-termini of the alpha-subunits. Is capped by the proteasome-associated ATPase, ARC (Mpa).

EXTERNAL LINKS

prcB

Proteasome subunit beta

prcB

Molecular Synopsis