Streptococcal hemoprotein receptor

UniProtKB accession:  Q99YA0

Grouped By:  Matching UniProtKB accession

UniProtKB description:  Hemoprotein receptor that plays a central role in the acquisition of host heme, a source of iron during bacterial infection, and is therefore an important virulence factor (PubMed:12595414, PubMed:20807204, PubMed:23076332, PubMed:23993953, PubMed:36693107). Captures host hemoproteins and their iron-containing heme molecules, and transfers the heme to the cell surface heme-binding protein Shp (PubMed:18215300, PubMed:23993953). Plays a pivotal role in iron acquisition and growth under iron-starvation conditions (PubMed:23076332). Uses a cap and release mechanism in which Shr forms a dynamic complex with hemoglobin that enables the gated release of its most labile heme molecule (PubMed:36693107). This mechanism exploits the hemoglobin beta subunit's inherent weaker affinity for heme, allowing S.pyogenes to preferentially capture only heme-saturated forms of hemoglobin that contain iron (PubMed:36693107). In vitro, binds directly to a variety of heme-containing proteins, including hemoglobin, myoglobin, heme albumin and the hemoglobin-haptoglobin complex (PubMed:12595414, PubMed:30301765). It also binds to and acquires heme from methemoglobin, the ferric form of hemoglobin, which is likely to be a physiologically relevant heme source for the hemolytic group A streptococcus (GAS) (PubMed:20807204, PubMed:36693107). Seems to have an inherent ability to reduce the ferric heme present in methemoglobin to ferrous heme and to provide a stable environment for the produced ferrous complex (PubMed:20807204). Does not bind apohemoglobin, apohaptoglobin, fibrinogen or streptavidin, indicating that it specifically recognizes hemoproteins (PubMed:12595414, PubMed:20807204).