Succinate dehydrogenase cytochrome b558 subunit, Firmicute (IPR016002)

Short name: Succ_DH_cyt_b558_Firmicute

Overlapping homologous superfamilies

Family relationships


This family contains succinate dehydrogenase (also known as succinate:quinone oxidoreductase, SQR) subunit C of Bacillus subtilis, designated cytochrome b-558, and related sequences that include a fumarate reductase subunit C. This family is only weakly similar to the main group of succinate dehydrogenase cytochrome b subunits described by IPR000701, so that some members score above the gathering threshold and some do not [PMID: 3086287].

SQR catalyzes the oxidation of succinate to fumarate coupled to the reduction of quinone to quinol. Bacillus subtilis SQR reduces low potential quinones such as menaquinone [PMID: 9799121]. SQR is part of the citric acid cycle and the aerobic respiratory chain. SQR is composed of a flavoprotein catalytic subunit, an iron-sulfur protein and one or two hydrophobic transmembrane subunits. Members of this entry are classified as Type B as they contain one transmembrane subunit and two heme groups [PMID: 1324713]. The heme and quinone binding sites reside on the cytochrome b558 subunit [PMID: 2120540, PMID: 2176107]. The structural arrangement allows efficient electron transfer between the catalytic subunit, through iron-sulfur centres, and the transmembrane subunit containing the electron acceptor (quinone). The reversible reduction of quinone is an essential feature of respiration, allowing transfer of electrons between respiratory complexes [PMID: 15078221, PMID: 12788489, PMID: 11004459, PMID: 11803013].

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.