Holocytochrome c-type synthase (HCCS)

Holocytochrome c-type synthase (HCCS) is an enzyme localized to the inner mitochondrial membrane and is responsible for catalyzing the covalent attachment of heme to apocytochrome c, producing mature holocytochrome c[1][3][6]. This reaction is critical for mitochondrial electron transport and cell energy production through oxidative phosphorylation[1][3][4]. HCCS guarantees cytochrome c's involvement in electron transfer from complex III to complex IV and regulates apoptosis by enabling cytochrome c maturation[1][3][4]. HCCS deficiency due to gene mutations causes microphthalmia with linear skin defects syndrome (MLS), an X-linked dominant disorder leading to eye, skin, and sometimes systemic developmental defects[1][3][4]. The enzyme acts as the primary component of the cytochrome c biogenesis pathway in eukaryotes and requires conserved residues (e.g., His154) for heme binding and complex formation with apocytochrome c[2][4][5]. Currently, there are no known approved drugs directly targeting HCCS, and its main clinical relevance is in genetic and developmental disease rather than pharmacological modulation.

Other names

CCHLCytochrome c-type heme lyaseCytochrome c heme-lyaseHolocytochrome-c synthetaseMCOPS7LSDMCA1MLS (microphthalmia with linear skin defects)CCHL_HUMANDKFZp779I1858