Protein Family Models

This family consists of various proteins involved in cytochrome c assembly from mitochondria and bacteria; CycK from Rhizobium[3], CcmC from E. coli and Paracoccus denitrificans [2,1] and orf240 from wheat mitochondria [4]. The members of this family are probably integral membrane proteins with six predicted transmembrane helices. It has been proposed that members of this family comprise a membrane component of an ABC (ATP binding cassette) transporter complex. It is also proposed that this transporter is necessary for transport of some component needed for cytochrome c assembly. One member CycK contains a putative heme-binding motif [3], orf240 also contains a putative heme-binding motif and is a proposed ABC transporter with c-type heme as its proposed substrate [4]. However it seems unlikely that all members of this family transport heme nor c-type apocytochromes because CcmC in the putative CcmABC transporter transports neither [1]. CcmF forms a working module with CcmH and CcmI, CcmFHI, and itself is unlikely to bind haem directly [5]. [1]. 9043133. The Paracoccus denitrificans ccmA, B and C genes: cloning and sequencing, and analysis of the potential of their products to form a haem or apo-c-type cytochrome transporter. Page D, Pearce DA, Norris HA, Ferguson SJ;. Microbiology 1997;143:563-576. [2]. 7635817. Escherichia coli genes required for cytochrome c maturation. Thony-Meyer L, Fischer F, Kunzler P, Ritz D, Hennecke H;. J Bacteriol 1995;177:4321-4326. [3]. 7665469. Characterization of the cycHJKL genes involved in cytochrome c biogenesis and symbiotic nitrogen fixation in Rhizobium leguminosarum. Delgado MJ, Yeo. TRUNCATED at 1650 bytes (from Pfam)

Gene:

ccsA

Date:

2024-10-16

This model describes the cyt c biogenesis protein encoded by ccmC in bacteria. It must be noted an arabidopsis, a tritcum and a piscum plant proteins were recognizable in the clade. Quite likely they are of organellar origin. Bacterial c-type cytocromes are located on the periplasmic side of the cytoplasmic membrane. Several gene products encoded in a locus designated as 'ccm' are implicated in the transport and assembly of the functional cytochrome C. This cluster includes genes, ccmA;B;C;D;E;F;G and H. The posttranslational pathway includes the transport of heme moiety, the secretion of the apoprotein and the covalent attachment of the heme with the apoprotein. The proteins ccmA and B represent an ABC transporter; ccmC and D participate in the heme transfer to ccmE, which function as a periplasmic heme chaperone. The presence of ccmF, G and H is suggested to be obligatory for the final functional assembly of cytochrome c.

Gene:

ccmC

Date:

2024-05-30

heme ABC transporter permease such as Escherichia coli heme exporter protein C (CcmC), which is required for the export of heme to the periplasm for the biogenesis of c-type cytochromes

Date:

2023-03-17