Cytochrome f

Cytochrome f is the largest subunit of cytochrome b6f complex (plastoquinol—plastocyanin reductase; EC 1.10.99.1). In its structure and functions, the cytochrome b6f complex bears extensive analogy to the cytochrome bc1 complex of mitochondria and photosynthetic purple bacteria. Cytochrome f (cyt f) plays a role analogous to that of cytochrome c1, in spite of their different structures.[1]

Apocytochr_F_C
cytochrome f from the b6f complex of Phormidium laminosum
Identifiers
SymbolApocytochr_F_C
PfamPF01333
Pfam clanCL0105
InterProIPR002325
PROSITEPDOC00169
SCOP21ctm / SCOPe / SUPFAM
TCDB3.D.3
OPM superfamily92
OPM protein3h1j
Available protein structures:
Pfam  structures / ECOD  
PDBRCSB PDB; PDBe; PDBj
PDBsumstructure summary

The 3D structure of Brassica rapa (Turnip) cyt f has been determined.[2] The lumen-side segment of cyt f includes two structural domains: a small one above a larger one that, in turn, is on top of the attachment to the membrane domain. The large domain consists of an anti-parallel beta-sandwich and a short haem-binding peptide, which form a three-layer structure. The small domain is inserted between beta-strands F and G of the large domain and is an all-beta domain. The haem nestles between two short helices at the N terminus of cyt f. Within the second helix is the sequence motif for the c-type cytochromes, CxxCH (residues 21–25), which is covalently attached to the haem through thioether bonds to Cys-21 and Cys-24. His-25 is the fifth haem iron ligand. The sixth haem iron ligand is the alpha-amino group of Tyr-1 in the first helix.[2] Cyt f has an internal network of water molecules that may function as a proton wire.[2] The water chain appears to be a conserved feature of cyt f.

References
  1. Prince RC, George GN (June 1995). "Cytochrome f revealed". Trends Biochem. Sci. 20 (6): 217–8. doi:10.1016/S0968-0004(00)89018-0. PMID 7631417.
  2. Martinez SE, Huang D, Ponomarev M, Cramer WA, Smith JL (June 1996). "The heme redox center of chloroplast cytochrome f is linked to a buried five-water chain". Protein Sci. 5 (6): 1081–92. doi:10.1002/pro.5560050610. PMC 2143431. PMID 8762139.

Further reading
This article incorporates text from the public domain Pfam and InterPro: IPR002325
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