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MetaCyc Transporter: cytochrome b6f complex

Species: Synechococcus elongatus PCC 7942

Subunit composition of cytochrome b6f complex = [(PetA)(PetB)(PetN)(PetG)(PetD)(PetM)(PetC)]2
         cytochrome b6f complex monomer = (PetA)(PetB)(PetN)(PetG)(PetD)(PetM)(PetC)
                 cytochrome f = PetA (summary available)
                 cytochrome b6 = PetB (summary available)
                 cytochrome b6-f complex subunit 8 = PetN (summary available)
                 cytochrome b6-f complex subunit 5 = PetG (summary available)
                 Cytochrome b6-f complex subunit 4 = PetD (summary available)
                 Cytochrome b6-f complex subunit 7 = PetM (summary available)
                 cytochrome b6-f complex iron-sulfur subunit = PetC (summary available)

Summary:
The cytochrome b6-f complex connects electron transport between photosystem II (PSII) and photosystem I (PSI) and resides in the thylakoid membranes [Schwenkert07]. In cyanobacteria, it is present in both the thylakoid and cytoplasmic membranes [Schneider01]. Cytochrome b6-f is involved in state transition whereby it can migrate from the appressed region of the thylakoid membrane where PSII is located, to the non-appressed region which contains PSI [Iwai10].

In cyanobacteria the cytochrome b6f complex is an essential part of both the respiratory and the photosynthetic electron transport chains. The complex oxidizes plastoquinol and subsequently transfers electrons to the soluble electron carrier plastocyanin [Cape06].

The complex functions as a dimer of large complexes which are composed of 8 subunits each - 4 large subunits ( cytochrome f, cytochrome b6, cytochrome b6-f complex iron-sulfur subunit and Cytochrome b6-f complex subunit 4) and 4 small subunits ( cytochrome b6-f complex subunit 5, PetL, Cytochrome b6-f complex subunit 7, and cytochrome b6-f complex subunit 8) [Schneider01]. PetL was found to be dispensible in Synechococcus elongatus PCC 7942 and the cyanobacterium Synechocystis sp. PCC 6803 [Schneider07].

Cytochrome b6f complexes have been purified from the cyanobacteria Nostoc sp. PCC 7120 and Mastigocladus laminosus [Baniulis11]. The purified complexes contained stoichiometrically bound chlorophyll a and β-carotene at a ratio of approximately one molecule of each per cytochrome f. They also contained bound lipid and detergent, indicating seven lipid-binding sites per monomer. Addition of pure synthetic lipid to the cyanobacterial complex resulted in rapid formation of large (=0.2 mm) crystals that were used for X-ray diffraction analysis and structure determination| [Baniulis11].

Gene-Reaction Schematic

Gene-Reaction Schematic

Credits:
Created 21-May-2008 by Caspi R, SRI International
Revised 03-Aug-2015 by Caspi R, SRI International


Enzymatic reaction of: plastoquinol-plastocyanin reductase (cytochrome b6f complex)

Inferred from experiment

EC Number: 1.10.9.1

Transport reaction diagram for plastoquinol-plastocyanin reductase

In Pathways: ethylene biosynthesis V (engineered), oxygenic photosynthesis, 1-butanol autotrophic biosynthesis, photosynthesis light reactions


Subunit of cytochrome b6f complex monomer: cytochrome f

Synonyms: PetA

Gene: petA Accession Number: SYNPCC7942_1231 (MetaCyc)

Locations: thylakoid membrane

Sequence Length: 324 AAs

Molecular Weight: 34.454 kD (from nucleotide sequence)


GO Terms:
Cellular Component:
GO:0042651 - thylakoid membrane []

Gene Class: UNCLASSIFIED

Unification Links: Protein Model Portal:Q31NV8, SMR:Q31NV8, UniProt:Q31NV8

Relationship Links: InterPro:IN-FAMILY:IPR002325, InterPro:IN-FAMILY:IPR011054, InterPro:IN-FAMILY:IPR024058, InterPro:IN-FAMILY:IPR024094, Pfam:IN-FAMILY:PF01333, Prints:IN-FAMILY:PR00610, Prosite:IN-FAMILY:PS51010

Summary:
PetA (cytochrome f) is one of the large subunits of the cytochrome b6-f complex, which mediates electron transfer between photosystem II (PSII) and photosystem I (PSI). It covalently binds one heme group.


Subunit of cytochrome b6f complex monomer: cytochrome b6

Synonyms: PetB

Gene: petB Accession Number: SYNPCC7942_2331 (MetaCyc)

Locations: thylakoid membrane

Sequence Length: 215 AAs

Molecular Weight: 24.357 kD (from nucleotide sequence)


GO Terms:
Cellular Component:
GO:0042651 - thylakoid membrane []

Gene Class: UNCLASSIFIED

Unification Links: Protein Model Portal:Q54711, SMR:Q54711, UniProt:Q54711

Relationship Links: InterPro:IN-FAMILY:IPR005797, InterPro:IN-FAMILY:IPR016174, InterPro:IN-FAMILY:IPR023530, InterPro:IN-FAMILY:IPR027387, Panther:IN-FAMILY:PTHR19271:SF0, Pfam:IN-FAMILY:PF13631, Prosite:IN-FAMILY:PS51002

Summary:
PetB is one the large subunits of the cytochrome b6-f complex, which mediates electron transfer between photosystem II (PSII) and photosystem I (PSI). It binds 2 heme groups.


Subunit of cytochrome b6f complex monomer: cytochrome b6-f complex subunit 8

Synonyms: PetN, cytochrome b6-f complex subunit VIII, Cytochrome b6-f complex subunit petN

Gene: petN Accession Number: SYNPCC7942_0475 (MetaCyc)

Locations: thylakoid membrane

Sequence Length: 31 AAs

Molecular Weight: 3.67 kD (from nucleotide sequence)


GO Terms:
Cellular Component:
GO:0042651 - thylakoid membrane []

Gene Class: UNCLASSIFIED

Unification Links: Protein Model Portal:Q31R12, SMR:Q31R12, UniProt:Q31R12

Relationship Links: InterPro:IN-FAMILY:IPR005497, Pfam:IN-FAMILY:PF03742

Summary:
PetN is one of the small subunits of the cytochrome b6-f complex, which mediates electron transfer between photosystem II (PSII) and photosystem I (PSI).


Subunit of cytochrome b6f complex monomer: cytochrome b6-f complex subunit 5

Synonyms: PetG, Cytochrome b6-f complex subunit V, Cytochrome b6-f complex subunit petG

Gene: petG Accession Number: SYNPCC7942_1479 (MetaCyc)

Locations: thylakoid membrane

Sequence Length: 37 AAs

Molecular Weight: 3.991 kD (from nucleotide sequence)


GO Terms:
Cellular Component:
GO:0042651 - thylakoid membrane []

Gene Class: UNCLASSIFIED

Unification Links: Protein Model Portal:Q9Z3G1, SMR:Q9Z3G1, UniProt:Q9Z3G1

Relationship Links: InterPro:IN-FAMILY:IPR003683, Pfam:IN-FAMILY:PF02529

Summary:
PetG is one the small subunits the cytochrome b6-f complex, which mediates electron transfer between photosystem II (PSII) and photosystem I (PSI). It is required for either the stability or assembly of the cytochrome b6-f complex.


Subunit of cytochrome b6f complex monomer: Cytochrome b6-f complex subunit 4

Synonyms: PetD

Gene: petD Accession Number: SYNPCC7942_2332 (MetaCyc)

Locations: thylakoid membrane

Sequence Length: 160 AAs

Molecular Weight: 17.623 kD (from nucleotide sequence)


GO Terms:
Cellular Component:
GO:0042651 - thylakoid membrane []

Gene Class: UNCLASSIFIED

Unification Links: Protein Model Portal:Q54710, SMR:Q54710, UniProt:Q54710

Relationship Links: InterPro:IN-FAMILY:IPR005798, InterPro:IN-FAMILY:IPR005870, Panther:IN-FAMILY:PTHR19271:SF0, Pfam:IN-FAMILY:PF00032, Prosite:IN-FAMILY:PS51003

Summary:
PetD is one of the four large subunits of the cytochrome b6-f complex, which mediates electron transfer between photosystem II (PSII) and photosystem I (PSI).


Subunit of cytochrome b6f complex monomer: Cytochrome b6-f complex subunit 7

Synonyms: PetM, cytochrome b6-f complex subunit PetM, Cytochrome b6-f complex subunit VII

Gene: petM Accession Number: SYNPCC7942_2426 (MetaCyc)

Locations: thylakoid membrane

Sequence Length: 37 AAs

Molecular Weight: 3.877 kD (from nucleotide sequence)


GO Terms:
Cellular Component:
GO:0042651 - thylakoid membrane []

Gene Class: UNCLASSIFIED

Unification Links: UniProt:Q31KG3

Relationship Links: InterPro:IN-FAMILY:IPR012595, Pfam:IN-FAMILY:PF08041

Summary:
PetM appears to be a nonessential component for cytochrome b6-f complex activity, but may instead be involved in cytochrome b6-f complex mediated regulatory processes [Schneider01].


Subunit of cytochrome b6f complex monomer: cytochrome b6-f complex iron-sulfur subunit

Synonyms: PetC, plastohydroquinone:plastocyanin oxidoreductase iron-sulfur protein

Gene: petC Accession Number: SYNPCC7942_1232 (MetaCyc)

Locations: thylakoid membrane

Sequence Length: 179 AAs

Molecular Weight: 18.834 kD (from nucleotide sequence)


GO Terms:
Cellular Component:
GO:0042651 - thylakoid membrane []

Gene Class: UNCLASSIFIED

Unification Links: Protein Model Portal:Q31NV7, SMR:Q31NV7, UniProt:Q31NV7

Relationship Links: InterPro:IN-FAMILY:IPR005805, InterPro:IN-FAMILY:IPR014349, InterPro:IN-FAMILY:IPR014909, InterPro:IN-FAMILY:IPR017941, InterPro:IN-FAMILY:IPR023960, Panther:IN-FAMILY:PTHR10134, Pfam:IN-FAMILY:PF00355, Pfam:IN-FAMILY:PF08802, Prints:IN-FAMILY:PR00162, Prosite:IN-FAMILY:PS51296

Summary:
PetC is one of the large subunits of the cytochrome b6-f complex, which mediates electron transfer between photosystem II (PSII) and photosystem I (PSI). Also called Rieske protein, it is a high potential [2Fe-2S] protein with one Rieske domain.


References

Baniulis11: Baniulis D, Zhang H, Zakharova T, Hasan SS, Cramer WA (2011). "Purification and crystallization of the cyanobacterial cytochrome b6f complex." Methods Mol Biol 684;65-77. PMID: 20960122

Cape06: Cape JL, Bowman MK, Kramer DM (2006). "Understanding the cytochrome bc complexes by what they don't do. The Q-cycle at 30." Trends Plant Sci 11(1);46-55. PMID: 16352458

Iwai10: Iwai M, Takizawa K, Tokutsu R, Okamuro A, Takahashi Y, Minagawa J (2010). "Isolation of the elusive supercomplex that drives cyclic electron flow in photosynthesis." Nature 464(7292);1210-3. PMID: 20364124

Schneider01: Schneider D, Berry S, Rich P, Seidler A, Rogner M (2001). "A regulatory role of the PetM subunit in a cyanobacterial cytochrome b6f complex." J Biol Chem 276(20);16780-5. PMID: 11278512

Schneider07: Schneider D, Volkmer T, Rogner M (2007). "PetG and PetN, but not PetL, are essential subunits of the cytochrome b6f complex from Synechocystis PCC 6803." Res Microbiol 158(1);45-50. PMID: 17224258

Schwenkert07: Schwenkert S, Legen J, Takami T, Shikanai T, Herrmann RG, Meurer J (2007). "Role of the low-molecular-weight subunits PetL, PetG, and PetN in assembly, stability, and dimerization of the cytochrome b6f complex in tobacco." Plant Physiol 144(4);1924-35. PMID: 17556510


Report Errors or Provide Feedback
Please cite the following article in publications resulting from the use of MetaCyc: Caspi et al, Nucleic Acids Research 42:D459-D471 2014
Page generated by Pathway Tools version 19.5 (software by SRI International) on Wed Jan 2, 2002, biocyc12.