Reviewed, UniProtKB/Swiss-Prot Q00471 (CYB6_CHLRE)

Names and origin

Protein names

Recommended name:
    Cytochrome b6

Gene names

Name:

petB

Encoded on

Plastid; Chloroplast

Organism

Chlamydomonas reinhardtii

Taxonomic identifier

3055 [NCBI]

Taxonomic lineage

Eukaryota › Viridiplantae › Chlorophyta › Chlorophyceae › Chlamydomonadales › Chlamydomonadaceae › Chlamydomonas

Protein attributes

Sequence length	215 AA.
Sequence status	Complete.
Sequence processing	The displayed sequence is not processed.
Protein existence	Evidence at protein level.

General annotation (Comments)

Function	Component of the cytochrome b6-f complex, which mediates electron transfer between photosystem II (PSII) and photosystem I (PSI), cyclic electron flow around PSI, and state transitions. HAMAP MF_00633
Cofactor	Binds 2 heme groups. One heme group is bound covalently by a single cysteine link, the other one non-covalently. Ref.7
Subunit structure	The 4 large subunits of the cytochrome b6-f complex are cytochrome b6, subunit IV (17 kDa polypeptide, petD), cytochrome f and the Rieske protein, while the 4 small subunits are petG, petL, petM and petN. The complex functions as a dimer. HAMAP MF_00633
Subcellular location	Plastid › chloroplast thylakoid membrane; Multi-pass membrane protein. HAMAP MF_00633
Post-translational modification	The N-terminus is blocked. HAMAP MF_00633
Miscellaneous	Creation by mutagenesis of a Pro residue at position 204 (a codon that is known to be RNA edited to a Leu codon in tobacco and maize) leads to assembly defective mutants, indicating that the Leu-204 is essential for proper assembly of the cytochrome b6-f complex. This is probably due to lack of assembly of apocytochrome b6 with one of its heme groups. HAMAP MF_00633 Heme 1 (or BH or b566) is high-potential and absorbs at about 566 nm, and heme 2 (or BL or b562) is low-potential and absorbs at about 562 nm By similarity.
Sequence similarities	Belongs to the cytochrome b family. PetB subfamily.

Ontologies

Keywords
Biological process	Electron transport Photosynthesis Transport
Cellular component	Chloroplast Membrane Plastid Thylakoid
Domain	Transmembrane
Ligand	Heme Iron Metal-binding
Technical term	3D-structure
Gene Ontology (GO)
Biological process	photosynthesis Inferred from electronic annotation. Source: HAMAP respiratory electron transport chain Inferred from electronic annotation. Source: InterPro transport Inferred from electronic annotation. Source: UniProtKB-KW
Cellular component	chloroplast thylakoid membrane Inferred from electronic annotation. Source: UniProtKB-SubCell integral to membrane Inferred from electronic annotation. Source: UniProtKB-KW
Molecular function	electron transporter, transferring electrons within cytochrome b6/f complex of photosystem II activity Inferred from electronic annotation. Source: HAMAP iron ion binding Inferred from electronic annotation. Source: UniProtKB-KW oxidoreductase activity Inferred from electronic annotation. Source: InterPro
Complete GO annotation...

Sequence annotation (Features)

Feature key

Position(s)

Length

Description

Graphical view

Feature identifier

Molecule processing

Chain

1 – 215

215

Cytochrome b6 HAMAP MF_00633

PRO_0000061787

Regions

Transmembrane

32 – 52

21

Potential

Transmembrane

90 – 110

21

Potential

Transmembrane

116 – 136

21

Potential

Transmembrane

186 – 206

21

Potential

Sites

Metal binding

86

1

Iron (heme 2 axial ligand) HAMAP MF_00633

Metal binding

100

1

Iron (heme 1 axial ligand) HAMAP MF_00633

Metal binding

187

1

Iron (heme 2 axial ligand) HAMAP MF_00633

Metal binding

202

1

Iron (heme 1 axial ligand) HAMAP MF_00633

Binding site

35

1

Heme 1 (covalent; via 1 link) HAMAP MF_00633

Experimental info

Mutagenesis

204

1

L → P: Leads to defective cytochrome b6-f complex assembly, probably due to lack of heme assembly. Ref.6

Secondary structure

1

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

215

Helix Strand Turn

Details...

Helix

5 – 12

8

Helix

14 – 23

10

Helix

33 – 35

3

Helix

36 – 54

19

Turn

55 – 57

3

Turn

62 – 64

3

Helix

65 – 74

10

Helix

79 – 105

27

Turn

106 – 110

5

Beta strand

111 – 113

3

Helix

115 – 137

23

Helix

142 – 153

12

Helix

154 – 157

4

Helix

161 – 170

10

Beta strand

172 – 176

5

Helix

177 – 188

12

Helix

190 – 209

20

Sequences

	Sequence		Length	Mass (Da)
	Q00471-1 [UniParc]. Last modified December 1, 1992. Version 1. Checksum: E025FB9ED2ED78B4	FASTA	215	24,165
	10 20 30 40 50 60 MSKVYDWFEE RLEIQAIADD ITSKYVPPHV NIFYCIGGIT FTCFLVQVAT GFAMTFYYRP 70 80 90 100 110 120 TVAEAFASVQ YIMTDVNFGW LIRSIHRWSA SMMVLMMVLH VFRVYLTGGF KRPRELTWVT 130 140 150 160 170 180 GVIMAVCTVS FGVTGYSLPW DQVGYWAVKI VTGVPDAIPG VGGFIVELLR GGVGVGQATL 190 200 210 TRFYSLHTFV LPLLTAVFML MHFLMIRKQG ISGPL

References

	« Hide 'large scale' referencesShow 'large scale' references »
[1]	"Nucleotide sequences of the continuous and separated petA, petB and petD chloroplast genes in Chlamydomonas reinhardtii." Bueschlen S., Choquet Y., Kuras R., Wollman F.A. FEBS Lett. 284:257-262(1991) [PubMed: 2060646] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [GENOMIC DNA]. Strain: 137c / CC-125.
[2]	"Nucleotide sequence of the frxC, petB and trnL genes in the chloroplast genome of Chlamydomonas reinhardtii." Huang C., Liu X.-Q. Plant Mol. Biol. 18:985-988(1992) [PubMed: 1581576] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [GENOMIC DNA].
[3]	"Nucleotide diversity in the chloroplast genome of Chlamydomonas reinhardtii." United States Department of Energy Joint Genome Institute Smith D.R. Submitted (OCT-2008) to the EMBL/GenBank/DDBJ databases Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA]. Strain: CC-503.
[4]	"The Chlamydomonas reinhardtii plastid chromosome: islands of genes in a sea of repeats." Maul J.E., Lilly J.W., Cui L., dePamphilis C.W., Miller W., Harris E.H., Stern D.B. Plant Cell 14:2659-2679(2002) [PubMed: 12417694] [Abstract] Cited for: IDENTIFICATION, COMPLETE PLASTID GENOME.
[5]	"Purification and characterization of the cytochrome b6 f complex from Chlamydomonas reinhardtii." Pierre Y., Breyton C., Kramer D., Popot J.-L. J. Biol. Chem. 270:29342-29349(1995) [PubMed: 7493968] [Abstract] Cited for: CHARACTERIZATION. Strain: WT12.
[6]	"Mutations of cytochrome b6 in Chlamydomonas reinhardtii disclose the functional significance for a proline to leucine conversion by petB editing in maize and tobacco." Zito F., Kuras R., Choquet Y., Koessel H., Wollman F.-A. Plant Mol. Biol. 33:79-86(1997) [PubMed: 9037161] [Abstract] Cited for: MUTAGENESIS OF LEU-204. Strain: 137c / CC-125.
[7]	"Biochemical and spectroscopic characterization of the covalent binding of heme to cytochrome b6." de Vitry C., Desbois A., Redeker V., Zito F., Wollman F.A. Biochemistry 43:3956-3968(2004) [PubMed: 15049703] [Abstract] Cited for: HEME-BINDING.
[8]	"An atypical haem in the cytochrome b(6)f complex." Stroebel D., Choquet Y., Popot J.-L., Picot D. Nature 426:413-418(2003) [PubMed: 14647374] [Abstract] Cited for: X-RAY CRYSTALLOGRAPHY (3.1 ANGSTROMS).

Cross-references

Sequence databases

EMBLGenBankDDBJ

X62905 Genomic DNA. Translation: CAA44690.1.
X72918 Genomic DNA. Translation: CAA51423.1.
FJ423446 Genomic DNA. Translation: ACJ50098.1.
BK000554 Genomic DNA. Translation: DAA00911.1.

PIR

S21253.

RefSeq

NP_958365.1.

3D structure databases

PDBPDBe

Entry	Method	Resolution (Å)	Chain	Positions	PDBsum
1Q90	X-ray	3.10	B	1-215	[»]

ModBase

Search...

Proteomic databases

PRIDE

Q00471.

Genome annotation databases

GeneID

2717017.

KEGG

cre:ChreCp008.

Family and domain databases

HAMAP

MF_00633.
[Tree]

InterPro

IPR016175. Cyt_b/b6.
IPR005797. Cyt_b/b6_N.
[Graphical view]

Gene3D

G3DSA:1.20.810.10. Cytochrome_b/b6. 1 hit.

PANTHER

PTHR19271. Cytochrome_b/b6. 1 hit.

Pfam

PF00033. Cytochrom_B_N. 1 hit.
[Graphical view]

PROSITE

PS51002. CYTB_NTER. 1 hit.
[Graphical view]

ProtoNet

Search...

Entry information

Entry name

CYB6_CHLRE

Accession

Primary (citable) accession number: Q00471
Secondary accession number(s): B7U1F1

Entry history

Integrated into UniProtKB/Swiss-Prot:	December 1, 1992
Last sequence update:	December 1, 1992
Last modified:	June 16, 2009
This is version 75 of the entry and version 1 of the sequence. [Complete history]

Entry status

Reviewed (UniProtKB/Swiss-Prot)

Annotation project

HAMAP (High-quality Automated and Manual Annotation of microbial Proteomes)