Reviewed, UniProtKB/Swiss-Prot Q9MBA1 (CAO_ARATH)

Names and origin

Protein names

Recommended name:
    Chlorophyllide a oxygenase, chloroplastic
      Short name=Chlorophyll a oxygenase
    EC=1.13.12.14
Alternative name(s):
    Chlorophyll b synthase
      Short name=AtCAO

Gene names

Name:	CAO
Ordered Locus Names:	At1g44446
ORF Names:	T18F15.7

Organism

Arabidopsis thaliana (Mouse-ear cress) [Complete proteome]

Taxonomic identifier

3702 [NCBI]

Taxonomic lineage

Eukaryota › Viridiplantae › Streptophyta › Embryophyta › Tracheophyta › Spermatophyta › Magnoliophyta › eudicotyledons › core eudicotyledons › rosids › eurosids II › Brassicales › Brassicaceae › Arabidopsis

Protein attributes

Sequence length	536 AA.
Sequence status	Complete.
Sequence processing	The displayed sequence is further processed into a mature form.
Protein existence	Evidence at protein level.

General annotation (Comments)

Function	Catalyzes a two-step oxygenase reaction involved in the synthesis of chlorophyll b. Acts specifically on the non-esterified chlorophyllide a and not on chlorophyll a. Ref.3
Catalytic activity	Chlorophyllide a + O2 + NADPH = 7-hydroxychlorophyllide a + H2O + NADP+. 7-hydroxychlorophyllide a + O2 + NADPH = chlorophyllide b + 2 H2O + NADP+.
Subcellular location	Plastid › chloroplast membrane; Peripheral membrane protein. Plastid › chloroplast thylakoid membrane; Peripheral membrane protein. Ref.7 Ref.8
Induction	By light. Probable feedback regulation. Ref.2
Domain	Consists of three domains A, B and C. The C-terminal C domain possesses catalytic function while the N-terminal A domain confers protein instability in response to chlorophyll b accumulation.
Sequence similarities	Contains 1 Rieske domain.

Ontologies

Keywords
Biological process	Chlorophyll biosynthesis
Cellular component	Chloroplast Membrane Plastid
Coding sequence diversity	Alternative splicing
Domain	Coiled coil Transit peptide
Ligand	2Fe-2S Iron Iron-sulfur Metal-binding NADP
Molecular function	Oxidoreductase
Technical term	Complete proteome
Gene Ontology (GO)
Biological process	chlorophyll biosynthetic process Ref.3 Inferred from mutant phenotype. Source: TAIR oxidation reduction Inferred from electronic annotation. Source: UniProtKB-KW
Cellular component	chloroplast inner membrane Inferred from direct assay. Source: TAIR chloroplast thylakoid membrane Inferred from electronic annotation. Source: UniProtKB-SubCell
Molecular function	2 iron, 2 sulfur cluster binding Inferred from electronic annotation. Source: UniProtKB-KW chlorophyllide a oxygenase activity Ref.3 Inferred from direct assay. Source: TAIR electron carrier activity Inferred from electronic annotation. Source: InterPro iron ion binding Inferred from electronic annotation. Source: UniProtKB-KW
Complete GO annotation...

Alternative products

This entry describes 3 isoforms produced by alternative splicing. [Align] [Select]

Isoform 1 (identifier: Q9MBA1-1)

This isoform has been chosen as the 'canonical' sequence. All positional information in this entry refers to it. This is also the sequence that appears in the downloadable versions of the entry.

Isoform 2 (identifier: Q9MBA1-2)

The sequence of this isoform differs from the canonical sequence as follows:
     484-511: LNEDLRLVLGQQERMLNGANIWNLPVAY → KVHHKWIDHLQPSSQSCFLSYRFYISRS
     512-536: Missing.

Note: Derived from EST data. No experimental confirmation available.

Isoform 3 (identifier: Q9MBA1-3)

The sequence of this isoform differs from the canonical sequence as follows:
     384-433: SLVKFLTPTS...GKLEGKSTQQ → RFLLTLITLF...LGSISNRYGI
     434-536: Missing.

Note: Derived from EST data. No experimental confirmation available.

Sequence annotation (Features)

	Feature key	Position(s)	Length	Description	Graphical view	Feature identifier
Molecule processing
	Transit peptide	1 – 36	36	Chloroplast Potential
	Chain	37 – 536	500	Chlorophyllide a oxygenase, chloroplastic		PRO_0000045788
Regions
	Domain	221 – 321	101	Rieske
	Coiled coil	123 – 150	28	Potential
Sites
	Metal binding	262	1	Iron-sulfur (2Fe-2S) By similarity
	Metal binding	264	1	Iron-sulfur (2Fe-2S); via pros nitrogen By similarity
	Metal binding	281	1	Iron-sulfur (2Fe-2S) By similarity
	Metal binding	284	1	Iron-sulfur (2Fe-2S); via pros nitrogen By similarity
	Metal binding	360	1	Iron By similarity
	Metal binding	364	1	Iron By similarity
	Metal binding	367	1	Iron By similarity
	Metal binding	372	1	Iron By similarity
Natural variations
	Alternative sequence	384 – 433	50	SLVKF…KSTQQ → RFLLTLITLFSAKMKLGLSF LFLVLQFGEVFNTYLGSPRI LGSISNRYGI in isoform 3.		VSP_017071
	Alternative sequence	434 – 536	103	Missing in isoform 3.		VSP_017072
	Alternative sequence	484 – 511	28	LNEDL…LPVAY → KVHHKWIDHLQPSSQSCFLS YRFYISRS in isoform 2.		VSP_017073
	Alternative sequence	512 – 536	25	Missing in isoform 2.		VSP_017074
Experimental info
	Mutagenesis	274	1	V → E in chl-2; reduced level of chlorophyll b.
	Mutagenesis	334 – 335	2	SL → VA in chl-3; reduced level of chlorophyll b.
	Mutagenesis	336 – 375	40	Missing in chl-3; absence of chlorophyll b.
	Sequence conflict	115	1	P → R in AAD54323. Ref.2
	Sequence conflict	438	1	L → F in BAA82484. Ref.1
	Sequence conflict	456	1	Y → C in BAA82484. Ref.1

Sequences

	Sequence		Length	Mass (Da)
	Isoform 1 [UniParc]. Last modified October 1, 2000. Version 1. Checksum: E28640DB19F8C3FB	FASTA	536	60,331
	10 20 30 40 50 60 MNAAVFSPSA LSLPISFSKT RSSFLSRKKG VKGEFRVFAV FGDESGLVEK KSQWRPLFDV 70 80 90 100 110 120 EDPRSKAPPY KGKFLDVNQA IEVARFDIQY LDWRARQDLL TIMILHDKVV DVLNPLAREY 130 140 150 160 170 180 KSIGTVKKEL AGLQEELSKA HQQVHISEAR VSTALDKLAH MEELVNDRLL PGRVVTELDK 190 200 210 220 230 240 PSSSTTASAV ELDREKTNTG AKSLNVSGPV PPYSPHLKNF WYPVAFTADL KHDTMVPIEC 250 260 270 280 290 300 FEQPWVIFRG EDGKPGCVRN TCAHRACPLD LGTVNEGRIQ CPYHGWEYST DGECKKMPST 310 320 330 340 350 360 KLLKVKIKSL PCLEQEGMIW IWPGDEPPAP ILPSLQPPSG FLIHAELVMD LPVEHGLLLD 370 380 390 400 410 420 NLLDLAHAPF THTSTFAKGW SVPSLVKFLT PTSGLQGYWD PYPIDMEFKP PCIVLSTIGI 430 440 450 460 470 480 SKPGKLEGKS TQQCATHLHQ LHVCLPSSKN KTRLLYRMSL DFAPILKNLP FMEHLWRHFA 490 500 510 520 530 EQVLNEDLRL VLGQQERMLN GANIWNLPVA YDKLGVRYRL WRNAVDRGDD KLPFSG
	Isoform 2. Checksum: 0F731ED60CC9F6DD	FASTA	511	57,625
	10 20 30 40 50 60 MNAAVFSPSA LSLPISFSKT RSSFLSRKKG VKGEFRVFAV FGDESGLVEK KSQWRPLFDV 70 80 90 100 110 120 EDPRSKAPPY KGKFLDVNQA IEVARFDIQY LDWRARQDLL TIMILHDKVV DVLNPLAREY 130 140 150 160 170 180 KSIGTVKKEL AGLQEELSKA HQQVHISEAR VSTALDKLAH MEELVNDRLL PGRVVTELDK 190 200 210 220 230 240 PSSSTTASAV ELDREKTNTG AKSLNVSGPV PPYSPHLKNF WYPVAFTADL KHDTMVPIEC 250 260 270 280 290 300 FEQPWVIFRG EDGKPGCVRN TCAHRACPLD LGTVNEGRIQ CPYHGWEYST DGECKKMPST 310 320 330 340 350 360 KLLKVKIKSL PCLEQEGMIW IWPGDEPPAP ILPSLQPPSG FLIHAELVMD LPVEHGLLLD 370 380 390 400 410 420 NLLDLAHAPF THTSTFAKGW SVPSLVKFLT PTSGLQGYWD PYPIDMEFKP PCIVLSTIGI 430 440 450 460 470 480 SKPGKLEGKS TQQCATHLHQ LHVCLPSSKN KTRLLYRMSL DFAPILKNLP FMEHLWRHFA 490 500 510 EQVKVHHKWI DHLQPSSQSC FLSYRFYISR S
	Isoform 3. Checksum: 26E6124759110F07	FASTA	433	48,397
	10 20 30 40 50 60 MNAAVFSPSA LSLPISFSKT RSSFLSRKKG VKGEFRVFAV FGDESGLVEK KSQWRPLFDV 70 80 90 100 110 120 EDPRSKAPPY KGKFLDVNQA IEVARFDIQY LDWRARQDLL TIMILHDKVV DVLNPLAREY 130 140 150 160 170 180 KSIGTVKKEL AGLQEELSKA HQQVHISEAR VSTALDKLAH MEELVNDRLL PGRVVTELDK 190 200 210 220 230 240 PSSSTTASAV ELDREKTNTG AKSLNVSGPV PPYSPHLKNF WYPVAFTADL KHDTMVPIEC 250 260 270 280 290 300 FEQPWVIFRG EDGKPGCVRN TCAHRACPLD LGTVNEGRIQ CPYHGWEYST DGECKKMPST 310 320 330 340 350 360 KLLKVKIKSL PCLEQEGMIW IWPGDEPPAP ILPSLQPPSG FLIHAELVMD LPVEHGLLLD 370 380 390 400 410 420 NLLDLAHAPF THTSTFAKGW SVPRFLLTLI TLFSAKMKLG LSFLFLVLQF GEVFNTYLGS 430 PRILGSISNR YGI

References

	« Hide 'large scale' referencesShow 'large scale' references »
[1]	"Chlorophyll b and phycobilins in the common ancestor of cyanobacteria and chloroplasts." Tomitani A., Okada K., Miyashita H., Matthijs H.C.P., Ohno T., Tanaka A. Nature 400:159-162(1999) [PubMed: 10408441] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [MRNA] (ISOFORM 1).
[2]	"The AtCAO gene, encoding chlorophyll a oxygenase, is required for chlorophyll b synthesis in Arabidopsis thaliana." Espineda C.E., Linford A.S., Devine D., Brusslan J.A. Proc. Natl. Acad. Sci. U.S.A. 96:10507-10511(1999) [PubMed: 10468639] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [GENOMIC DNA] (ISOFORM 1), MUTANTS CHL-2 AND CHL-3, INDUCTION. Strain: cv. Columbia.
[3]	"Cloning and functional expression of the gene encoding the key enzyme for chlorophyll b biosynthesis (CAO) from Arabidopsis thaliana." Oster U., Tanaka R., Tanaka A., Ruediger W. Plant J. 21:305-310(2000) [PubMed: 10758481] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [GENOMIC DNA] (ISOFORM 1), FUNCTION.
[4]	"Sequence and analysis of chromosome 1 of the plant Arabidopsis thaliana." Theologis A., Ecker J.R., Palm C.J., Federspiel N.A., Kaul S., White O., Alonso J., Altafi H., Araujo R., Bowman C.L., Brooks S.Y., Buehler E., Chan A., Chao Q., Chen H., Cheuk R.F., Chin C.W., Chung M.K. , Conn L., Conway A.B., Conway A.R., Creasy T.H., Dewar K., Dunn P., Etgu P., Feldblyum T.V., Feng J.-D., Fong B., Fujii C.Y., Gill J.E., Goldsmith A.D., Haas B., Hansen N.F., Hughes B., Huizar L., Hunter J.L., Jenkins J., Johnson-Hopson C., Khan S., Khaykin E., Kim C.J., Koo H.L., Kremenetskaia I., Kurtz D.B., Kwan A., Lam B., Langin-Hooper S., Lee A., Lee J.M., Lenz C.A., Li J.H., Li Y.-P., Lin X., Liu S.X., Liu Z.A., Luros J.S., Maiti R., Marziali A., Militscher J., Miranda M., Nguyen M., Nierman W.C., Osborne B.I., Pai G., Peterson J., Pham P.K., Rizzo M., Rooney T., Rowley D., Sakano H., Salzberg S.L., Schwartz J.R., Shinn P., Southwick A.M., Sun H., Tallon L.J., Tambunga G., Toriumi M.J., Town C.D., Utterback T., Van Aken S., Vaysberg M., Vysotskaia V.S., Walker M., Wu D., Yu G., Fraser C.M., Venter J.C., Davis R.W. Nature 408:816-820(2000) [PubMed: 11130712] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA]. Strain: cv. Columbia.
[5]	"Empirical analysis of transcriptional activity in the Arabidopsis genome." Yamada K., Lim J., Dale J.M., Chen H., Shinn P., Palm C.J., Southwick A.M., Wu H.C., Kim C.J., Nguyen M., Pham P.K., Cheuk R.F., Karlin-Newmann G., Liu S.X., Lam B., Sakano H., Wu T., Yu G. , Miranda M., Quach H.L., Tripp M., Chang C.H., Lee J.M., Toriumi M.J., Chan M.M., Tang C.C., Onodera C.S., Deng J.M., Akiyama K., Ansari Y., Arakawa T., Banh J., Banno F., Bowser L., Brooks S.Y., Carninci P., Chao Q., Choy N., Enju A., Goldsmith A.D., Gurjal M., Hansen N.F., Hayashizaki Y., Johnson-Hopson C., Hsuan V.W., Iida K., Karnes M., Khan S., Koesema E., Ishida J., Jiang P.X., Jones T., Kawai J., Kamiya A., Meyers C., Nakajima M., Narusaka M., Seki M., Sakurai T., Satou M., Tamse R., Vaysberg M., Wallender E.K., Wong C., Yamamura Y., Yuan S., Shinozaki K., Davis R.W., Theologis A., Ecker J.R. Science 302:842-846(2003) [PubMed: 14593172] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE MRNA] (ISOFORM 1). Strain: cv. Columbia.
[6]	"Domain structures of chlorophyllide a oxygenase of green plants and Prochlorothrix hollandica in relation to catalytic functions." Nagata N., Satoh S., Tanaka R., Tanaka A. Planta 218:1019-1025(2004) [PubMed: 14716565] [Abstract] Cited for: CHARACTERIZATION.
[7]	"Synthesis of chlorophyll b: localization of chlorophyllide a oxygenase and discovery of a stable radical in the catalytic subunit." Eggink L.L., LoBrutto R., Brune D.C., Brusslan J., Yamasato A., Tanaka A., Hoober J.K. BMC Plant Biol. 4:5-5(2004) [PubMed: 15086960] [Abstract] Cited for: SUBCELLULAR LOCATION.
[8]	"The N-terminal domain of chlorophyllide a oxygenase confers protein instability in response to chlorophyll b accumulation in Arabidopsis." Yamasato A., Nagata N., Tanaka R., Tanaka A. Plant Cell 17:1585-1597(2005) [PubMed: 15805480] [Abstract] Cited for: CHARACTERIZATION, SUBCELLULAR LOCATION.

Cross-references

Sequence databases
EMBLGenBankDDBJ	AB021316 mRNA. Translation: BAA82484.1. AF177200 Genomic DNA. Translation: AAD54323.1. AB030565 Genomic DNA. Translation: BAA90462.1. AC084807 Genomic DNA. Translation: AAK43487.1. AY128357 mRNA. Translation: AAM91560.1. BT002075 mRNA. Translation: AAN72086.1.
IPI	IPI00519476. IPI00521014. IPI00532566.
PIR	T52458.
RefSeq	NP_175088.1. NP_973969.1. NP_973970.1.
UniGene	At.19047
3D structure databases
ModBase	Search...
Proteomic databases
PRIDE	Q9MBA1.
Genome annotation databases
GeneID	841029.
GenomeReviews	Gene locus AT1G44446 in contig CT485782_GR.
KEGG	ath:AT1G44446.
NMPDR	fig|3702.1.peg.4097.
Organism-specific databases
TAIR	At1g44446.
Phylogenomic databases
OMA	Q9MBA1. NEGRIQC.
Enzyme and pathway databases
BioCyc	MetaCyc:AT1G44446-MON.
BRENDA	1.13.12.14. 302.
Gene expression databases
ArrayExpress	Q9MBA1.
GermOnline	AT1G44446. Arabidopsis thaliana.
Family and domain databases
InterPro	IPR013626. PaO. IPR017941. Rieske_2Fe-2S. [Graphical view]
Gene3D	G3DSA:2.102.10.10. Rieske_reg. 1 hit.
Pfam	PF08417. PaO. 1 hit. PF00355. Rieske. 1 hit. [Graphical view]
PROSITE	PS51296. RIESKE. 1 hit. [Graphical view]
ProtoNet	Search...

Entry information

Entry name

CAO_ARATH

Accession

Primary (citable) accession number: Q9MBA1
Secondary accession number(s): Q3ECX2 , Q3ECX3, Q9SPF2, Q9XJ37

Entry history

Integrated into UniProtKB/Swiss-Prot:	January 24, 2006
Last sequence update:	October 1, 2000
Last modified:	June 16, 2009
This is version 59 of the entry and version 1 of the sequence. [Complete history]

Entry status

Reviewed (UniProtKB/Swiss-Prot)

Annotation project

PPAP (Plant Proteome Annotation Project)