ID   BKT3_HAELA              Reviewed;         320 AA.
AC   Q6J3N5;
DT   07-APR-2021, integrated into UniProtKB/Swiss-Prot.
DT   05-JUL-2004, sequence version 1.
DT   03-AUG-2022, entry version 43.
DE   RecName: Full=Beta-carotene 4-ketolase 3 {ECO:0000303|PubMed:16242201};
DE            Short=HpBKT3 {ECO:0000303|PubMed:21398427};
DE            EC=1.14.99.63 {ECO:0000269|PubMed:16242201, ECO:0000269|PubMed:21398427, ECO:0000269|PubMed:22526507};
GN   Name=BKT3 {ECO:0000303|PubMed:16242201};
OS   Haematococcus lacustris (Green alga) (Haematococcus pluvialis).
OC   Eukaryota; Viridiplantae; Chlorophyta; core chlorophytes; Chlorophyceae;
OC   CS clade; Chlamydomonadales; Haematococcaceae; Haematococcus.
OX   NCBI_TaxID=44745;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [MRNA], FUNCTION, CATALYTIC ACTIVITY, AND INDUCTION BY
RP   SALT STRESS.
RC   STRAIN=NIES-144 / IAM C-392 / MKF-8;
RX   PubMed=16242201; DOI=10.1016/j.jbiotec.2005.09.002;
RA   Huang J.C., Chen F., Sandmann G.;
RT   "Stress-related differential expression of multiple beta-carotene ketolase
RT   genes in the unicellular green alga Haematococcus pluvialis.";
RL   J. Biotechnol. 122:176-185(2006).
RN   [2]
RP   FUNCTION, AND CATALYTIC ACTIVITY.
RX   PubMed=21398427; DOI=10.1093/jxb/err070;
RA   Zhong Y.J., Huang J.C., Liu J., Li Y., Jiang Y., Xu Z.F., Sandmann G.,
RA   Chen F.;
RT   "Functional characterization of various algal carotenoid ketolases reveals
RT   that ketolating zeaxanthin efficiently is essential for high production of
RT   astaxanthin in transgenic Arabidopsis.";
RL   J. Exp. Bot. 62:3659-3669(2011).
RN   [3]
RP   FUNCTION, AND CATALYTIC ACTIVITY.
RX   PubMed=22526507; DOI=10.1007/s00425-012-1654-6;
RA   Huang J., Zhong Y., Sandmann G., Liu J., Chen F.;
RT   "Cloning and selection of carotenoid ketolase genes for the engineering of
RT   high-yield astaxanthin in plants.";
RL   Planta 236:691-699(2012).
CC   -!- FUNCTION: Involved in the biosynthesis of ketocarotenoids which are
CC       powerful anti-oxidative molecules (PubMed:16242201, PubMed:21398427,
CC       PubMed:22526507). Catalyzes the conversion of beta-carotene to
CC       canthaxanthin via echinenone (PubMed:16242201, PubMed:21398427,
CC       PubMed:22526507). {ECO:0000269|PubMed:16242201,
CC       ECO:0000269|PubMed:21398427, ECO:0000269|PubMed:22526507}.
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=2 AH2 + echinenone + 2 O2 = 2 A + canthaxanthin + 3 H2O;
CC         Xref=Rhea:RHEA:55664, ChEBI:CHEBI:3362, ChEBI:CHEBI:4746,
CC         ChEBI:CHEBI:13193, ChEBI:CHEBI:15377, ChEBI:CHEBI:15379,
CC         ChEBI:CHEBI:17499; EC=1.14.99.63;
CC         Evidence={ECO:0000269|PubMed:16242201, ECO:0000269|PubMed:21398427,
CC         ECO:0000269|PubMed:22526507};
CC       PhysiologicalDirection=left-to-right; Xref=Rhea:RHEA:55665;
CC         Evidence={ECO:0000269|PubMed:16242201, ECO:0000269|PubMed:21398427,
CC         ECO:0000269|PubMed:22526507};
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=2 AH2 + all-trans-beta-carotene + 2 O2 = 2 A + echinenone + 3
CC         H2O; Xref=Rhea:RHEA:55660, ChEBI:CHEBI:4746, ChEBI:CHEBI:13193,
CC         ChEBI:CHEBI:15377, ChEBI:CHEBI:15379, ChEBI:CHEBI:17499,
CC         ChEBI:CHEBI:17579; EC=1.14.99.63;
CC         Evidence={ECO:0000269|PubMed:16242201, ECO:0000269|PubMed:21398427,
CC         ECO:0000269|PubMed:22526507};
CC       PhysiologicalDirection=left-to-right; Xref=Rhea:RHEA:55661;
CC         Evidence={ECO:0000269|PubMed:16242201, ECO:0000269|PubMed:21398427,
CC         ECO:0000269|PubMed:22526507};
CC   -!- PATHWAY: Carotenoid biosynthesis. {ECO:0000305}.
CC   -!- INDUCTION: Induced by salt stress. {ECO:0000269|PubMed:16242201}.
CC   ---------------------------------------------------------------------------
CC   Copyrighted by the UniProt Consortium, see https://www.uniprot.org/terms
CC   Distributed under the Creative Commons Attribution (CC BY 4.0) License
CC   ---------------------------------------------------------------------------
DR   EMBL; AY603347; AAT35555.1; -; mRNA.
DR   AlphaFoldDB; Q6J3N5; -.
DR   GO; GO:0016705; F:oxidoreductase activity, acting on paired donors, with incorporation or reduction of molecular oxygen; IDA:UniProtKB.
DR   GO; GO:0016117; P:carotenoid biosynthetic process; IDA:UniProtKB.
DR   InterPro; IPR005804; FA_desaturase_dom.
DR   InterPro; IPR012171; Fatty_acid_desaturase.
DR   PANTHER; PTHR19353; PTHR19353; 2.
DR   Pfam; PF00487; FA_desaturase; 2.
PE   1: Evidence at protein level;
KW   Carotenoid biosynthesis; Oxidoreductase.
FT   CHAIN           1..320
FT                   /note="Beta-carotene 4-ketolase 3"
FT                   /id="PRO_0000452212"
SQ   SEQUENCE   320 AA;  35894 MW;  194EE30B2888FCDA CRC64;
     MHVASALMVE QKGSEAAASS PDVLRAWATQ YHMPSESSDA ARPALKHAYK PPASDAKGIT
     MALTIIGTWT AVFLHAIFQI RLPTSMDQLH WLPVSEATAQ LLGGSSSLLH IAAVFIVLEF
     LYTGLFITTH DAMHGTIALR NRQLNDLLGN ICISLYAWFD YSMLHRKHWE HHNHTGEVGK
     DPDFHKGNPG LVPWFASFMS SYMSLWQFAR LAWWAVVMQM LGAPMANLLV FMAAAPILSA
     FRLFYFGTYL PHKPGPGPAA GSQVMAWFRA KTSEASDVMS FLTCYHFDLH WEHHRWPFAP
     WWQLPHCRRL SGRGLVPALA