Locus AT3G04870. Synonyms: ZDS1, CLB5, SPC1, PDE181. EC 1.3.5.6. Rhea:RHEA:30955.
ZDS is a nuclear-encoded, plastid-targeted flavoenzyme of the plant poly-cis
carotene-desaturation route. It catalyses the third of the four backbone steps
(PDS -> Z-ISO -> ZDS -> CRTISO) that convert 15-cis-phytoene to all-trans-lycopene.
Specifically ZDS introduces two double bonds (at C-7 and C-7') into
9,9'-di-cis-zeta-carotene, passing through the intermediate 7,9,9'-tri-cis-neurosporene,
to give 7,7',9,9'-tetra-cis-lycopene (pro-lycopene), using a lipophilic quinone
(plastoquinone) as electron acceptor.
Cached publications: PMID:9914519, 17468780, 24907342, 12938931 are abstract-only
(full_text_available: false); PMID:18431481, 20061580 have full text but neither names
ZDS/AT3G04870 in the cached body (they are large chloroplast-proteome/HDA datasets whose
curated ZDS hit I cannot re-derive from the text — I defer to the curator and support the
localization from UniProt).
Molecular function — 9,9'-di-cis-zeta-carotene desaturase activity (GO:0016719):
Core MF. Directly established biochemically by Bartley et al. 1999 (recombinant Arabidopsis
ZDS in E. coli): PMID:9914519 and
PMID:9914519.
IDA (PMID:9914519), IBA (PTN007457606, IBD-seeded by this gene itself), and IEA
(GO_REF:0000120; RHEA:30955, EC 1.3.5.6) rows all ACCEPT. QuickGO confirms GO:0016719 is
current and its definition matches the Rhea reaction exactly.
GO:0016491 oxidoreductase activity (IEA, InterPro IPR002937 amino-oxidase/FAD domain):
correct but generic parent. MODIFY -> GO:0016719 (the specific desaturase activity the
enzyme actually has; it is an oxidoreductase EC 1.3.5.6).
Process — carotenoid biosynthetic process (GO:0016117): IEA (IPR014103), plus two IMP
rows from the null-mutant phenotypes. spc1/zds: PMID:17468780 and
PMID:17468780.
clb5/zds: PMID:24907342.
All ACCEPT.
carotene biosynthetic process (GO:0016120): IBA (PTN007457606) and IDA (PMID:9914519,
qualifier acts_upstream_of_or_within). ACCEPT. Brief note: GO:0016120 is NOT a descendant
of GO:0016117 in the current ontology — left as-is, not "fixed".
lycopene biosynthetic process (GO:1901177) IDA (PMID:9914519): ACCEPT; pro-lycopene is
the direct product class, and UniProt pathway is "lycopene biosynthesis". QuickGO confirms
GO:1901177 current.
Localization — chloroplast (GO:0009507) HDA/IEA/ISM, chromoplast (GO:0009509) IEA,
chloroplast envelope (GO:0009941) HDA x2: all ACCEPT, consistent with
[file:ARATH/ZDS/ZDS-uniprot.txt "SUBCELLULAR LOCATION: Plastid, chloroplast. Plastid, chromoplast"].
The enzyme is membrane-associated (quinone-dependent; assayed on chromoplast membranes in
PMID:9914519). Envelope sub-localization comes from curated chloroplast-envelope proteomics
(PMID:12938931; PMID:20061580 AT_CHLORO).
The zds/clb5/spc1 mutants show leaf-developmental defects, photoprotection loss, ABA
deficiency and altered plastid-to-nucleus retrograde signalling
(PMID:17468780;
PMID:24907342).
These are indirect consequences of an apocarotenoid signal derived from the accumulated
ZDS substrates (phytofluene/zeta-carotene) cleaved by CCD4, not activities ZDS itself
performs: PMID:24907342.
By the participation test (ZDS does none of the work of leaf development / retrograde
signalling; the signal is made from its substrate when the enzyme is absent), no NEW
process terms for those roles are proposed. ABA deficiency is likewise downstream (carotenoid
supply for the ABA pathway), not ZDS catalysis.
GO:0052889 (specific "9,9'-di-cis-zeta-carotene desaturation to ...-lycopene") appears on
UniProt's DR lines but QuickGO reports it OBSOLETE — not used.
ACCEPT 15; MODIFY 1 (GO:0016491 -> GO:0016719); UNDECIDED 0; NEW 0.