Information on EC 1.3.99.27 - 1-hydroxycarotenoid 3,4-desaturase

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1-hydroxy monocyclic carotenoid 3,4-dehydrogenase

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acyclic carotenoid 3,4-desaturase

CrtD

11 entries

DDD_2394

hydroxyneurosporene desaturase

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P99-3 CrtD

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Biosynthesis of secondary metabolites, Carotenoid biosynthesis

1-hydroxy-1,2-dihydrolycopene + acceptor = 1-hydroxy-3,4-didehydro-1,2-dihydrolycopene + reduced acceptor

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KEGG

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Carotenoid biosynthesis, Carotenoid biosynthesis

1-hydroxy-1,2-dihydrolycopene:acceptor oxidoreductase

The enzymes from Rubrivivax gelatinosus and Rhodobacter sphaeroides prefer the acyclic carotenoids (e.g. 1-hydroxy-1,2-dihydroneurosporene, 1-hydroxy-1,2-dihydrolycopene) as substrates. The conversion rate for the 3,4-desaturation of the monocyclic 1'-hydroxy-1',2'-dihydro-gamma-carotene is lower [2,3]. The enzyme from the marine bacterium strain P99-3 shows high activity with the monocyclic carotenoid 1'-hydroxy-1',2'-dihydro-gamma-carotene [1]. The enzyme from Rhodobacter sphaeroides utilizes molecular oxygen as the electron acceptor in vitro [3]. However, oxygen is unlikely to be the natural electron acceptor under anaerobic conditions.

1'-hydroxy-gamma-carotene + acceptor

1'-hydroxytorulene + reduced acceptor

4 entries

1,1'-dihydroxy-3,4-didehydrolycopene + acceptor

1,1'-dihydroxy-3,4,3',4'-tetradehydrolycopene + reduced acceptor

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38% conversion

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?

1,1'-dihydroxyneurosporene + acceptor

1'-hydroxy-1-demethylspheroidene + reduced acceptor

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39% conversion

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?

1-hydroxy-1,2-dihydrorhodopin + acceptor

1-hydroxy-3,4-didehydro-1,2-dihydrorhodopin + reduced acceptor

1-hydroxy-3',4'-didehydrolycopene + acceptor

1-hydroxy-3,4,3',4'-tetradehydrolycopene + reduced acceptor

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28% conversion

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?

1-hydroxy-3,4-didehydrolycopene + acceptor

1-hydroxy-3,4,3',4'-tetradehydrolycopene + reduced acceptor

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712535

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?

1-hydroxy-zeta-carotene + acceptor

1-hydroxy-3,4-didehydro-zeta-carotene + reduced acceptor

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15% conversion

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?

1-hydroxylycopene + acceptor

1-hydroxy-3,4-didehydrolycopene + reduced acceptor

3 entries

1-hydroxyneurosporene + acceptor

1-demethylspheroidene + reduced acceptor

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47% conversion. The 3,4-desaturation reaction can only occur with mono-1-hydroxy carotenoids at a Psi-end group or with 1,1'-dihydroxy derivatives carrying a 3'4'-double bond. In addition, 1-hydroxy-zeta-carotene could also be converted by the desaturase. Enzyme kinetic studies show a substrate preference of 1-hydroxyneurosporene over 1-hydroxylycopene

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?

1-hydroxyneurosporene + acceptor

demethylspheroidene + reduced acceptor

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when O2 is depleted less than 10% of the specific activity is retained. It is rather unlikely that molecular oxygen is the genuine cofactor for hydroxyneurosporene desaturation reactions in Rhodobacter cells when they reach their maximum carotenoid content under anaerobic conditions. Consequently, another, as-yet-unknown electron acceptor may exist in Rhodobacter species that replaces molecular oxygen during anaerobic growth

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?

1-methoxy-1'-hydroxy-3,4-didehydrolycopene + acceptor

1-methoxy-1'-hydroxy-3,4,3',4'-tetradehydrolycopene + reduced acceptor

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37% conversion

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?

additional information

?

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1'-hydroxy-gamma-carotene + acceptor

1'-hydroxytorulene + reduced acceptor

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the enzyme is involved in myxol biosynthesis

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?

1-hydroxy-1,2-dihydrorhodopin + acceptor

1-hydroxy-3,4-didehydro-1,2-dihydrorhodopin + reduced acceptor

FAD

the FAD-binding site is located at the G-x-G-x-x-G nucleotide-binding motif, comprising residues Gly8-Ala9-Gly10-Ile11-Gly12-Gly13

additional information

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NAD+, NADP+, and flavin adenine dinucleotide have no influence on enzymatic activity. When O2 is depleted less than 10% of the specific activity is retained. It is rather unlikely that molecular oxygen is the genuine cofactor for hydroxyneurosporene desaturation reactions in Rhodobacter cells when they reach their maximum carotenoid content under anaerobic conditions. Consequently, another, as-yet-unknown electron acceptor may exist in Rhodobacter species that replaces molecular oxygen during anaerobic growth

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0.019

1,1'-dihydroxyneurosporene

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pH 7.8, 28°C

0.04

1-hydroxylycopene

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pH 7.8, 28°C

0.0134 - 0.025

1-hydroxyneurosporene

7.8

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assay at

8

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assay at

28

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assay at

30

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assay at

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Nonlabens dokdonensis DSW-6

UniProt

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UniProt

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Rhodoplanes elegans AS130

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Rhodoplanes pokkaliisoli

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Rhodoplanes pokkaliisoli JA415

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Rhodoplanes serenus TUT3530

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Rhodoplanes tepidamans

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711126, 712535

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evolution

malfunction

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the deletion mutant shows a different carotenoid pattern than the wild-type enzyme

physiological function

4 entries

55000

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x * 55000, calculated from sequence

58000

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x * 58000, SDS-PAGE

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to 1.97 A resolution. CrtD structure is composed of an FAD-binding domain and a substrate-binding domain, which can be divided into two subdomains, a Rossmann fold-like subdomain and a lid subdomain. The substrate-binding domain constitutes a long and hydrophobic tunnel with a length of about 40 A. The tunnel provides an appropriate substrate-binding site for the carotenoid such as 1'-OH-gamma-carotene with a length of about 35 A

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expressed in Escherichia coli

expression in Escherichia coli

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synthesis