4rep
Crystal Structure of gamma-carotenoid desaturaseCrystal Structure of gamma-carotenoid desaturase
Structural highlights
FunctionCRTDH_NONDD Catalyzes the introduction of a C-3,4 double bond into 1'-hydroxy-gamma-carotene and rhodopin (1-hydroxylycopene) to yield 1'-hydroxytorulene and (3E)-3,4-didehydrorhodopin, respectively (By similarity). Can also use 1-hydroxy-all-trans-1,2-dihydro-neurosporene, 1,1'-dihydroxy-1,1',2,2'-tetrahydroneurosporene and 1,1'-dihydroxy-1,1',2,2'-tetrahydrolycopene (By similarity). Probably involved in the synthesis of myxol, a gamma-carotene derivative (Probable). May use FAD as a proton acceptor (Probable).[UniProtKB:Q7WT72][1] Publication Abstract from PubMedThe gamma-carotenoids, such as myxol and saproxanthin, have a high potential to be utilized in nutraceutical and pharmaceutical industries for their neuro-protective and antioxidant effects. CrtD is involved in the production of gamma-carotenoids by desaturating the C3'-C4' position of 1'-OH-gamma-carotenoid. We determined the crystal structure of CrtD from Nonlabens dokdonensis DSW-6 (NdCrtD), the first structure of CrtD family enzymes. The NdCrtD structure was composed of two distinct domains, an FAD-binding domain and a substrate-binding domain, and the substrate-binding domain can be divided into two subdomains, a Rossmann fold-like subdomain and a lid subdomain. Although the FAD-binding domain showed a structure similar to canonical FAD-containing enzymes, the substrate-binding domain exhibited a novel structure to constitute a long and hydrophobic tunnel with a length of approximately 40A. The molecular docking-simulation reveals that the tunnel provides an appropriate substrate-binding site for the carotenoid such as 1'-OH-gamma-carotene with a length of approximately 35A. We could predict residues related to recognize the 1'-hydroxyl group and to stabilize the hydrophobic end without hydroxyl group. Moreover, we suggest that the flexible entrance loop may undergo an open-closed formational change during the binding of the substrate. Crystal structure of 1'-OH-carotenoid 3,4-desaturase from Nonlabens dokdonensis DSW-6.,Ahn JW, Kim KJ Enzyme Microb Technol. 2015 Sep;77:29-37. doi: 10.1016/j.enzmictec.2015.05.005., Epub 2015 May 22. PMID:26138397[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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