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lycopene cyclase domain This domain is often repeated twice within the same polypeptide, as is observed in Archaea, Thermus, Sphingobacteria and Fungi. In the fungal sequences, this tandem domain pair is observed as the N-terminal half of a bifunctional protein, where it has been characterized as a lycopene beta-cyclase and the C-terminal half is a phytoene synthetase. In Myxococcus and Actinobacterial genomes this domain appears as a single polypeptide, tandemly repeated and usually in a genomic context consistent with a role in carotenoid biosynthesis. It is unclear whether any of the sequences in this family truly encode lycopene epsilon cyclases. However a number are annotated as such. The domain is generally hydrophobic with a number of predicted membrane spanning segments and contains a distinctive motif (hPhEEhhhhhh). In certain sequences one of either the proline or glutamates may vary, but always one of the tandem pair appear to match this canonical sequence exactly. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",