A single gene for lycopene cyclase, phytoene synthase, and regulation of carotene biosynthesis in Phycomyces

Abstract

Previous complementation and mapping of mutations that change the usual yellow color of the Zygomycete Phycomyces blakesleeanus to white or red led to the definition of two structural genes for carotene biosynthesis. We have cloned one of these genes, carRA , by taking advantage of its close linkage to the other, carB , responsible for phytoene dehydrogenase. The sequences of the wild type and six mutants have been established, compared with sequences in other organisms, and correlated with the mutant phenotypes. The carRA and carB coding sequences are separated by 1,381 untranslated nucleotides and are divergently transcribed. Gene carRA contains separate domains for two enzymes, lycopene cyclase and phytoene synthase, and regulates the overall activity of the pathway and its response to physical and chemical stimuli from the environment. The lycopene cyclase domain of carRA derived from a duplication of a gene from a common ancestor of fungi and Brevibacterium linens ; the phytoene synthase domain is similar to the phytoene and squalene synthases of many organisms; but the regulatory functions appear to be specific to Phycomyces .

Directed evolution of mevalonate kinase inEscherichia coliby random mutagenesis for improved lycopene

“…The interaction between Lys-12 and Asp-202 was of particular interest, as there is a salt bridge linking these two residues. Lys-12 forms a close interaction with the ATP g-PO 4 . The carboxyl group of MVA binds nearby residues Arg-248, Thr-350, and Ala-352.…”

“…2,3 Despite the well-established lycopene production protocols, the long growth cycle of the tomato is disadvantageous, as is the addition of cyclase inhibitors to B. trispora which is required to inhibit the cyclase function of the bifunctional lycopene cyclase/phytoene synthase (carRA), 4 which can be problematic from a food safety perspective. Alternative methods of lycopene production must be developed in order to avoid these issues.…”

Contained metabolic engineering in tomatoes by expression of carotenoid biosynthesis genes from the plastid genome

“…In addition to the lycopene β ‐cyclase gene ( crtY ) from the carotenoid‐producing eubacterium Erwinia herbicola , we selected the carRA gene from the zygomycete fungus Phycomyces blakesleeanus . This gene is particularly interesting in that the encoded protein has been suggested to be bifunctional (Arrach et al. , 2001): its N‐terminal domain carries lycopene β ‐cyclase activity, whereas the C‐terminal domain harbours phytoene synthase activity.…”

“…, 2001): its N‐terminal domain carries lycopene β ‐cyclase activity, whereas the C‐terminal domain harbours phytoene synthase activity. The protein has been suggested to undergo post‐translational processing by proteolytic cleavage, separating the two enzyme activities into distinct polypeptide chains (Arrach et al. , 2001).…”

Lateral Transfer of Genes from Fungi Underlies Carotenoid Production in Aphids

“…Such transfer preserved the gene arrangement observed in certain fungi, in which the entire region, encompassing divergently transcribed carotenoid desaturase and carotenoid synthase-carotenoid cyclase loci, comprises only about 5 kilobases (kb) (25,26). The aphid copies have much larger introns and larger intergenic spacers (Table 1 and fig.…”