원문정보
초록
영어
With the visual system based on color C40 carotenoids formation, the 12 clones having the altered
specificity of C15 FPP to C20 GGPP were isolated from the mutant library of farnesyl diphosphate
(FPP, C15) synthase (IspA) of Escherichia coli. Some of the mutant IspA clones are reminiscences of the significance of positions and types of amino acids near or before the conserved first aspartate rich motif (FARM), which is generally known as one of the controlling mechanism for chain elongation reaction of all prenyl synthases. One IspA mutant carries a mutation at 2nd amino acid upstream of the conserved region IV, which recently was found to be important region controlling the chain elongation of Type III GGPP synthase. Another IspA mutant carries mutations near the conserved second aspartate rich motif (SARM). The product formation and profiles of wild-type and mutant IspA were examined by in vitro assay of purified enzymes. The model structures of the IspA mutants indicate that the product specificity may be controlled by alternation of the catalytic site of the enzymes that are spaciously related with the conserved regions.