Polynucleotide molecule comprising mutated nucleotide sequence of Streptomyces avermitilis aveC allele, vector and host cell, method of making strain of S. avermitilis and process for producing avermectins and final composition

摘要

A polynucleotide molecule comprising a nucleotide sequence that is otherwise the same as the Streptomyces avermitilis aveC allele, the S. avermitilis AveC gene product-encoding sequence of plasmid pSE186 according to ATCC 209604 or the nucleotide sequence of the aveC ORF of S. avermitilis according to SEQ ID NO: 1, or a degenerate variant thereof, but which nucleotide sequence further comprises one or more mutations encoding an amino acid substitution at one or more amino acid residues corresponding to amino acid position 38, 48, 89, 99, 111, 136, 138, 154, 179, 228, 238, 289, or 298 of SEQ ID NO: 2, such that cells of S. avermitilis strain ATCC 53692 in which the wild-type aveC allele has been inactivated and that express the polynucleotide molecule comprising the mutated nucleotide sequence produce a class 2: 1 cyclohexyl B2: cyclohexyl B1 avermectins that is reduced from the ratio produced by cells of S. avermitilis strain ATCC 53692 that instead express only the wild-type aveC allele. A recombinant vector and a host cell, a method for making a strain of S. avermitilis, comprising mutating the aveC allele, a mutated cell this strain and a process for producing said avermectins and a final composition.