A mutant strain of a methylotrophic organism and a process for the production of a protein in a methylotrophic organism.

摘要

The present invention relates to a mutant strain of a methylotrophic organism, a process for the production of a protein in a methylotrophic organism and a method for the selection of methanol oxidase deficient mutants of methylotrophic organisms. The present invention provides a mutant strain of a methylotrophic organism wherein the original chromosome of said mutant is defective in effecting synthesis of active molecules of at least one protein encoded by a methanol inducible gene. Upon introduction of at least one, preferably more than one expression casette, wherein each of said expression casettes comprises an regulon of a methanol inducible gene or a functionally equivalent sequence, a DNA sequence coding for a protein to be expressed, and optionally a terminator, and wherein expression of said DNA sequence is under control of said regulon a strain is obtained, which shows a remarkable over-expression of the protein encoded by the gene of the expression casette. These strains are well suited for production of pure proteins, such as methanol oxidases free of catalase.