Abstract: The present invention concerns a method of producing a desired gene product in a recombinant gene expression system, said method comprising expressing said gene from a Pm promoter-based expression system using at least two mutant elements selected from: (i) a mutant Pm promoter; (ii) a mutant mRNA leader; and (iii) a mutant XyIS; wherein said mutant elements each comprise one or more mutations which enhance expression of said desired gene. Particularly combinations of a mutant Pm promoter and a mutant mRNA leader are concerned. Isolated nucleic acid molecules, vectors, host cells, libraries, expression systems, methods of enhancing expression, obtaining nucleic acid molecules and identifying combination mutants which enhance expression, artificially constructed operons and their uses are also encompassed.

Abstract: The present invention concerns a method of producing a desired heterologous gene product wherein said heterologous gene product is expressed from a strong promoter, said method comprising expressing said gene using a mutant mRNA leader which comprises one or more mutations which enhance transcription of the gene. The invention also provides a mutant Pm mRNA leader sequence, and a vector and a library comprising the leader sequence. Methods of obtaining an mRNA mutant leader and identifying an mRNA mutant leader are encompassed, along with a vector for selection or identification of an mRNA leader mutant and a use thereof for screening.

Abstract: The present invention concerns a method of producing a desired heterologous gene product wherein said heterologous gene product is expressed from a strong promoter, said method comprising expressing said gene using a mutant mRNA leader which comprises one or more mutations which enhance transcription of the gene. The invention also provides a mutant Pm mRNA leader sequence, and a vector and a library comprising the leader sequence. Methods of obtaining an mRNA mutant leader and identifying an mRNA mutant leader are encompassed, along with a vector for selection or identification of an mRNA leader mutant and a use thereof for screening.

Abstract: The present invention concerns a method of producing a desired gene product in a recombinant gene expression system, said method comprising expressing said gene from a Pm promoter-based expression system using at least two mutant elements selected from: (i) a mutant Pm promoter; (ii) a mutant mRNA leader; and (iii) a mutant XyIS; wherein said mutant elements each comprise one or more mutations which enhance expression of said desired gene. Particularly combinations of a mutant Pm promoter and a mutant mRNA leader are concerned. Isolated nucleic acid molecules, vectors, host cells, libraries, expression systems, methods of enhancing expression, obtaining nucleic acid molecules and identifying combination mutants which enhance expression, artificially constructed operons and their uses are also encompassed.