Synthesis and secretion of an Erwinia chrysanthemi pectate lyase in Saccharomyces cerevisiae regulated by different combinations of bacterial and yeast promoter and signal sequences

Nine different expression-secretion cassettes, comprising novel combinations of yeast and bacterial gene promoters and secretion signal sequences, were constructed and evaluated. A pectate lyase-encoding gene (pelE) from Erwinia chrysanthemi was inserted between each one of these expression-secretion cassettes and a yeast gene terminator, generating recombinant yeast-integrating shuttle plasmids pAMSl through pAMS9. These YIp5-derived plasmids were transformed and stably integrated into the genome of a laboratory strain of Saccharomyces cerevisiae, and the pectate lyase production was monitored. Transcription initiation signals for pelE expression were derived from the yeast alcohol dehydrogenase (ADC1_P), the yeast mating pheromone α-factor (MFα1_P) and the Bacillus amyloliquefaciens α-amylase (AMY_P) gene promoters. The transcription termination signals were derived from the yeast tryptophan synthase gene terminator (TRP5_T). Secretion of pectate lyase (PLe) was directed by the signal sequences of the yeast mating pheromone α-factor (MFα1_S), B. amyloliquefaciens α-amylase (AMY_S) and Er. chrysanthemi pectate lyase (pelE_S). The ADCl_P-MFα1_S expression-secretion system proved to be the most efficient control cassette for the expression of pelE and the secretion of PLe in S. cerevisiae.