Cloning and expression of the Lactococcus lactis subsp. Cremoris SK11 gene encoding an extracellular serine proteinase

摘要: The Lactococcus lactis subsp. cremoris SK11 plasmid-located prtP gene, encoding a cell-envelope-located proteinase (PrtP) that degrades alpha s1-, beta- and kappa-casein, was identified in lambda EMBL3 gene library Escherichia coli using immunological methods. complete could not be cloned E. L. on high-copy-number plasmid vectors. However, low-copy-number vector, the strains MG1363 SK1128, proteinase-deficient derivatives of 712 SK11, respectively. deficiency these hosts complemented to wild-type (wt) levels by gene. caseinolytic specificity specified identical encoded wt plasmid, pSK111. expression recombinant plasmids containing 3' 5' deletions analyzed with specific attention directed towards location products. In this way signals were localized overproduction obtained lactis. Furthermore, region at C terminus PrtP which is involved cell-envelope attachment lactococci. A deletion derivative constructed specifies C-terminally truncated well expressed fully secreted into medium, still shows same capacity degrade kappa-casein.