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Cloning and sequencing of the gene encoding X‐prolyl‐dipeptidyl aminopeptidase (PepX) from Streptococcus thermophilus strain ACA‐DC 4
Author(s) -
Anastasiou R.,
Papadelli M.,
Georgalaki M.D.,
Kalantzopoulos G.,
Tsakalidou E.
Publication year - 2002
Publication title -
journal of applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 1364-5072
DOI - 10.1046/j.1365-2672.2002.01659.x
Subject(s) - streptococcus thermophilus , biology , biochemistry , gene , peptide sequence , aminopeptidase , nucleic acid sequence , open reading frame , microbiology and biotechnology , structural gene , molecular cloning , amino acid , mutant , lactobacillus , leucine , fermentation
Aims: To clone and sequence the pepX gene from Streptococcus thermophilus.Methods and Results: Three pairs of primers were used in polymerase chain reactions using as template the total DNA from Strep. thermophilus ACA‐DC 4 in order to amplify, clone and sequence the pepX gene. Sequence analysis revealed an open reading frame of 2268 nucleotides encoding a protein of 755 amino acids. The calculated molecular mass of 85 632 Da agreed well with the apparent molecular mass of 80 000 Da previously determined by sodium dodecyl sulphate‐polyacrylamide gel electrophoresis and gel filtration for the monomeric form of the purified enzyme. Conclusions: The pepX gene from Strep. thermophilus ACA‐DC 4 was cloned and sequenced. The PepX protein showed significant sequence similarity with PepX enzymes from other lactic acid bacteria and contained a motif which was almost identical with the active site motif of the serine‐dependent PepX family. Significance and Impact of the Study: There are economic and technological incentives for accelerating and controlling the process of cheese ripening. To achieve this, starters may be modified by introducing appropriate genes from other food‐grade bacteria. New or additional peptidase activities may alter or improve the proteolytic properties of lactic acid bacteria.