International Dairy Journal, 23 (2), pp. 91-98.
Chang, O.K., Perrin, C., Galia, W., Saulnier, F., Miclo, L., Roux, E., Driou, A., Humbert, G., Dary, A.
2012
PrtS is the sole cell envelope protease (CEP) characterized in Streptococcus thermophilus. It is believed that it is anchored to the cell wall by sortase A (SrtA) through the LPXTG motif present at its C-terminus. Two soluble proteases corresponding to PrtS in its proenzyme and mature form were detected in the supernatant of S. thermophilus strain 4F44. In this strain, 60% of the PrtS molecules are anchored to the cell wall and 40% released in the medium. Such a release might result from a partial deficiency in the strain 4F44 of SrtA, even if its sequence slightly differs from that of S. thermophilus strain LMD-9, in which PrtS is anchored. Indeed, the presence of an intact LPXTG motif at the C-terminus of the released proteases showed that the linking process driven by SrtA did not occur and these proteases were not released by proteolysis after their anchoring.