ABSTRACT
A current hypothesis is that induction of SAP2 by self-generated cleavage products is optimal in the pH range 3.0-5.0 as this is the pH optimum of Sap2p. Thus. the amount of inducing peptides that is generated is likely to be at a maximum. Notably, induction of SAP2 by these peptides is poor at pH 2.5 or 6.0 even if they are artificially added to the growth medium. It has been speculated that this may be explained by a pH-dependent mechanism of monitoring these peptides on the cell surface or translocating the peptides into the cell. Accordingly. pH is directly involved in regulation of SAP2 expression but is not the dominating signal in a number of stimulating and repressing conditions [49]. In media with protein as the sole source of nitrogen, SAP2 is generally found to be the most abundantly expressed gene among a family of at least 10 secreted aspartyl proteinases of C. albicans [49].
