We have isolated a number of mutants deficient in activity of the vacuolar hydrolase proteinase A (PrA). The mutations were sequenced and although they all map in the PEP4 gene, which encodes the precursor to PrA, three distinguishable phenotypes have surfaced. The properties of the pep4-7 missense mutant suggested that the activation of the precursor to proteinase A is due to an autocatalytic cleavage. PrA active site mutations were constructed and resulted in accumulation of PrA antigen in the inactive precursor form. Although protease B (PrB), another vacuolar hydrolase, is not required for the production of active PrA, the active form of PrA that accumulates in a strain lacking PrB is larger than that found in a strain containing active PrB. We have purified this larger form of PrA and determined that it bears 7 additional amino acids at its NH2 terminus. It has become apparent from all the studies performed on the maturation pathway of the vacuolar hydrolases that there is a great deal of redundancy built into the system.

• PMID: 8473342
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Reference Type

Journal Article | Research Support, Non-U.S. Gov't | Research Support, U.S. Gov't, P.H.S.

Authors

Woolford CA, Noble JA, Garman JD, Tam MF, Innis MA, Jones EW

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