MOLECULAR-CLONING OF YLPMR1, A SACCHAROMYCES-CEREVISIAE PMR1 HOMOLOG ENCODING A NOVEL P-TYPE SECRETORY PATHWAY CA(2-ATPASE, IN THE YEAST YARROWIA-LIPOLYTICA())

A novel P-type ATPase gene, Saccharomyces cerevisiae PMR1 homologue (Y lPMR1), has been cloned and sequenced in the yeast, Yarrowia lipolytic a. The putative gene product has 928 amino acids with a calculated mol ecular mass of 100 050 Da and a pI of 5.15. The deduced amino-acid seq uence analysis demonstrated that the cloned gene product contains all 10 of the conserved regions in P-type ATPases and exhibits 55% amino-a cid identity to the S. cerevisiae PMR1 gene product; however, it shows a relatively lower homology to PMCA (24%) and SERCA (33%), confirming the presence of a third class of Ca2+-ATPase (secretory pathway Ca2+- ATPase, SPCA). The YlPMR1-disrupted strain shows defective growth in l ow Ca2+ or EGTA-containing medium. In fact, a longer lag time (60 h) w as observed in YlPMR1-defective mutant cells during cultivation in EGT A-containing YPD medium. These growth defects were overcome by adding Ca2+ and Mn2+ into the medium. Interestingly, whereas Mn2+ inhibits gr owth of the control strain, it significantly improves the growth of Yl PMR1-disrupted cells. These results suggest an involvement of the YlPM R1 gene product in Ca2+ and Mn2+ ion homeostasis in Y. lipolytica. (C) 1997 Elsevier Science B.V.