TRANSFORMATION WITH VECTORS HARBORING THE NEO(R) SELECTION MARKER INDUCES GERMINATION-SPECIFIC ADENYLYLCYCLASE ACTIVITY IN DICTYOSTELIUM CELLS

Dictyostelium cells express an aggregative adenylylcyclase (ACA), resp onsible for oscillatory cAMP signaling, and a spore germination-specif ic adenylycyclase (ACG), Overexpression of PKA regulatory (R) subunits blocks oscillatory cAMP signaling but increases basal cAMP levels, wh ile neither ACA nor ACG mRNA could be detected, To test whether a nove l type of adenylylcyclase (AC) was responsible for cAMP synthesis, dom inant-negative PKA-R subunits (PKA-R(M)) and control R-subunits (PKA-R (c)) were overexpressed in ACA null mutants, Both transformations as w ell as transformation with an unrelated vector, carrying the same NEO( R) selection marker, induced an AC activity in growing cells with the biochemical characteristics of ACG. Similar vectors with a different U RA selection marker did not increase AC activity. We conclude that the aminoglycoside phosphotransferase encoded by the very commonly used N EO(R) selection marker induces ectopic ACG; activity in Dictyostelium cells, (C) 1995 Academic Press, Inc.