FUNCTIONAL-ANALYSIS OF THE CATALYTIC SUBUNIT OF DICTYOSTELIUM PKA IN-VIVO

The catalytic subunit of the CAMP-dependent protein kinase (PKA) from Dictyostelium discoideum contains several domains, including an unusua lly long N-terminal extension preceding a highly conserved catalytic c ore. We transformed the aggregationless PkaC-null strain with several deletion constructs of both domains. Strains transformed with genes ex pressing catalytically-inactive polypeptides could not rescue developm ent. Cotransformation with constructs encoding the N-terminal extensio n and the catalytic core, both unable to rescue development by themsel ves, yielded transformants able to proceed to late development. A 27-a mino acid long hydrophobic region, immediately upstream of the catalyt ic core, was found indispensable for PKA function. A putative role of this sequence in the acquisition of the active conformation of the pro tein is discussed. (C) 1998 Elsevier Science Ireland Ltd.