Developmental signal transduction pathways uncovered by genetic suppressors

Developmental signal transduction pathways uncovered by genetic suppressors

Center for Molecular Genetics, Department of Biology, University of California at San Diego, La Jolla, CA 92093

Abstract

We have found conditions for saturation mutagenesis by restriction enzyme mediated integration that result in plasmid tagging of disrupted genes. Using this method we selected for mutations in genes that act at checkpoints downstream of the intercellular signaling system that controls encapsulation in Dictyostelium discoideum. One of these genes, mkcA, is a member of the mitogen-activating protein kinase cascade family while the other, regA, is a novel bipartite gene homologous to response regulators in one part and to cyclic nucleotide phosphodiesterases in the other part. Disruption of either of these genes results in partial suppression of the block to spore formation resulting from the loss of the prestalk genes, tagB and tagC. The products of the tag genes have conserved domains of serine proteases attached to ATP-driven transporters, suggesting that they process and export peptide signals. Together, these genes outline an intercellular communication system that coordinates organismal shape with cellular differentiation during development.

Footnotes

↵ * To whom reprint requests should be addressed. e-mail: wloomis{at}ucsd.edu.
J. T. Bonner, Princeton University, Princeton, NJ
Abbreviations: REMI, restriction enzyme mediated integration; MAP, mitogen-activating protein; MHC, major histocompatibility complex; MDR, multiple drug resistance.

Data deposition: The sequences reported in this paper have been deposited in the GenBank data base [accession numbers U60086U60086 (tagC), U60168U60168 (prtC), U60169U60169 (mkcA), and U60170U60170 (regA)].