title: Absence of catalytic domain in a putative protein kinase C (PkcA) suppresses tip dominance in Dictyostelium discoideum.
abstract: A number of organisms possess several isoforms of protein kinase C but little is known about the significance of any specific isoform during embryogenesis and development. To address this we characterized a PKC ortholog (PkcA; DDB_G0288147) in Dictyostelium discoideum. pkcA expression switches from prestalk in mound to prespore in slug, indicating a dynamic expression pattern. Mutants lacking the catalytic domain of PkcA (pkcA(-)) did not exhibit tip dominance. A striking phenotype of pkcA- was the formation of an aggregate with a central hollow, and aggregates later fragmented to form small mounds, each becoming a fruiting body. Optical density wave patterns of cAMP in the late aggregates showed several cAMP wave generation centers. We attribute these defects in pkcA(-) to impaired cAMP signaling, altered cell motility and decreased expression of the cell adhesion molecules - CadA and CsaA. pkcA(-) slugs showed ectopic expression of ecmA in the prespore region. Further, the use of a PKC-specific inhibitor, GF109203X that inhibits the activity of catalytic domain phenocopied pkcA(-).
authors.affiliation: Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, India.
authors.forename: Wasima
authors.initials: W
authors.lastname: Mohamed
authors.affiliation: Department of Biological Sciences, Center for Translational and Basic Research, Hunter College and The Graduate Center of the City University of New York, New York, NY 10065, USA.
authors.forename: Sibnath
authors.initials: S
authors.lastname: Ray
authors.affiliation: Department of Biological Sciences, Center for Translational and Basic Research, Hunter College and The Graduate Center of the City University of New York, New York, NY 10065, USA.
authors.forename: Derrick
authors.initials: D
authors.lastname: Brazill
authors.affiliation: Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, India. Electronic address: rbaskar@iitm.ac.in.
authors.forename: Ramamurthy
authors.initials: R
authors.lastname: Baskar
mesh_terms: D000595:Amino Acid Sequence; D019521:Body Patterning; D020134:Catalytic Domain; D002448:Cell Adhesion; D002449:Cell Aggregation; D002633:Chemotaxis; D017124:Conserved Sequence; D000242:Cyclic AMP / Q000378:metabolism; D004023:Dictyostelium / Q000166:cytology / Q000201:enzymology* / Q000254:growth & development*; D008969:Molecular Sequence Data; D058105:Polymerization; D011493:Protein Kinase C / Q000737:chemistry*; D015800:Protozoan Proteins; D017386:Sequence Homology, Amino Acid; D059008:Time-Lapse Imaging
chemical_list: D015800:Protozoan Proteins; D000242:Cyclic AMP; D011493:Protein Kinase C
keywords: Dictyostelium; Differentiation; Morphogenesis; PKC; Tip dominance