Temperature-sensitive inhibition of development in Dictyostelium due to a point mutation in the piaA gene

Barbara Pergolizzi, Barbara Peracino, James Silverman, Adriano Ceccarelli, Angelika Noegel, Peter Devreotes, Salvatore Bozzaro

Research output: Contribution to journalArticle

Abstract

The Dictyostelium mutant HSB1 is temperature-sensitive for development, undergoing aggregation and fruiting body formation at temperatures below 18°C but not above. In vivo G protein-linked adenylyl cyclase activation is defective in HSB1, and the enzyme is not stimulated in vitro by GTPγS; stimulation is restored upon addition of wild-type cytosol. Transfection with the gene encoding the cytosolic regulator PIA rescued the mutant. We excluded the possibility that HSB1 cells fail to express PIA and show that the HSB1 piaA gene harbors a point mutation, resulting in the amino acid exchange G917D. Both wild-type and HSB1 cells were also transfected with the HSB1 piaA gene. The piaAHSB1 gene product displayed a partial inhibitory effect on wild-type cell development. We hypothesize that PIA couples the heterotrimeric G protein to adenylyl cyclase via two binding sites, one of which is altered in a temperature-sensitive way by the HSB1 mutation. When overexpressed in the wild-type background, PIAHSB1. competes with wild-type PIA via the nonmutated binding site, resulting in dominant-negative inhibition of development. Expression of GFP-fused PIA shows that PIA is homogeneously distributed in the cytoplasm of chemotactically moving cells.

Original languageEnglish (US)
Pages (from-to)18-26
Number of pages9
JournalDevelopmental biology
Volume251
Issue number1
DOIs
StatePublished - Jan 1 2002

Keywords

  • Adenylyl cyclase
  • Chemotaxis
  • Dictyostelium
  • G protein
  • Signal transduction
  • Slime molds

ASJC Scopus subject areas

  • Molecular Biology
  • Developmental Biology
  • Cell Biology

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