Identification of a suppressor of the Dictyostelium profilin-minus phenotype as a CD36/LIMP-II homologue

J Cell Biol. 1999 Apr 5;145(1):167-81. doi: 10.1083/jcb.145.1.167.

Abstract

Profilin is an ubiquitous G-actin binding protein in eukaryotic cells. Lack of both profilin isoforms in Dictyostelium discoideum resulted in impaired cytokinesis and an arrest in development. A restriction enzyme-mediated integration approach was applied to profilin-minus cells to identify suppressor mutants for the developmental phenotype. A mutant with wild-type-like development and restored cytokinesis was isolated. The gene affected was found to code for an integral membrane glycoprotein of a predicted size of 88 kD containing two transmembrane domains, one at the NH2 terminus and the other at the COOH terminus. It is homologous to mammalian CD36/LIMP-II and represents the first member of this family in D. discoideum, therefore the name DdLIMP is proposed. Targeted disruption of the lmpA gene in the profilin-minus background also rescued the mutant phenotype. Immunofluorescence revealed a localization in vesicles and ringlike structures on the cell surface. Partially purified DdLIMP bound specifically to PIP2 in sedimentation and gel filtration assays. A direct interaction between DdLIMP and profilin could not be detected, and it is unclear how far upstream in a regulatory cascade DdLIMP might be positioned. However, the PIP2 binding of DdLIMP points towards a function via the phosphatidylinositol pathway, a major regulator of profilin.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • CD36 Antigens / chemistry
  • Chromatography, Gel
  • Cloning, Molecular
  • Consensus Sequence
  • Contractile Proteins*
  • Dictyostelium / genetics*
  • Gene Expression Regulation
  • Gene Targeting
  • Genes, Protozoan*
  • Genes, Suppressor*
  • Lysosomes / chemistry
  • Membrane Glycoproteins / genetics*
  • Membrane Glycoproteins / physiology
  • Microfilament Proteins / deficiency
  • Microfilament Proteins / genetics
  • Microfilament Proteins / physiology*
  • Microscopy, Fluorescence
  • Molecular Sequence Data
  • Phenotype
  • Phosphatidylinositol 4,5-Diphosphate / metabolism
  • Polymorphism, Restriction Fragment Length
  • Profilins
  • Protozoan Proteins / genetics*
  • Protozoan Proteins / physiology
  • Recombination, Genetic
  • Sequence Homology, Amino Acid
  • Species Specificity

Substances

  • CD36 Antigens
  • Contractile Proteins
  • Membrane Glycoproteins
  • Microfilament Proteins
  • Phosphatidylinositol 4,5-Diphosphate
  • Profilins
  • Protozoan Proteins

Associated data

  • GENBANK/AF124329