Plant profilins rescue the aberrant phenotype of profilin-deficient Dictyostelium cells.
To characterize the function of plant profilins in vivo, we expressed two pollen specific Zea mays (maize) profilin isoforms in profilin-minus Dictyostelium discoideum mutants. In maize, profilins exist as a multigene family containing 4 or more members which are highly similar to each other but substantially less similar to profilins from animals and lower eukaryotes. Previously we have shown that D. discoideum profilin-minus cells have an aberrant phenotype due to defects in cell shape, cytokinesis, and development. These defects could be rescued by introducing the pollen-specific profilins 1 or 2 from maize using a newly constructed expression vector. Expression of the heterologous profilins in Dictyostelium clones was assayed by affinity purification of the pollen profilins with poly-proline agarose and by immunoblotting with a polyclonal antiserum raised against maize pollen profilin. In contrast to the profilin-minus mutants, Dictyostelium cells expressing plant profilins showed normal cell shape, contained less F-actin, and were able to form fruiting bodies. These data provide genetic evidence that maize pollen profilins, even though they are specific for a distinct developmental stage, share functional properties with profilin from a lower eukaryote and apparently act as G-actin-sequestering proteins in this system.
Karakesisoglou
I
I
Institut fur Zellbiologie, Ludwig-Maximilians-Universitat Munchen, Munich, Federal Republic of Germany.
Schleicher
M
M
Gibbon
B C
BC
Staiger
C J
CJ
D000818:Animals; D005075:Biological Evolution; D002455:Cell Division / Q000187:drug effects; D003285:Contractile Proteins; D004023:Dictyostelium / Q000187:drug effects* / Q000235:genetics; D017353:Gene Deletion; D005800:Genes, Fungal; D005822:Genetic Vectors; D008840:Microfilament Proteins / Q000032:analysis / Q000172:deficiency / Q000494:pharmacology*; D010641:Phenotype; D010940:Plant Proteins / Q000032:analysis / Q000494:pharmacology*; D051304:Profilins; D013045:Species Specificity; D014162:Transfection; D003313:Zea mays / Q000737:chemistry
D003285:Contractile Proteins; D008840:Microfilament Proteins; D010940:Plant Proteins; D051304:Profilins