Rac homologues and compartmentalized phosphatidylinositol 4, 5-bisphosphate act in a common pathway to regulate polar pollen tube growth

• Published in: The Journal of cell biology Vol. 145; no. 2; pp. 317 - 330
• Main Authors: Kost, B. (National University of Singapore, Singapore.), Lemichez, E, Spielhofer, P, Hong, Y, Tolias, K, Carpenter, C, Chua, N.H
• Format: Journal Article
• Language: English
• Published: United States Rockefeller University Press 19-04-1999; The Rockefeller University Press
• Subjects: Actins; ADN; Amino Acid Sequence; AMINO ACID SEQUENCES; Antibodies; Arabidopsis - physiology; Arabidopsis - ultrastructure; ARABIDOPSIS THALIANA; BIOCHEMISTRY; BIOCHIMIE; BIOQUIMICA; CELL MEMBRANES; Cells, Cultured; Cellular biology; CHEMICAL COMPOSITION; CITOPLASMA; COMPLEMENTARY DNA; COMPOSICION QUIMICA; COMPOSITION CHIMIQUE; CRECIMIENTO; CROISSANCE; CYTOCHEMISTRY; CYTOPLASM; CYTOPLASME; DNA; Enzymes; FOSFOLIPIDOS; GENBANK/AL022023; GENBANK/AL022373; GENE; GENES; Glycosylation; GROWTH; GTP Phosphohydrolases - metabolism; GTP-Binding Proteins - chemistry; GTP-Binding Proteins - genetics; GTP-Binding Proteins - metabolism; GUANOSINETRIPHOSPHATASE; HIDROLASAS; HYDROLASE; HYDROLASES; Isoenzymes - metabolism; KINASES; Lipids; MEMBRANAS CELULARES; MEMBRANE CELLULAIRE; MOLECULAR SEQUENCE DATA; Nicotiana; NICOTIANA TABACUM; NUCLEOTIDE SEQUENCE; PHOSPHATIDE; Phosphatidylinositol 4,5-Diphosphate - metabolism; PHOSPHATIDYLINOSITOL MONOPHOSPHATE KINASE; Phosphatidylinositols; Phospholipase C delta; PHOSPHOLIPIDS; Plant growth regulators; Plant Proteins - metabolism; Plant Structures; PLANTAS TRANSGENICAS; PLANTE TRANSGENIQUE; Plants, Toxic; PLASMA MEMBRANES; Pollen; Pollen - physiology; Pollen - ultrastructure; POLLEN TUBES; PYROPHOSPHATASES; rac GTP-Binding Proteins; Recombinant Proteins - metabolism; Regular; Secretion; SECUENCIA NUCLEOTIDICA; Sequence Alignment; Sequence Homology, Amino Acid; SEQUENCE NUCLEOTIDIQUE; STRUCTURAL GENES; Transfection; TRANSFERASAS; TRANSFERASE; TRANSFERASES; TRANSGENIC PLANTS; TUBE DU POLLEN; TUBOS POLINICOS; Type C Phospholipases - metabolism
• ISSN: 0021-9525; 1540-8140
• DOI: 10.1083/jcb.145.2.317

Pollen tube cells elongate based on actin-dependent targeted secretion at the tip. Rho family small GTPases have been implicated in the regulation of related processes in animal and yeast cells. We have functionally characterized Rac type Rho family proteins that are expressed in growing pollen tubes. Expression of dominant negative Rac inhibited pollen tube elongation, whereas expression of constitutive active Rac induced depolarized growth. Pollen tube Rac was found to accumulate at the tip plasma membrane and to physically associate with a phosphatidylinositol monophosphate kinase (PtdIns P-K) activity. Phosphatidylinositol 4,5-bisphosphate (PtdIns 4,5-P2), the product of PtdIns P-Ks, showed a similar intracellular localization as Rac. Expression of the pleckstrin homology (PH)-domain of phospholipase C (PLC)-δ 1, which binds specifically to PtdIns 4,5-P2, inhibited pollen tube elongation. These results indicate that Rac and PtdIns 4,5-P2 act in a common pathway to control polar pollen tube growth and provide direct evidence for a function of PtdIns 4,5-P2 compartmentalization in the regulation of this process.