ACTIN BINDING PROTEIN 29 from Lilium pollen plays an important role in dynamic actin remodeling.
Villin/gelsolin/fragmin superfamily proteins have been shown to function in tip-growing plant cells. However, genes encoding gelsolin/fragmin do not exist in the Arabidopsis thaliana and rice (Oryza sativa) databases, and it is possible that these proteins are encoded by villin mRNA splicing variants. We cloned a 1006-bp full-length cDNA from Lilium longiflorum that encodes a 263-amino acid predicted protein sharing 100% identity with the N terminus of 135-ABP (Lilium villin) except for six C-terminal amino acids. The deduced 29-kD protein, Lilium ACTIN BINDING PROTEIN29 (ABP29), contains only the G1 and G2 domains and is the smallest identified member of the villin/gelsolin/fragmin superfamily. The purified recombinant ABP29 accelerates actin nucleation, blocks barbed ends, and severs actin filaments in a Ca(2+)- and/or phosphatidylinositol 4,5-bisphosphate-regulated manner in vitro. Microinjection of the protein into stamen hair cells disrupted transvacuolar strands whose backbone is mainly actin filament bundles. Transient expression of ABP29 by microprojectile bombardment of lily pollen resulted in actin filament fragmentation and inhibited pollen germination and tube growth. Our results suggest that ABP29 is a splicing variant of Lilium villin and a member of the villin/gelsolin/fragmin superfamily, which plays important roles in rearrangement of the actin cytoskeleton during pollen germination and tube growth.
Xiang
Yun
Y
Key Laboratory of Cell Proliferation and Regulation Biology of Ministry of Education and College of Life Science, Beijing Normal University, Beijing, PR China.
Huang
Xi
X
Wang
Ting
T
Zhang
Yan
Y
Liu
Qinwen
Q
Hussey
Patrick J
PJ
Ren
Haiyun
H
D008841:Actin Cytoskeleton / Q000187:drug effects / Q000378:metabolism; D000199:Actins / Q000378:metabolism*; D000595:Amino Acid Sequence; D002118:Calcium / Q000494:pharmacology; D002457:Cell Extracts; D003599:Cytoskeleton / Q000187:drug effects; D018076:DNA, Complementary / Q000302:isolation & purification; D018260:Gelsolin; D018525:Germination / Q000187:drug effects; D027762:Lilium / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D008840:Microfilament Proteins; D008969:Molecular Sequence Data; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000494:pharmacology; D010940:Plant Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D011058:Pollen / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D053205:Pollen Tube / Q000187:drug effects / Q000254:growth & development; D011485:Protein Binding / Q000187:drug effects; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000302:isolation & purification; D016415:Sequence Alignment
D000199:Actins; D002457:Cell Extracts; D018076:DNA, Complementary; D018260:Gelsolin; D008840:Microfilament Proteins; D019269:Phosphatidylinositol 4,5-Diphosphate; D010940:Plant Proteins; D011994:Recombinant Proteins; C026615:villin; D002118:Calcium