The role of Arabidopsis SCAR genes in ARP2-ARP3-dependent cell morphogenesis.
The actin-nucleating ARP2-ARP3 complex controls cell shape in plants in many different cell types. Its activity is controlled by a multimeric complex containing BRK1 (also known as HSPC300), NAP1, SRA1, ABI and SCAR/WAVE. In this study, we focus on the function of the five putative SCAR homologues in Arabidopsis and we provide biochemical evidence that AtSCAR2 can activate the ARP2-ARP3 complex in vitro. Among the single mutants, mutations in only AtSCAR2 result in a subtle or weak phenotype similar to ARP2, ARP3 and other ;distorted' mutants. Double-mutant analysis revealed a redundancy with AtSCAR4. Systematic application of the yeast two-hybrid system and Bimolecular Fluorescence Complementation (BiFC) revealed a complex protein-interaction network between the ARP2-ARP3 complex and its genetically defined regulators. In addition to protein interactions known in other systems, we identified several new interactions, suggesting that SPIKE1 may be an integral component of the SCAR/WAVE complex and that SCAR proteins in plants might act as direct effectors of ROP GTPases.
Uhrig
Joachim F
JF
University of Köln, Botanical Institute III, Gyrhofstr. 15, 50931 Köln, Germany.
Mutondo
Moola
M
Zimmermann
Ilona
I
Deeks
Michael J
MJ
Machesky
Laura M
LM
Thomas
Philipp
P
Uhrig
Silke
S
Rambke
Claudia
C
Hussey
Patrick J
PJ
Hülskamp
Martin
M
D051376:Actin-Related Protein 2-3 Complex / Q000235:genetics / Q000378:metabolism*; D000251:Adenosine Triphosphatases / Q000378:metabolism; D017360:Arabidopsis / Q000378:metabolism / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D018797:Cell Cycle Proteins / Q000378:metabolism; D009024:Morphogenesis; D009154:Mutation; D011485:Protein Binding; D025941:Protein Interaction Mapping; D051300:Wiskott-Aldrich Syndrome Protein Family / Q000378:metabolism / Q000502:physiology*
D051376:Actin-Related Protein 2-3 Complex; D029681:Arabidopsis Proteins; C493650:BRK1 protein, Arabidopsis; D018797:Cell Cycle Proteins; C505420:DIS3 protein, Arabidopsis; C118571:SPA1 protein, Arabidopsis; C455512:SPIKE1 protein, Arabidopsis; D051300:Wiskott-Aldrich Syndrome Protein Family; D000251:Adenosine Triphosphatases; C498859:NAP1 protein, Arabidopsis