Arabidopsis CROOKED encodes for the smallest subunit of the ARP2/3 complex and controls cell shape by region specific fine F-actin formation.
The generation of a specific cell shape requires differential growth, whereby specific regions of the cell expand more relative to others. The Arabidopsis crooked mutant exhibits aberrant cell shapes that develop because of mis-directed expansion, especially during a rapid growth phase. GFP-aided visualization of the F-actin cytoskeleton and the behavior of subcellular organelles in different cell-types in crooked and wild-type Arabidopsis revealed that localized expansion is promoted in cellular regions with fine F-actin arrays but is restricted in areas that maintain dense F-actin. This suggested that a spatiotemporal distinction between fine versus dense F-actin in a growing cell could determine the final shape of the cell. CROOKED was molecularly identified as the plant homolog of ARPC5, the smallest sub-unit of the ARP2/3 complex that in other organisms is renowned for its role in creating dendritic arrays of fine F-actin. Rescue of crooked phenotype by the human ortholog provides the first molecular evidence for the presence and functional conservation of the complex in higher plants. Our cell-biological and molecular characterization of CROOKED suggests a general actin-based mechanism for regulating differential growth and generating cell shape diversity.
Mathur
Jaideep
J
Botanical Institute III, University of Köln, Gyrhofstrasse 15, Köln, D-50931, Germany. jaideep.mathur@uni-koeln.de
Mathur
Neeta
N
Kirik
Victor
V
Kernebeck
Birgit
B
Srinivas
Bhylahalli Purushottam
BP
Hülskamp
Martin
M
D051377:Actin-Related Protein 2; D051376:Actin-Related Protein 2-3 Complex; D051378:Actin-Related Protein 3; D000199:Actins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics; D029681:Arabidopsis Proteins / Q000235:genetics*; D003593:Cytoplasm / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000235:genetics*; D004247:DNA / Q000378:metabolism; D017343:Genes, Plant; D006056:Golgi Apparatus / Q000378:metabolism; D049452:Green Fluorescent Proteins; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008164:Luminescent Proteins / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D010641:Phenotype; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D016608:Talin / Q000737:chemistry
C495928:ACTR3 protein, human; C512742:ARP2 protein, Arabidopsis; D051377:Actin-Related Protein 2; D051376:Actin-Related Protein 2-3 Complex; D051378:Actin-Related Protein 3; D000199:Actins; D029681:Arabidopsis Proteins; D003598:Cytoskeletal Proteins; D008164:Luminescent Proteins; D011993:Recombinant Fusion Proteins; D016608:Talin; D049452:Green Fluorescent Proteins; D004247:DNA