title: Arabidopsis CAP1 - a key regulator of actin organisation and development.
abstract: Maintenance of F-actin turnover is essential for plant cell morphogenesis. Actin-binding protein mutants reveal that plants place emphasis on particular aspects of actin biochemistry distinct from animals and fungi. Here we show that mutants in CAP1, an A. thaliana member of the cyclase-associated protein family, display a phenotype that establishes CAP1 as a fundamental facilitator of actin dynamics over a wide range of plant tissues. Plants homozygous for cap1 alleles show a reduction in stature and morphogenetic disruption of multiple cell types. Pollen grains exhibit reduced germination efficiency, and cap1 pollen tubes and root hairs grow at a decreased rate and to a reduced length. Live cell imaging of growing root hairs reveals actin filament disruption and cytoplasmic disorganisation in the tip growth zone. Mutant cap1 alleles also show synthetic phenotypes when combined with mutants of the Arp2/3 complex pathway, which further suggests a contribution of CAP1 to in planta actin dynamics. In yeast, CAP interacts with adenylate cyclase in a Ras signalling cascade; but plants do not have Ras. Surprisingly, cap1 plants show disruption in plant signalling pathways required for co-ordinated organ expansion suggesting that plant CAP has evolved to attain plant-specific signalling functions.
authors.affiliation: The Integrative Cell Biology Laboratory, School of Biological and Biomedical Sciences, Durham University, South Road, Durham, DH1 3LE, UK.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Deeks
authors.forename: Cecília
authors.initials: C
authors.lastname: Rodrigues
authors.forename: Simon
authors.initials: S
authors.lastname: Dimmock
authors.forename: Tijs
authors.initials: T
authors.lastname: Ketelaar
authors.forename: Sutherland K
authors.initials: SK
authors.lastname: Maciver
authors.forename: Rui
authors.initials: R
authors.lastname: Malhó
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Hussey
mesh_terms: D008841:Actin Cytoskeleton / Q000235:genetics / Q000378:metabolism*; D000199:Actins / Q000378:metabolism; D017360:Arabidopsis / Q000166:cytology / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000235:genetics* / Q000378:metabolism*; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism; D003599:Cytoskeleton / Q000378:metabolism; D009024:Morphogenesis; D009154:Mutation; D018514:Plant Structures / Q000235:genetics / Q000254:growth & development; D011058:Pollen / Q000502:physiology
chemical_list: C475051:ATCAP1 protein, Arabidopsis; D000199:Actins; D029681:Arabidopsis Proteins; D018797:Cell Cycle Proteins; D003598:Cytoskeletal Proteins