Arabidopsis group Ie formins localize to specific cell membrane domains, interact with actin-binding proteins and cause defects in cell expansion upon aberrant expression.
The closely related proteins AtFH4 and AtFH8 represent the group Ie clade of Arabidopsis formin homologues. The subcellular localization of these proteins and their ability to affect the actin cytoskeleton were examined. AtFH4 protein activity was identified using fluorimetric techniques. Interactions between Arabidopsis profilin isoforms and AtFH4 were assayed in vitro and in vivo using pull-down assays and yeast-2-hybrid. The subcellular localization of group Ie formins was observed with indirect immunofluorescence (AtFH4) and an ethanol-inducible green fluorescent protein (GFP) fusion construct (AtFH8). AtFH4 protein affected actin dynamics in vitro, and yeast-2-hybrid assays suggested isoform-specific interactions with the actin-binding protein profilin in vivo. Indirect immunofluorescence showed that AtFH4 localized specifically to the cell membrane at borders between adjoining cells. Expression of an AtFH8 fusion protein resulted in GFP localization to cell membrane zones, similar to AtFH4. Furthermore, aberrant expression of AtFH8 resulted in the inhibition of root hair elongation. Taken together, these data suggest that the group Ie formins act with profilin to regulate actin polymerization at specific sites associated with the cell membrane.
Deeks
Michael J
MJ
The Integrative Cell Biology Laboratory, School of Biological and Biomedical Sciences, University of Durham, Science Laboratories, South Road, Durham DH1 3LE, UK.
Cvrcková
Fatima
F
Machesky
Laura M
LM
Mikitová
Veronika
V
Ketelaar
Tijs
T
Zársky
Viktor
V
Davies
Brendan
B
Hussey
Patrick J
PJ
D000199:Actins / Q000378:metabolism; D016960:Agrobacterium tumefaciens / Q000235:genetics; D000818:Animals; D029681:Arabidopsis Proteins / Q000235:genetics / Q000502:physiology*; D002462:Cell Membrane / Q000502:physiology*; D048429:Cell Size; D003001:Cloning, Molecular; D000080865:Formins; D018506:Gene Expression Regulation, Plant; D017930:Genes, Reporter; D007700:Kinetics; D051379:Mice; D008840:Microfilament Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*; D011994:Recombinant Proteins / Q000378:metabolism
D000199:Actins; D029681:Arabidopsis Proteins; C504538:FH8 protein, Arabidopsis; D000080865:Formins; D008840:Microfilament Proteins; D011994:Recombinant Proteins