Arabidopsis profilin isoforms, PRF1 and PRF2 show distinctive binding activities and subcellular distributions.
Profilin is an actin-binding protein that shows complex effects on the dynamics of the actin cytoskeleton. There are five profilin isoforms in Arabidopsis thaliana L. However, it is still an open question whether these isoforms are functionally different. In the present study, two profilin isoforms from Arabidopsis, PRF1 and PRF2 were fused with green fluorescent protein (GFP) tag and expressed in Escherichia coli and A. thaliana in order to compare their biochemical properties in vitro and their cellular distributions in vivo. Biochemical analysis revealed that fusion proteins of GFP-PRF1 and GFP-PRF2 can bind to poly-L-proline and G-actin showing remarkable differences. GFP-PRF1 has much higher affinities for both poly-L-proline and G-actin compared with GFP-PRF2. Observations of living cells in stable transgenic A. thaliana lines revealed that 35S::GFP-PRF1 formed a filamentous network, while 35S::GFP-PRF2 formed polygonal meshes. Results from the treatment with latrunculin A and a subsequent recovery experiment indicated that filamentous alignment of GFP-PRF1 was likely associated with actin filaments. However, GFP-PRF2 localized to polygonal meshes resembling the endoplasmic reticulum. Our results provide evidence that Arabidopsis profilin isoforms PRF1 and PRF2 have different biochemical affinities for poly-L-proline and G-actin, and show distinctive localizations in living cells. These data suggest that PRF1 and PRF2 are functionally different isoforms.
Wang
Feng
F
State Key Laboratory of Plant Physiology and Biochemistry, China Agricultural University, Beijing 100094, China.
Jing
Yanping
Y
Wang
Zhen
Z
Mao
Tonglin
T
Samaj
Jozef
J
Yuan
Ming
M
Ren
Haiyun
H
D000199:Actins / Q000378:metabolism*; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D019086:Bridged Bicyclo Compounds, Heterocyclic; D004721:Endoplasmic Reticulum / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000378:metabolism; D010455:Peptides / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D051304:Profilins / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D020033:Protein Isoforms / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D053778:Thiazolidines
D000199:Actins; D029681:Arabidopsis Proteins; D019086:Bridged Bicyclo Compounds, Heterocyclic; C495746:PRF1 protein, Arabidopsis; C495747:PRF2 protein, Arabidopsis; D010455:Peptides; D051304:Profilins; D020033:Protein Isoforms; D011993:Recombinant Fusion Proteins; D053778:Thiazolidines; D049452:Green Fluorescent Proteins; C011083:polyproline; C037067:latrunculin A