MAP20, a microtubule-associated protein in the secondary cell walls of hybrid aspen, is a target of the cellulose synthesis inhibitor 2,6-dichlorobenzonitrile.
We have identified a gene, denoted PttMAP20, which is strongly up-regulated during secondary cell wall synthesis and tightly coregulated with the secondary wall-associated CESA genes in hybrid aspen (Populus tremula x tremuloides). Immunolocalization studies with affinity-purified antibodies specific for PttMAP20 revealed that the protein is found in all cell types in developing xylem and that it is most abundant in cells forming secondary cell walls. This PttMAP20 protein sequence contains a highly conserved TPX2 domain first identified in a microtubule-associated protein (MAP) in Xenopus laevis. Overexpression of PttMAP20 in Arabidopsis (Arabidopsis thaliana) leads to helical twisting of epidermal cells, frequently associated with MAPs. In addition, a PttMAP20-yellow fluorescent protein fusion protein expressed in tobacco (Nicotiana tabacum) leaves localizes to microtubules in leaf epidermal pavement cells. Recombinant PttMAP20 expressed in Escherichia coli also binds specifically to in vitro-assembled, taxol-stabilized bovine microtubules. Finally, the herbicide 2,6-dichlorobenzonitrile, which inhibits cellulose synthesis in plants, was found to bind specifically to PttMAP20. Together with the known function of cortical microtubules in orienting cellulose microfibrils, these observations suggest that PttMAP20 has a role in cellulose biosynthesis.
Rajangam
Alex S
AS
Swedish Center of Biomimetic Fiber Engineering, KTH-Royal Institute of Technology, AlbaNova, SE-10691 Stockholm, Sweden.
Kumar
Manoj
M
Aspeborg
Henrik
H
Guerriero
Gea
G
Arvestad
Lars
L
Pansri
Podjamas
P
Brown
Christian J-L
CJ
Hober
Sophia
S
Blomqvist
Kristina
K
Divne
Christina
C
Ezcurra
Ines
I
Mellerowicz
Ewa
E
Sundberg
Björn
B
Bulone
Vincent
V
Teeri
Tuula T
TT
D000595:Amino Acid Sequence; D001483:Base Sequence; D002473:Cell Wall / Q000187:drug effects* / Q000378:metabolism; D002482:Cellulose / Q000037:antagonists & inhibitors* / Q000097:blood; D017931:DNA Primers; D020869:Gene Expression Profiling; D006824:Hybridization, Genetic; D008869:Microtubule-Associated Proteins / Q000737:chemistry / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009570:Nitriles / Q000494:pharmacology*; D017386:Sequence Homology, Amino Acid; D014197:Trees / Q000378:metabolism*
D017931:DNA Primers; D008869:Microtubule-Associated Proteins; D009570:Nitriles; D002482:Cellulose; C055869:dichlobanil