Pectin activation of MAP kinase and gene expression is WAK2 dependent.
The angiosperm extracellular matrix, or cell wall, is composed of a complex array of cellulose, hemicellulose, pectins and proteins, the modification and regulated synthesis of which are essential for cell growth and division. The wall associated kinases (WAKs) are receptor-like proteins that have an extracellular domain that bind pectins, the more flexible portion of the extracellular matrix, and are required for cell expansion as they have a role in regulating cellular solute concentrations. We show here that both recombinant WAK1 and WAK2 bind pectin in vitro. In protoplasts pectins activate, in a WAK2-dependent fashion, the transcription of vacuolar invertase, and a wak2 mutant alters the normal pectin regulation of mitogen-activated protein kinases. Microarray analysis shows that WAK2 is required for the pectin activation of numerous genes in protoplasts, many of which are involved in cell wall biogenesis. Thus, WAK2 plays a major role in signaling a diverse array of cellular events in response to pectin in the extracellular matrix.
Kohorn
Bruce D
BD
Department of Biology, Bowdoin College, Brunswick, ME 04011, USA. bkohorn@bowdoin.edu
Johansen
Susan
S
Shishido
Akira
A
Todorova
Tanya
T
Martinez
Rhysly
R
Defeo
Elita
E
Obregon
Pablo
P
D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002473:Cell Wall / Q000378:metabolism; D005109:Extracellular Matrix / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D020411:Oligonucleotide Array Sequence Analysis; D010368:Pectins / Q000378:metabolism*; D011523:Protoplasts / Q000201:enzymology; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism
D029681:Arabidopsis Proteins; D008565:Membrane Proteins; D011994:Recombinant Proteins; D010368:Pectins; D020928:Mitogen-Activated Protein Kinases