Two members of the thioredoxin-h family interact with the kinase domain of a Brassica S locus receptor kinase.
To determine potential targets of the S locus receptor kinase (SRK) during the Brassica self-incompatibility response, a yeast two-hybrid library was screened with the SRK-910 protein kinase domain. Two thioredoxin-h-like clones, THL-1 and THL-2, were found to interact specifically with the SRK-910 protein kinase domain and not to interact with the protein kinase domains from the Arabidopsis receptor-like protein kinases (RLK) RLK4 and RLK5. The interaction between THL-1 and the SRK-910 protein kinase domain was confirmed using coimmunoprecipitation experiments with fusion proteins produced in Escherichia coli. THL-1 has thioredoxin activity based on an insulin reduction assay, and THL-1 is weakly phosphorylated by the SRK-910 protein kinase domain. THL-1 and THL-2 are both expressed in a variety of tissues but show some differences in steady state mRNA levels, with THL-2 being preferentially expressed in floral tissues. This indicates a more general biological function for these thioredoxins in addition to a potential role as effector molecules in the self-incompatibility signal cascade.
Bower
M S
MS
Biology Department, York University, Ontario, Canada.
Matias
D D
DD
Fernandes-Carvalho
E
E
Mazzurco
M
M
Gu
T
T
Rothstein
S J
SJ
Goring
D R
DR
D000595:Amino Acid Sequence; D001665:Binding Sites / Q000235:genetics; D001937:Brassica / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D008969:Molecular Sequence Data; D010766:Phosphorylation; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D013879:Thioredoxins / Q000235:genetics / Q000378:metabolism*
D010940:Plant Proteins; D013879:Thioredoxins; D011494:Protein Kinases; C079832:S-receptor kinase