In vivo and in vitro activation of temperature-responsive plant map kinases.
Alfalfa cells possess two temperature-responsive Mitogen-Activated Protein Kinases (MAPKs), SAMK (Stress-Activated MAP Kinase) activated at 4 degrees C and HAMK (Heat shock-Activated MAP Kinase) activated at 37 degrees C. Both are inactive at 25 degrees C. We show here that SAMK is activated when cells are transferred from 37 degrees C to 25 degrees C, and HAMK is activated when cells are transferred from 4 degrees C to 25 degrees C. Moreover, we show that heat activation of HAMK also occurs in cell-free extracts. We conclude that (i) SAMK or HAMK activation does not require a particular temperature but a relative temperature shift, and (ii) that either HAMK itself or one or more of its upstream activators can sense temperature change directly.
Sangwan
Veena
V
Department of Biology, McGill University, 1205 Avenue Docteur Penfield, H3A 1B1, Montreal, QC, Canada.
Dhindsa
Rajinder S
RS
D002474:Cell-Free System; D003080:Cold Temperature; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation; D006358:Hot Temperature; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D010944:Plants / Q000201:enzymology*
D020928:Mitogen-Activated Protein Kinases