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Title: RECOMBINANT RUBISCO ACTIVASE PROTEINS ALTERED AT AN ATP BINDING SITE EXHIBIT DIFFERENT SENSITIVITIES TO ELEVATED TEMPERATURE

Author
item EWY, ROBERT
item PORTIS JR, ARCHIE

Submitted to: Plant Physiology Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 7/1/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Rubisco Activase in Arabidopsis is present as 42- and 46-kD polypeptides and the presence of the two forms may play a role in the response of photosynthesis to temperature. As part of our efforts to determine whether transgenic plants which contain one of these two mutant forms have altered heat responses, we have further characterized the recombinant 42-kD Q111D and Q111E mutants in vitro with respect to their heat stability in the presence of the nucleotides ADP and ATP-gamma-S, an ATP analogue. Enzymes were pre-incubated with either ADP or ATP-gamma-S, at selected temperatures and then assayed for ATPase activity. The Q111E was considerably more heat stable than the Q111D mutant in the presence of 2 mM ADP. The presence of ATP-gamma-S increased the heat stability of both the Q111D and Q111E forms of the enzyme relative to ADP. The significance of the observed differences in heat sensitivity with respect to the potential to alter the heat sensitivity of transgenic plants will be discussed. This research was supported, in part by DOE grant 97ER20268.