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ARS Home » Research » Publications at this Location » Publication #121858
Title: ALTERED ATPASE ACTIVITY IN RUBISCO ACTIVASE AND GROWTH OF ARABIDOPSIS

Author
item EWY, ROBERT
item PORTIS JR, ARCHIE

Submitted to: Plant Physiology Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 6/2/2001
Publication Date: 6/2/2001
Citation: Ewy, R.G., Portis Jr, A.R. 2001. Altered atpase activity in rubisco activase and growth of arabidopsis. Plant Physiology Supplement: p.135.

Interpretive Summary:

Technical Abstract: Rubisco activase regulates the activity of Rubisco by removing inhibitors in a process dependent on ATP hydrolysis. Arabidopsis contains two isoforms of RA. The larger 46-kD isoform regulates RA activity via redox changes mediated by thioredoxin-f. These redox changes alter the sensitivity of RA to ATP/ADP. One important role for these changes may be to minimize ATP hydrolysis by the activase in the dark when Rubisco activity is not needed. Mutations of Q111 in the ATP-binding region of the smaller 43-kD recombinantly expressed isoform also alter the response of the ATPase activity to ATP/ADP. We have previously created lines of Arabidopsis containing only the 43-kD isoform and lines containing the mutations Q111D, Q111E, and Q111S in this smaller isoform of RA. In this study, we measure the levels of RA and the amount of above ground biomass in these lines and the wild type after 56 days of growth under low light (150 uEm**-2s**-1) with a 10/14hr-day/night cycle. Growth did not correlate with the amount of RA and the Q111S line produced more biomass than the wildtype, whereas the Q111D line produced the least. Rubisco activation state was higher in the 43-kD and all the Q111 mutant lines than in the wildtype line throughout a 24 hr time period. The relationships between growth, Rubisco activation, and the altered ATPase activities will be discussed.