Submitted to: Planta
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/11/2000
Publication Date: 6/1/2000
Citation: JOHNSTON, M.L., MIERNYK, J.A., RANDALL, D.D. IMPORT, PROCESSING, AND ASSEMBLY OF THE F- AND G-SUBUNITS OF CHLORPLAST PYRUVATE DEHYDROGENASE. PLANTA. 2000. V. 211(1). P. 72-76. Interpretive Summary: Respiration is the use of energy by living cells to do work. Both growth and reproduction are affected by respiration. As a result, respiration must be carefully controlled or wasted energy would decrease crop yields and reduce agricultural productivity. The control of respiration in plant cells is a subject of ongoing study. Two components of a protein that is important in the regulation of respiration were isolated from the model plant thale cress, and studied. Comparisons were made with a similar protein from animals and microbes in order to predict location within cells. A method was developed to test this prediction in the laboratory. This information will be important to researchers in their attempts to increase agricultural productivity by altering the control of plant cell respiration, and to other plant scientists who will try to design more efficient crop plants through either classical breeding or biotechnology.
Technical Abstract: Sequence comparisons were used to identify cDNAs potentially encoding the alpha- and beta-subunits of chloroplast pyruvate dehydrogenase. Coupled in vitro transcription plus translation was used to synthesize radiolabeled pyruvate dehydrogenase alpha and beta-subunit precursor proteins. When the precursors were incubated with intact pea (Pisum sativum L.) seedling chloroplasts in the presence of ATP, they were imported and proteolyticall processed. In contrast, there was no import or processing of the precursors by isolated, intact pea seedling mitochondria. Mono-specific antibodies to the recombinant pyruvate dehydrogenase alpha-subunit were additionally able to co-precipitate radiolabeled pyruvate dehydrogenase beta-subunit, indicating association between subunits after import and processing. Furthermore, size exclusion chromatography was used to identify an alpha-beta heterodimer that is intermediate in assembly of the native alpha2-beta2 heterotetrameric enzyme.