Submitted to: Physiologia Plantarum
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/29/2000
Publication Date: 8/1/2001
Citation: Broz, A.K., Thelen, J.J., Muszynski, M.G., Miernyk, J.A., Randall, D.D. 2001. Zmpp2, a novel type-2c protein phosphatase from maize. Physiologia Plantarum. V.52(361):1739-1740. 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. A protein that might be important in the regulation of respiration was isolated from corn 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: A cDNA clone was selected as a candidate for the catalytic subunit of phospho-pyruvate dehydrogenase-phosphatase by screening a maize (Zea mays) expressed sequence tag database with the bovine pyruvate dehydrogenase phosphatase deduced amino acid sequence. Both strands of the cDNA were completely sequenced. The maize clone contains an open reading frame of 1098 base pairs that encodes a polypeptide of 40,127 Da, ZMPP2. The deduced amino acid sequence of ZMPP2 is related to the PP2C class of protein phosphatases, as is PDP. However, the expression pattern of ZMPP2, determined by reverse transcriptase-polymerase chain reaction, was different from those of the maize pyruvate dehydrogenase E1alpha subunit and pyruvate dehydrogenase kinase. Additionally, the subcellular location of ZMPP2 was predicted as cytoplasmic using a computer localization algorithm, while the pyruvate dehydrogenase complex regulated by reversible ephosphorylation is mitochondrial. Thus, ZMPP2 is a PP2C-type protein phosphatase related to but distinct from pyruvate dehydrogenase phosphatase.