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Mechanism and Significance of Post-Translational Modifications in the Large (LS) and Small (SS) Subunits of Rubisco
Department of Horticulture
An enzyme has been discovered that has important implications for regulating gene expression in both animals and plants. Several important aspects of this enzyme can be capitalized on to improve photosynthetic efficiency in nearly all plant species, resulting in significant increases in food, fiber, and biomass production.
2009 Project Description
Collectively, co- and post-translational processing of proteins translated in the chloroplast form the final, biologically-active mature products from gene expression. Frequently these processes are unpredictable from protein primary sequence derived from DNA sequence, are often essential, and represent a collection of enzymes with evolved polypeptide substrate specificity and associated structural features that make them unique hybrids of their prokaryotic and eukaryotic counterparts.
Utilizing a collection of proven biochemical approaches and past accomplishments, this proposal provided structure/function relationships and in vivo functional significance for peptide deformylase (PDF), methionine aminopeptidase (MAP), and protein lysine methyltransferase (PKMT). Previous and existing biochemical and structural characterization of PDF and the PKMT, Rubisco LSMT, from this laboratory provided the rationale and justification for the approaches outlined in this proposal. Completion of the proposed studies provided unique structure/function relationships for co-and post-translational processing enzymes, and identification of polypeptide substrate specificity, and the mechanistic information that explains how they interact with all chloroplast-translated proteins.
The findings from these studies resulted in the development of new approaches for the control of weeds through the use of peptide deformylase inhibitors and the construction of transgenic plants resistant to those inhibitors. Others interested in chloroplast protein processing benefited from identification of the mechanism that determines the N-termini of chloroplast-translated proteins.
Whitney SM, Kane HJ, Houtz RL, & Sharwood RE (2009) Rubisco oligomers composed of linked small and large subunits assemble in tobacco plastids and have higher affinities for CO2 and O2. Plant Physiology,149(4):1887-1895.
Raunser, S., Magnani, R., Huang, Z., Houtz, R. L., Trievel, R. C., Penczek, P. A., and Walz, T. (2009). Rubisco in complex with Rubisco large subunit methyltransferase. PNAS , 106: 3160-3165.