Role of posttranslational modifications in controlling the specificity of response regulation

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The information encoded in the genes of an organism is ultimately decoded as proteins, which by acting as key enzymes, building blocks of a cell, transporters, or receptors, perform almost all cellular functions. Proteins are made of a permutation of 20 distinct amino acids, the sequence of which is determined by the nucleotide sequence of genes. Most of these amino acids can be covalently modified after their translation, resulting in multiple, unique proteoforms of a single protein with distinct function. The post-translational modifications (PTMs) are thus nature’s way of amplifying the information encoded in the genome to provide dynamic, flexible and potentially reversible mechanisms for regulating an organism’s development, physiology and survival. For multi-functional proteins, specific PTMs may associate with explicit protein function. Therefore, comprehensive interpretation of the ‘PTM code’ of an organism is critical to understand the gene to function link. Successful completion of this research will not only fill major gaps in our knowledge of how context-specific PTMs dictate the roles of a protein in regulation of distinct responses, but will also add significantly to elucidation of plant signaling mechanisms, which affect key agronomical traits. Therefore, in addition to advancing our fundamental understanding of a complex biological concept, this research will also apply broadly to the problems that plague our world today: generating higher yield with limited resources and unfavorable environments. The work will also involve the training of a technician, a postdoctoral scientist in a multidisciplinary field and mentoring of undergraduate students. The research will help promote an understanding of plant science to the high school students and general public via a series of hands on experiments and interactive presentations. This project aims to determine the existence of multiple, context-dependent proteoforms of a single protein, the Arabidopsis heterotrimeric Gα protein (GPA1) critical to G-protein signaling, and connect them to specific GPA1-regulated functions. Comprehensive interpretation of the post-translational modification-dependent ‘protein code’ of an organism is critical to understand the genotype to phenotype link. This research addresses some of the most fundamental questions related to the roles of PTMs such as (i) how specific PTMs affect the core properties of a protein, (ii) what are the organism-level, context-specific effects of PTMs of a protein, and (iii) how this specificity is achieved. Successful completion of this research will not only fill major gaps in our knowledge of regulatory roles of protein PTMs, but will also generate a knowledge base suitable for other plants (and metazoans), where similar analyses are not possible due to complexity of the system. It will also help fine-tune the plant G-protein signaling mechanisms of agricultural relevance because naturally occurring or engineered changes in G-proteins have profound effects on plant architecture, stress responses and yield.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.