Evolution of the mechanism of peptidylglycine-alpha-amidating monooxygenase

Johns Hopkins University, Baltimore MD

Investigators

Abstract

Title: Evolution of the mechanism of peptidylglycine-alpha-amidating monooxygenase Peptides are very small proteins made up of short and precise sequences of amino acid building blocks. Many peptides serve as signaling agents such as hormones and neurotransmitters in complex multicellular organisms. After synthesis many of these signaling peptides require further modification for activation. In this project, the investigator will study the enzymes needed for a specific peptide modification from several distantly related organisms. The goal of the research is to identify different structural and chemical changes across the different organisms that resulted in the gain or the loss of different features of the enzyme. Determination of the mechanism of this important step in the modification of peptide signaling molecules and how the mechanism changes in different organisms will guide the development of new ways of producing synthetic modified peptides. The work will also lead to a better understanding of how different enzyme structures can give rise to improved efficiency or specificity for a chemical reaction. The laboratory of the PI will continue its efforts to bring the excitement of science to high school and undergraduate students with emphasis on including underrepresented minorities in the research programs and STEM education. Communication between different parts of an organism via secreted peptides is a widely distributed biological signaling mechanism. Many of these peptides require amidation at their carboxy terminus for full-activity. Such peptides are expressed as precursors that, after processing, contain a glycine residue as their last residue. Oxidative cleavage of the glycine N-C(alpha) bond produces a des-glycine amidated peptide and glyoxylate. Only one enzyme in the complete phylogenetic spectrum is known to catalyze this reaction: the bi-functional peptidylglycine-alpha-amidating monooxygenase. The reaction takes place in two stages, the hydroxylation of the glycine C(alpha) by peptidyl-glycine-alpha-hydroxylating monooxygenase, and cleavage of the N-C(alpha) bond by peptidylglycine-alpha-amidating lyase. This project will study the peptidylglycine-alpha-amidating monooxygenases from several distantly related organisms with the goal of determining when in evolution they appeared, while trying to identify the structural and chemical changes that resulted in the gain or the loss of different features of the enzyme not critical for the chemical reaction. Structural and biochemical information obtained by X-ray diffraction, small angle scattering and kinetic measurements of the proteins from evolutionarily distant organisms will be used in this work.