The Role of ATP Molecules in Substrate Reduction by the Dark Operative Protochlorophyllide Oxidoreductase Enzyme during Chlorophyll Biosynthesis
Class
Article
Department
Chemistry and Biochemistry
Faculty Mentor
Edwin Antony
Presentation Type
Oral Presentation
Abstract
As the ultimate source of life-supporting energy, photosynthesis is fundamental to the perpetuation of all forms of life on earth. Photosynthesis involves the conversion of light energy from the sun into chemical energy stored in carbon derived molecules. The subsequent breakdown of these molecules provides the energy needed by the photosynthetic organism to sustain life. Non-photosynthetic organisms, in turn, receive their energy through the consumption of these photosynthetic organisms - thereby completing the cycle of life. Essential to photosynthesis is the pigment, chlorophyll, responsible for the capture and harnessing of light energy from the sun. One area of research in Dr. Antony's group looks at how chlorophyll pigments are made in photosynthetic cells. A 15 step biosynthetic pathway is required to makes chlorophyll. During this long process, the penultimate step is the conversion of a compound called protochlorophyllide into chlorophyllide through substrate reduction. This reduction step, which requires energy from the hydrolysis of ATP, is catalyzed by an enzyme called the Dark-Operative Protochlorophyllide oxidoreductase (DPOR). In the proposed research, special interest will be devoted to the mechanism of action of DPOR. My project will address two particular questions about this mechanism: Why are two ATP molecules required for each electron transfer event, and what happens when we remove one ATP from the reaction? To answer these questions, the following specific aims are proposed: Aim 1: Generate a heterodimeric L-protein with a single functional ATPase site that can be used to establish the precise role of each ATP molecule in electron transfer by the BchL protein. Aim 2: Using the heterodimeric L-protein carrying mutations in one or the other ATP binding site, I will test what happens to the DPOR substrate reduction mechanism by analyzing the chemical reaction wherein protochlorophyllide is reduced to chlorophyllide
Start Date
4-9-2015 3:00 PM
The Role of ATP Molecules in Substrate Reduction by the Dark Operative Protochlorophyllide Oxidoreductase Enzyme during Chlorophyll Biosynthesis
As the ultimate source of life-supporting energy, photosynthesis is fundamental to the perpetuation of all forms of life on earth. Photosynthesis involves the conversion of light energy from the sun into chemical energy stored in carbon derived molecules. The subsequent breakdown of these molecules provides the energy needed by the photosynthetic organism to sustain life. Non-photosynthetic organisms, in turn, receive their energy through the consumption of these photosynthetic organisms - thereby completing the cycle of life. Essential to photosynthesis is the pigment, chlorophyll, responsible for the capture and harnessing of light energy from the sun. One area of research in Dr. Antony's group looks at how chlorophyll pigments are made in photosynthetic cells. A 15 step biosynthetic pathway is required to makes chlorophyll. During this long process, the penultimate step is the conversion of a compound called protochlorophyllide into chlorophyllide through substrate reduction. This reduction step, which requires energy from the hydrolysis of ATP, is catalyzed by an enzyme called the Dark-Operative Protochlorophyllide oxidoreductase (DPOR). In the proposed research, special interest will be devoted to the mechanism of action of DPOR. My project will address two particular questions about this mechanism: Why are two ATP molecules required for each electron transfer event, and what happens when we remove one ATP from the reaction? To answer these questions, the following specific aims are proposed: Aim 1: Generate a heterodimeric L-protein with a single functional ATPase site that can be used to establish the precise role of each ATP molecule in electron transfer by the BchL protein. Aim 2: Using the heterodimeric L-protein carrying mutations in one or the other ATP binding site, I will test what happens to the DPOR substrate reduction mechanism by analyzing the chemical reaction wherein protochlorophyllide is reduced to chlorophyllide