Mechanism of substrate reduction by the Dark-operative Protochlorophyllide Oxidoreductase (DPOR) complex
Class
Article
Department
Chemistry and Biochemistry
Faculty Mentor
Edwin Antony
Presentation Type
Poster Presentation
Abstract
Photosynthesis is a fundamental biological process that sustains life on earth. Chlorophyll is the pigment that captures sunlight and converts it to chemical energy through photosynthesis. These essential light-harvesting compounds are found in photosynthetic plants, cyanobacteria, green algae, angiosperms and gymnosperms. In the chlorophyll biosynthetic pathway, protochlorophyllide (Pchlide) serves as the precursor molecule for chlorophyll. Protochlorophyllide oxidoreductases are a class of enzymes that catalyze the conversion of Pchlide to chlorophyllide a (Chlide), which subsequently is reduced and modified to form chlorophyll. A light-dependent protochlorophyllide oxidoreductase (LPOR) is found in flowering plants (angiosperms), and as the name suggests, requires the energy from light to catalyze the conversion. An unrelated dark-operative light-independent version (DPOR - dark-operative protochlorophyllide oxidoreductase) is found in cyanobacteria, photosynthetic bacteria, green algae and gymnosperms. DPOR functions in the absence of light, or low-light conditions and in the absence of oxygen. DPOR is a multi-subunit complex consisting of the BchL, BchN and BchB proteins which share striking structural similarities to the Nif proteins in the Nitrogenase complex. As a result, questions arise with respect to the catalytic mechanism of Pchlide reduction. If the two proteins share similar structural features and subunit architecture, do the two systems function similarly with respect to substrate reduction? Initial data indicate mechanistic similarities, and subtle differences that are summarized in our findings.
Start Date
4-9-2015 1:30 PM
Mechanism of substrate reduction by the Dark-operative Protochlorophyllide Oxidoreductase (DPOR) complex
Photosynthesis is a fundamental biological process that sustains life on earth. Chlorophyll is the pigment that captures sunlight and converts it to chemical energy through photosynthesis. These essential light-harvesting compounds are found in photosynthetic plants, cyanobacteria, green algae, angiosperms and gymnosperms. In the chlorophyll biosynthetic pathway, protochlorophyllide (Pchlide) serves as the precursor molecule for chlorophyll. Protochlorophyllide oxidoreductases are a class of enzymes that catalyze the conversion of Pchlide to chlorophyllide a (Chlide), which subsequently is reduced and modified to form chlorophyll. A light-dependent protochlorophyllide oxidoreductase (LPOR) is found in flowering plants (angiosperms), and as the name suggests, requires the energy from light to catalyze the conversion. An unrelated dark-operative light-independent version (DPOR - dark-operative protochlorophyllide oxidoreductase) is found in cyanobacteria, photosynthetic bacteria, green algae and gymnosperms. DPOR functions in the absence of light, or low-light conditions and in the absence of oxygen. DPOR is a multi-subunit complex consisting of the BchL, BchN and BchB proteins which share striking structural similarities to the Nif proteins in the Nitrogenase complex. As a result, questions arise with respect to the catalytic mechanism of Pchlide reduction. If the two proteins share similar structural features and subunit architecture, do the two systems function similarly with respect to substrate reduction? Initial data indicate mechanistic similarities, and subtle differences that are summarized in our findings.