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Photosynthetic Energy Transduction

We focus on understanding how the capture of solar energy in photosynthetic systems is converted to stored chemical products through various electron transfer processes and pathways in both cyanobacteria and algae.

four flask beakers containing green algae set in bins surrounded by light and attached to sensors, hoses, and valves

Full Publications List

An Illustration in three sections with an image of a quarter moon with an arrow indicating a movement to daylight (the sun) in the upper left and the label "Adaptation" in the center. The left section is labeled "Metabolic Pathways" and shows a blue bar with two green bars inside a large lighter green oval. There is a black line moving from one green bar to the other indicating an electron pathway; three black arrows out of the right green bar show H2, O2, and C (with a red X) coming out; there are lightning bolts hitting both green bars. The center section is labeled "Kinetics" and shows the same blue and green bars with lightning bolts and electron pathway, but electrons are shown going into the blue bar from "Carrier Pools" and are coming out of the right green bar. The right section is labeled "Mechanisms" and shows three black arrows indicating electrons coming out of the "Carrier Pools" from the center section and going into "Alternative Electron Flow" with a downward curved arrow pointing from "A" to "B" on the right.

Photosynthetic Electron Flow

Photosynthesis employs a number of electron flow pathways—including linear, cyclic, and alternative—toward specific generation of reduced compounds. We study the electron transfer events within and peripheral to the photosynthetic energy transduction (PET) chain in cyanobacteria and algae, as well as how those pathway components are coordinated both kinetically and structurally.

Illustration showing a series of eight blue arrows radiating outward in a circle from a central blue oval labeled "FDX" and one green arrow pointing into the oval, labeled "electrons from PSI". Moving counter clockwise, blue arrow 1 shows 2 electrons and points to an alpha-ketoglutarate synthase reaction; blue arrow 2 shows 2 electrons and points to an NADP Reductase (FNR) reaction; blue arrow 3 shows 6 electrons and points to a Nitrite Reductase reaction; blue arrow 4 shows 2 electrons and points to a Glutamate Synthase reaction; blue arrow 5 shows 2 electrons and points to a Hydrogenase reaction; blue arrow 6 shows 6 electrons and points to a Sulfite Reductase reaction; blue arrow 7 shows 2 electrons and points to a Xanthine Reductase reaction; and blue arrow 8 shows 2 electrons and points to a Thioredoxin Reductase reaction.

Energy Networks

We use a systems biology approach, incorporating metabolomics and fluxomics, to determine the constituents of energy networks (downstream of photosynthesis) that interact with photosynthetically generated reducing equivalents.

Illustration with a green sphere in the center; in the upper left is an icon of the sun. On the left side of the sphere are four black arrows of CO2 (pointing specifically to "Photosynthesis"), Glucose, Xylose, and Nitrogen, all pointing into the center of the large green sphere; the Nitrogen arrow has a red X through it. From "Photosynthesis" is a short black arrow with a red X through it pointing to "Glycogen" inside of the sphere. A long black arrow with a red X is pointing out of the sphere to the lower right corner and a small green sphere labeled "New Cells". Three black arrows area pointing out of the large green sphere at Acetate, AKG, and Pyruvate.

Energy Utilization

Photosynthetically fixed carbon is partitioned into numerous biosynthetic pathways. NREL studies the regulation of carbon partitioning using genetic, physiological, and spectroscopic techniques.
Illustration in three sections showing an image of a bright yellow sun in the left with a yellow beam radiating out from the sun and hitting the green liquid in a flask of the center image; a red squiggly line extends from the green liquid in the center flask to the right, which shows a black square with thin, light-colored horizontal bars with three thick red lines arranged on top in the pattern of two upside down L-shaped lines as mirror images with the third red line connecting the top of one L-shape to the bottom of the next L-shape.

Spectroscopy

Spectroscopic analyses of whole cells as well as isolated pathway components are performed to investigate electron transfer processes and mechanisms in the PET chain and with its interacting partners. These techniques support the studies of photosynthetic energy generation and utilization.

Research Team

Photo of a group of smiling men and women standing outside a building

Principal Investigators

Maria Lucia Ghirardi

Research Fellow

Maria.Ghirardi@nrel.gov | 303-384-6312

Paul King

Scientist VI — Supervisor, Photobiology Group

Paul.King@nrel.gov | 303-384-6277

Related and Integrated Programs

Algal Biofuels

Biohydrogen

Redox Biochemistry

Collaborators

Oklahoma State University (Dr. Rob Burnap)

University of Córdoba (Dr. David González Ballester)

Ohio State University (Dr. Patrice Hamel)

Pennsylvania State University (Dr. John Golbeck)

Photosynthetic Energy Transduction research at NREL is funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, and Biological and Environmental Research Programs, and the EERE Bioenergy Technologies Office.

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