Purdue Biologists' Spotlight Solves Mysteries Of Photosynthesis, Metabolism | |
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Using advanced imaging techniques, a team of Purdue biologists has determined the structure of the cytochrome, a protein complex that governs photosynthesis in a blue-green bacterium. While their work does not immediately suggest any industrial applications, it does reveal a wealth of information not only about a chemical process crucial to all life on the planet, but also about how cells handle and distribute energy. According to team member William Cramer, the study is a great leap forward in our understanding of photosynthesis.
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"Where we once could see merely the tip of the iceberg, we can now perceive the entire mechanism of photosynthesis," говорит Cramer, из Henry Koffler Distinguished Professor of Biological Sciences in Purdue's School of Science. "Before we found a way to crystallize the cytochrome, we had a general picture of the photosynthetic process, but possessed only a fraction of a percent of the information we now have. Now that we can examine these proteins closely with X-ray crystallography, it could lead to knowledge about how all cells exchange energy with their environment."
Cramer также сообщил, что исследование является важным вкладом в область исследований по протеомике, т.к. мало данных о роли семейства белков, вставленных в мембраны.
"Membrane proteins are involved in a cell's interactions with its environment, making them an essential component of metabolism," he said. "However, they are difficult to crystallize for study. This research could clarify our understanding of energy flow in human cells as well, giving us better insight into respiration and the absorption of antioxidants in animal cells."
Сообщение появилось (Thursday, 10/2) в Science's online edition, Science Express. Первые два автора манускрипта - Genji Kurisu, посетивший студентов Osaka University, Japan, и Huamin Zhang, associate research scientist из Department of Biological Sciences at Purdue, внесли основной вклад в кристаллографическую и биохимическую часть анализа.
В соотщении рисуется сложная картина перемещений электронов и протонов поперек клеточной мембраны бактерий, границы между клетокой и ее окружением.
"Plant cell membranes are like the two ends of a battery," говорит Janet Smith, проф. биол. наук и член группы, ответственной за большую часть структурного анализа. "They are positive on the inside and negative on the outside, and they are charged up when solar energy excites electrons from hydrogen within the cell. The electrons travel up into the cell membrane via proteins that conduct them just like wires. Of course, because of their high energy level, the electrons want to 'fall back' like water over a dam, releasing the energy a plant harnesses to stay alive."
Эта общая картина в основном известна ученым, а сложные перемещения электронов и протонов в мембране нет.
"It's a bit like watching electrons move through a computer chip," поясняет Smith. "A microprocessor has far more complex and numerous routes for its electricity to follow than, say, a flashlight, which only has one. But while a chip uses electrons to flip tiny digital switches back and forth for calculations, the membrane uses them to drive the cell's metabolism."
Для исследования были использованы клетки cyanobacterium, одноклеточные термофильные растения широко распространённые в горячих источниках, таких как в Yellowstone. Определенные cyanobacterium, использованные в этом исследовании, были выделены швейцарскими учеными из грорячих источникой Исландии.
Т.к. животные не обладают фотосинтезом, то их клетки м.б. использовать сходные белки для дыхания. Сходство м. привести к тому, что будет лучше понят наши собственные метаболические процессы.
"What we see when we examine these proteins is the nature of their partial similarity," говорит Cramer. "The differences can now be explored more easily."
Изучение мембранных белков само по себе является важной задачей для исследователей, занимающихся кристаллизацией белков. Мембранные белки трудны для изучения, тк. они не расстворяются в воде, что является критической ступенью в процессе кристаллизации.
"This difficulty has left a gap in our knowledge of membrane proteins, which total about 30 percent of the proteins in living things," Cramer said. "After finding a way to crystallize a membrane protein earlier this year, it only took a few months before we were able to look at photosynthesis in such detail."
Группа надеется, что их метод м.б. приложим и к др. мембранным белкам, который, как они полагают, обладает несколькими из обширного неизведанного потенциала.
"If cells were countries, membrane proteins would control all the international commerce," говорит Cramer. "They are the border guards that regulate all the energy transfer and material exchange across the boundary between the cell and its environment. If you want to get a drug into a cell where it can be of use, you have to deal with the membrane proteins - that's why they're so tempting a subject to study."
Работы частично субсдированы National Institute of General Medical Sciences (NIGMS), отделением National Institutes of Health. NIGMS's Dr. Peter Preusch полагает, что Cramer's достижения по исследованию мембранных булков приведут к важным открытиям.
"New insights provided by Dr. Cramer's elegant studies underscore the value of searching for biological secrets in model systems," he said. "The findings will advance the study of energy metabolism in humans."
Члены группы сотрудничали с несколкми центрами в Purdue, включая Markey Center for Structural Biology, the Bindley Bioscience Center at Discovery Park, the Interdepartmental Program in Biochemistry and Molecular Biology, and the Purdue Cancer Center.
Writer: Chad Boutin, (765) 494-2081, cboutin@purdue.edu
Sources: William Cramer, (765) 494-4956, wac@bilbo.bio.purdue.edu
Janet Smith, (765) 494-9246, jsmith@purdue.edu
Purdue News Service: (765) 494-2096; purduenews@purdue.edu
Source: Purdue University |