Biological complexity:photosynthesis molecule (Introduction)

by David Turell , Friday, February 15, 2019, 19:45 (1894 days ago) @ David Turell

Another complex photosynthesis molecule's structure is outlined:

https://www.sciencedaily.com/releases/2019/02/190214174229.htm

Discovered decades ago, the protein complex targeted by the researchers, called NADH dehydrogenase-like complex (NDH), is known to help regulate the phase of photosynthesis where the energy of sunlight is captured and stored in two types of cellular energy molecules, which are later utilized to power the conversion of carbon dioxide into sugar. Past investigations revealed that NDH reshuffles the energized electrons moving among other protein complexes in the chloroplast in a way that ensures the correct ratio of each energy molecule is produced. Furthermore, NDH of cyanobacteria performs several additional roles including increasing the amount of carbon dioxide (CO2) available for sugar production by linking CO2 uptake with electron transfer.

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"Research on this enzyme has been difficult and experimental results confounding for the last 20 years or so because we have lacked complete information about the enzyme's structure," said Davies. "Knowing the structure is important for generating and testing out hypotheses of how the enzyme functions. The resolution we obtained for our structure of NDH has only really been achievable since the commercialization of the direct electron counting camera, developed in collaboration with Berkeley Lab."

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In the current study, first author Thomas Laughlin, a UC Berkeley graduate student with a joint appointment at MBIB, isolated NDH complexes from membranes of a photosynthetic cyanobacterium provided by the Junko Yano and Vittal Yachandra Lab in MBIB and imaged them using a state-of-the-art cryo-TEM instrument fitted with the latest direct electron detector. Located on the UC Berkeley campus, the cryo-TEM facility is managed by the Bay Area CryoEM consortium, which is partly funded by Berkeley Lab.

The resulting atom density map was then used to build a model of NDH that shows the arrangement of all the protein subunits of NDH and the most likely position of all the atoms in the complex. By examining this model, Davies' team will be able to formulate and then test hypotheses of how NDH facilitates sugar production by balancing the ratio of the two cellular energy molecules.

"While the structure of NDH alone certainly addresses many questions, I think it has raised several more that we had not even thought to consider before," said Laughlin.

Comment: Be sure to look at this monster molecule which is an enzyme. The preceding entry here was of a different giant molecule which is part of the photosynthesis process. (December 21, 2018, 22:24) It was 'complex 1' which uses iron in its processing role. There is no way such a complex biological process arrived by chance, considering the size of these molecules and their complexity, which is so difficult for scientists to figure them out.