An international research team has solved the structure and explained the
function of photosynthetic complex I, the membrane protein complex which
plays a major role in dynamically rewiring photosynthesis.

In plant cells, complex I is used in two places: one is in mitochondria, the
cell's power plants, the other is in chloroplasts, where photosynthesis
occurs. In both instances, it forms part of an electron transport chain,
which can be thought of as biology's electrical circuit. These are used to
drive the cells' molecular machines responsible for energy production and
storage.

The researchers showed that the molecular structure of photosynthetic
complex I differs considerably from its respiratory relative. In particular,
the part responsible for electron transport has a different structure, since
it is optimized for cyclic electron transport in photosynthesis. In the next
step, the team analyzed the structural elements responsible for the
efficient interaction of complex I and the protein ferredoxin. They found
that complex I has a particularly flexible part in its structure, which
captures the protein ferredoxin like a fishing rod. This allows ferredoxin
to reach the optimal binding position for electron transfer.

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