Structure and assembly mechanism of plant C<sub>2</sub>S<sub>2</sub>M<sub>2</sub>-type PSII-LHCII supercomplex.
basic_science · Level V
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- Record sourced from PubMed, PMID 28839073.
- Also identified by DOI 10.1126/science.aan0327.
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Abstract
In plants, the photosynthetic machinery photosystem II (PSII) consists of a core complex associated with variable numbers of light-harvesting complexes II (LHCIIs). The supercomplex, comprising a dimeric core and two strongly bound and two moderately bound LHCIIs (C<sub>2</sub>S<sub>2</sub>M<sub>2</sub>), is the dominant form in plants acclimated to limited light. Here we report cryo-electron microscopy structures of two forms of C<sub>2</sub>S<sub>2</sub>M<sub>2</sub> (termed stacked and unstacked) from <i>Pisum sativum</i> at 2.7- and 3.2-angstrom resolution, respectively. In each C<sub>2</sub>S<sub>2</sub>M<sub>2</sub>, the moderately bound LHCII assembles specifically with a peripheral antenna complex CP24-CP29 heterodimer and the strongly bound LHCII, to establish a pigment network that facilitates light harvesting at the periphery and energy transfer into the core. The high mobility of peripheral antennae, including the moderately bound LHCII and CP24, provides insights into functional regulation of plant PSII.
Medical subject headings
- Light-Harvesting Protein Complexes
- Pisum sativum
- Photosynthesis
- Photosystem II Protein Complex
- Protein Kinases