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Cryo-EM structure of a functional monomeric Photosystem I from Thermosynechococcus elongatus reveals red chlorophyll cluster.

ABSTRACT: A high-resolution structure of trimeric cyanobacterial Photosystem I (PSI) from Thermosynechococcus elongatus was reported as the first atomic model of PSI almost 20 years ago. However, the monomeric PSI structure has not yet been reported despite long-standing interest in its structure and extensive spectroscopic characterization of the loss of red chlorophylls upon monomerization. Here, we describe the structure of monomeric PSI from Thermosynechococcus elongatus BP-1. Comparison with the trimer structure gave detailed insights into monomerization-induced changes in both the central trimerization domain and the peripheral regions of the complex. Monomerization-induced loss of red chlorophylls is assigned to a cluster of chlorophylls adjacent to PsaX. Based on our findings, we propose a role of PsaX in the stabilization of red chlorophylls and that lipids of the surrounding membrane present a major source of thermal energy for uphill excitation energy transfer from red chlorophylls to P700.

SUBMITTER: Coruh O

PROVIDER: S-EPMC7940658 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Crystal structure of monomeric photosystem II from Thermosynechococcus elongatus at 3.6-a resolution.

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3.2 Å resolution structure of a functional monomeric Photosystem I from Thermosynechococcus elongatus BP-1 by single particle cryo-EM with a 200 kV CRYO ARM electron microscope

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| S-EPMC7985191 | biostudies-literature

Variation of exciton-vibrational coupling in photosystem II core complexes from Thermosynechococcus elongatus as revealed by single-molecule spectroscopy.

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