Psb28 regulating optical system II assembly and repair structure basic identification

Psb28 regulating optical system II assembly and repair structure basic identification

Psb28-regulated photosystem II assembly and repair structure basic identification Psb28-regulated photosystem II assembly and repair structure foundation identification

A few days ago, the photosynthetic membrane protein structural biology research team of the Institute of Botany, Chinese Academy of Sciences and the team of Sui Senfang, an academician of the Chinese Academy of Sciences and professor of Tsinghua University, used single-particle cryo-electron microscopy to analyze the thermophilic cyanobacteria photosystem II (PSII) intermediate complex Psb28- The near-atomic resolution (3.
14Å) three-dimensional structure of RC47 and Psb28-PSII reveals the precise binding site of Psb28 and the structural characteristics of the complex
.

Related research was published in "Nature-Plants" on July 5

PSII is an important membrane protein machine located on the thylakoid membrane of oxygen-emitting photosynthetic organisms.
It uses light energy to split water into protons and electrons and release oxygen
.

The PSII core complex with photosynthetic oxygen evolution function is composed of 20 protein subunits (17 transmembrane proteins and 3 peripheral proteins), manganese clusters, non-heme iron, pigments, and plastoquinone (QA and QB) molecules Pigment membrane protein complex composed of multiple cofactors

The assembly of PSII in the body and the repair after being damaged by light are regulated by a variety of assembly factors, which are complex and highly ordered processes completed by the formation of different intermediate complexes
.

Psb28 is one of the assembly factors of PSII.

This time, the researchers found that the Psb28-RC47 complex contains 14 protein subunits, including 3 core large subunits (D1, D2, CP47), 11 small subunits (PsbE, PsbF, PsbH, PsbI, PsbL, PsbM) , PsbT, PsbX, Psb28, Tsl0063 and an unknown transmembrane protein UTP); The Psb28-PSII complex has 4 more transmembrane subunits (CP43, PsbK, Psb30 and PsbZ) than the RC47 complex
.

The study further found that Psb28 is located on the matrix side of PSII and binds to D1, D2 and CP47; Tsl0063 is a transmembrane helix protein that interacts with D1, CP47, PsbH and PsbL, and is essential for maintaining the structure of PSII core subunits and the binding of Psb28 Has an important role
.

The UTP is located on the outside of Tsl0063 and is arranged in an X shape with Tsl0063
.

Compared with the structure of PSII with oxygen releasing function, the C-terminal of CP47, the DE loop of D1 and the DE loop of D2 have changed significantly, leading to the conformation of QA, QB and non-heme iron binding sites and the surrounding coordination environment And the changes in the hydrogen bond network; in addition, the study also further revealed the structural characteristics of the binding site in the absence of manganese clusters

Researchers believe that the conformational changes induced by Psb28 and Tsl0063 may help protect immature PSII from light damage
.

Based on structural information, they further proposed a model in which Psb28 participates in the regulation of PSII assembly and repair, which is of great significance for understanding PSII assembly and repair and its regulatory mechanism

Sui Senfang and Han Guangye, a researcher from the Institute of Botany, are the co-corresponding authors of the paper
.

Kuang Tingyun, a member of the Chinese Academy of Sciences, and Wang Wenda, a researcher from the Institute of Botany, Chinese Academy of Sciences, participated in the research

Related paper information: https://doi.

https://doi.
org/10.
1038/s41477-021-00961-7