The low molecular mass subunits of the photosynthetic supracomplex, photosystem II

• The photosystem II (PSII) complex is located in the thylakoid membrane of higher plants, algae and cyanobacteria and drives the water oxidation process of photosynthesis, which splits water into reducing equivalents and molecular oxygen by solar energy. Electron and X-ray crystallography analyses have revealed that the PSII core complex contains between 34 and 36 transmembrane α-helices, depending on the organism. Of these helices at least 12-14 are attributed to low molecular mass proteins. However, to date, at least 18 low molecular mass (<10 kDa) subunits are putatively associated with the PSII complex. Most of them contain a single transmembrane span and their protein sequences are conserved among photosynthetic organisms. In addition, these proteins do not have any similarity to any known functional proteins in any type of organism, and only two of them bind a cofactor. These findings raise intriguing questions about why there are so many small protein subunits with single-transmembrane spans in the PSII complex, and their possible functions. This article reviews our current knowledge of this group of proteins. Deletion mutations of the low molecular mass subunits from both prokaryotic and eukaryotic model systems are compared in an attempt to understand the function of these proteins. From these comparisons it seems that the majority of them are involved in stabilization, assembly or dimerization of the PSII complex. The small proteins may facilitate fast dynamic conformational changes that the PSII complex needs to perform an optimal photosynthetic activity.

Ämnesord

NATURVETENSKAP  -- Biologi -- Biokemi och molekylärbiologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Biochemistry and Molecular Biology (hsv//eng)

Nyckelord

Arabidopsis

Function

PS2

Small protein

Synechocystis

cytochrome b559

membrane protein

protein

protein psbe

protein psbh

protein psbi

protein PsbJ

protein psbk

protein PsbL

protein psbm

protein psbn

protein psbr

protein psbtc

protein psbtn

protein psbw

protein psbx

protein psby

protein psbz

protein subunit

unclassified drug

binding affinity

chloroplast

comparative study

deletion mutant

dimerization

eukaryote

genetic analysis

genetic code

molecular weight

mutation

nonhuman

photosynthesis

priority journal

prokaryote

protein analysis

protein assembly

protein binding

protein function

protein localization

protein stability

protein structure

review

sequence analysis

sequence homology

structure analysis

Amino Acid Sequence

Chloroplasts

Crystallography

Cyanobacteria

Molecular Sequence Data

Peptides

Phosphoproteins

Photosystem II Protein Complex

Plant Proteins

algae

Embryophyta

Eukaryota

Prokaryota

Publikations- och innehållstyp

ref (ämneskategori)

art (ämneskategori)