Psb35 Protein Stabilizes the CP47 Assembly Module and Associated High-Light Inducible Proteins during the Biogenesis of Photosystem II in the CyanobacteriumSynechocystissp. PCC6803

Abstract

Photosystem II (PSII) is a large membrane protein complex performing primary charge separation in oxygenic photosynthesis. The biogenesis of PSII is a complicated process that involves a coordinated linking of assembly modules in a precise order. Each such module consists of one large chlorophyll-binding protein, number of small membrane polypeptides, pigments and other cofactors. We isolated the CP47 antenna module from the cyanobacterium Synechocystis sp. PCC 6803 and found that it contains a 11 kDa protein encoded by the ssl2148 gene. This protein was named Psb35 and its presence in the CP47 module was confirmed by the isolation of FLAG-tagged version of Psb35. Using this pulldown assay we showed that the Psb35 remains attached to CP47 after the integration of CP47 into PSII complexes. However, the isolated Psb35-PSIIs were enriched with auxiliary PSII assembly factors like Psb27, Psb28-1, Psb28-2 and RubA while they lacked the lumenal proteins stabilizing the PSII oxygen evolving complex. In addition, the Psb35 also co-purified with a large unique complex of CP47 and PSI trimer. Absence of Psb35 led to a lower accumulation and decreased stability of the CP47 antenna module and associated high-light-inducible proteins but did not change the growth rate of the cyanobacterium under variety of light regimes. Nevertheless, in comparison with WT the Psb35-less mutant showed an accelerated pigment bleaching during prolonged dark incubation. The results suggest an involvement of Psb35 in the life cycle of cyanobacterial chlorophyll-binding proteins, especially CP47.

Roles of Small Subunits of Laccase (ssPOXA3a/b) in Laccase Production by Pleurotus eryngii var. ferulae

“…Dimerization is a simple intermolecular interaction closing the distance between two proteins. It also promotes the enzyme-active site and substrate to combine in a more suitable position that substantially increases the catalytic reaction rate of the receptor protein. , Faraco et al have proposed that in the absence of ssPOXA3a/b, the large subunit of Lacc2 may lose its natural catalytic structure more quickly. Relative to POXA3a, POXA3b had superior catalytic capacity and thermostability.…”

Advances in the Understanding of the Lifecycle of Photosystem II

“…The CP47 pre-complex contains PsbH, PsbL, PsbT, and possibly PsbM, PsbX, and PsbY [ 55 , 56 ]. The assembly factor Psb35 also associates with the CP47 pre-complex and was shown to stabilize it and its association with HliA and HliB (ScpC and SpcD) [ 57 ]. Psb35 itself is a homolog of the cyanobacterial one helix domain/HLIP family of proteins, but it is unknown whether it binds chlorophyll.…”

Photosystem II antenna modules CP43 and CP47 do not form a stable ‘no reaction centre complex’ in the cyanobacterium Synechocystis sp. PCC 6803

“…Two minor module forms were found besides the major CP43m and CP47m bands with nearly identical mobilities. A faster migrating CP43m' of about 105 kDa is known to lack at least the small subunit PsbZ (Komenda et al 2012a) while a slower migrating CP47m' (~ 150 kDa) contains an additional PSII assembly factor Psb35 (see Pascual-Aznar et al 2021). The 2D gel analysis also proved the identity of larger fluorescing bands as PSII(2), PSII(1) and RC47 since they all contained CP47 and the first two also CP43.…”