High-light-inducible proteins HliA and HliB: pigment binding and protein-protein interactions

0561363 - MBÚ 2023 RIV NL eng J - Journal Article
Konert, Minna Maria - Wysocka, Anna - Koník, P. - Sobotka, Roman
High-light-inducible proteins HliA and HliB: pigment binding and protein-protein interactions.
Photosynthesis Research. Roč. 152, č. 3 (2022), s. 317-332. ISSN 0166-8595. E-ISSN 1573-5079
R&D Projects: GA ČR(CZ) GX19-29225X
EU Projects: European Commission(CZ) 854126 - PhotoRedesign
Institutional support: RVO:61388971
Keywords : Synechocystis * High-light-inducible proteins * Photosystem II * cp47 * Chlorophyll
OECD category: Plant sciences, botany
Impact factor: 3.7, year: 2022
Method of publishing: Limited access
https://link.springer.com/article/10.1007/s11120-022-00904-z

High-light-inducible proteins (Hlips) are single-helix transmembrane proteins that are essential for the survival of cyanobacteria under stress conditions. The model cyanobacterium Synechocystis sp. PCC 6803 contains four Hlip isoforms (HliA-D) that associate with Photosystem II (PSII) during its assembly. HliC and HliD are known to form pigmented (hetero)dimers that associate with the newly synthesized PSII reaction center protein D1 in a configuration that allows thermal dissipation of excitation energy. Thus, it is expected that they photoprotect the early steps of PSII biogenesis. HliA and HliB, on the other hand, bind the PSII inner antenna protein CP47, but the mode of interaction and pigment binding have not been resolved. Here, we isolated His-tagged HliA and HliB from Synechocystis and show that these two very similar Hlips do not interact with each other as anticipated, rather they form HliAC and HliBC heterodimers. Both dimers bind Chl and beta-carotene in a quenching conformation and associate with the CP47 assembly module as well as later PSII assembly intermediates containing CP47. In the absence of HliC, the cellular levels of HliA and HliB were reduced, and both bound atypically to HliD. We postulate a model in which HliAC-, HliBC-, and HliDC-dimers are the functional Hlip units in Synechocystis. The smallest Hlip, HliC, acts as a 'generalist' that prevents unspecific dimerization of PSII assembly intermediates, while the N-termini of 'specialists' (HliA, B or D) dictate interactions with proteins other than Hlips.
Permanent Link: https://hdl.handle.net/11104/0334498