Fast Diffusion of the Unassembled PetC1-GFP Protein in the Cyanobacterial Thylakoid Membrane

0542412 - MBÚ 2022 RIV CH eng J - Journal Article
Kaňa, Radek - Steinbach, G. - Sobotka, Roman - Vamosi, G. - Komenda, Josef
Fast Diffusion of the Unassembled PetC1-GFP Protein in the Cyanobacterial Thylakoid Membrane.
Life. Roč. 11, č. 1 (2021), č. článku 15. E-ISSN 2075-1729
R&D Projects: GA ČR(CZ) GA19-11494S; GA MŠMT(CZ) ED2.1.00/19.0392
EU Projects: European Commission(CZ) 854126 - PhotoRedesign
Institutional support: RVO:61388971
Keywords : proteins mobility * photosynthesis * fcs * thylakoids * cyanobacteria
OECD category: Microbiology
Impact factor: 3.253, year: 2021
Method of publishing: Open access
https://www.mdpi.com/2075-1729/11/1/15

Biological membranes were originally described as a fluid mosaic with uniform distribution of proteins and lipids. Later, heterogeneous membrane areas were found in many membrane systems including cyanobacterial thylakoids. In fact, cyanobacterial pigment-protein complexes (photosystems, phycobilisomes) form a heterogeneous mosaic of thylakoid membrane microdomains (MDs) restricting protein mobility. The trafficking of membrane proteins is one of the key factors for long-term survival under stress conditions, for instance during exposure to photoinhibitory light conditions. However, the mobility of unbound 'free' proteins in thylakoid membrane is poorly characterized. In this work, we assessed the maximal diffusional ability of a small, unbound thylakoid membrane protein by semi-single molecule FCS (fluorescence correlation spectroscopy) method in the cyanobacterium Synechocystis sp. PCC6803. We utilized a GFP-tagged variant of the cytochrome b(6)f subunit PetC1 (PetC1-GFP), which was not assembled in the b(6)f complex due to the presence of the tag. Subsequent FCS measurements have identified a very fast diffusion of the PetC1-GFP protein in the thylakoid membrane (D = 0.14 2.95 mu m(2)s(-1)). This means that the mobility of PetC1-GFP was comparable with that of free lipids and was 50-500 times higher in comparison to the mobility of proteins (e.g., IsiA, LHCII-light-harvesting complexes of PSII) naturally associated with larger thylakoid membrane complexes like photosystems. Our results thus demonstrate the ability of free thylakoid-membrane proteins to move very fast, revealing the crucial role of protein-protein interactions in the mobility restrictions for large thylakoid protein complexes.
Permanent Link: http://hdl.handle.net/11104/0319824