Light-harvesting protein LHCB5 is one of the three minor antenna proteins (LHCB4-6) that connect the core (C) of photosystem II (PSII) with strongly (S) and moderately (M) bound peripheral trimeric antennae (LHCIIs), forming a dimeric PSII supercomplex known as C2S2M2. Plants lacking LHCB4 and LHCB6 do not form C2S2M2, indicating that these minor antenna proteins are crucial for C2S2M2 assembly. However, studies on antisense asLhcb5 plants suggest this may not apply to LHCB5. Using mild clear-native PAGE (CN-PAGE) and electron microscopy (EM), we separated and structurally characterized the C2S2M2 supercomplex from the Arabidopsis lhcb5 mutant. When compared with wild type (WT), the C2S2M2 supercomplexes in the lhcb5 mutant have slightly different positions of S and M trimers and are generally smaller and present in the thylakoid membrane at higher density. Using CN-PAGE, we did not observe any PSII megacomplexes in the lhcb5 mutant, although they are routinely detected by this method in WT. However, we identified the megacomplexes directly in thylakoid membranes via EM, indicating that the megacomplexes are formed but are too labile to be separated. While in WT, both parallel- and non-parallel-associated PSII supercomplexes can be detected in the thylakoid membrane (Nosek et al., 2017, Plant Journal 89, pp. 104-111), only the parallel-associated PSII supercomplexes were found in the lhcb5 mutant. This finding suggests that the formation of non-parallel-associated PSII supercomplexes depends on the presence of LHCB5. The presence of large PSII supercomplexes and megacomplexes, even though less stable, could explain the WT-like photosynthetic characteristics of the lhcb5 mutant.

• MeSH
• Arabidopsis * metabolismus   genetika   MeSH
• fotosystém II (proteinový komplex) * metabolismus   genetika   MeSH
• mutace MeSH
• proteiny huseníčku * metabolismus   genetika   MeSH
• proteiny vázající chlorofyl MeSH
• světlosběrné proteinové komplexy * metabolismus   genetika   MeSH
• tylakoidy * metabolismus   ultrastruktura   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• fotosystém II (proteinový komplex) * MeSH
• LHCB5 protein, Arabidopsis MeSH Prohlížeč
• proteiny huseníčku * MeSH
• proteiny vázající chlorofyl MeSH
• světlosběrné proteinové komplexy * MeSH