Light-dependent reversible phosphorylation of the minor photosystem II antenna Lhcb6 (CP24) occurs in lycophytes.
Evolution of vascular plants required compromise between photosynthesis and photodamage. We analyzed representative species from two divergent lineages of vascular plants, lycophytes and euphyllophytes, with respect to the response of their photosynthesis and light-harvesting properties to increasing light intensity. In the two analyzed lycophytes, Selaginella martensii and Lycopodium squarrosum, the medium phase of non-photochemical quenching relaxation increased under high light compared to euphyllophytes. This was thought to be associated with the occurrence of a further thylakoid phosphoprotein in both lycophytes, in addition to D2, CP43 and Lhcb1-2. This protein, which showed light intensity-dependent reversible phosphorylation, was identified in S. martensii as Lhcb6, a minor LHCII antenna subunit of PSII. Lhcb6 is known to have evolved in the context of land colonization. In S. martensii, Lhcb6 was detected as a component of the free LHCII assemblies, but also associated with PSI. Most of the light-induced changes affected the amount and phosphorylation of the LHCII assemblies, which possibly mediate PSI-PSII connectivity. We propose that Lhcb6 is involved in light energy management in lycophytes, participating in energy balance between PSI and PSII through a unique reversible phosphorylation, not yet observed in other land plants.
Department of Life Sciences and Biotechnologies, University of Ferrara, Corso Ercole I d'Este 32, Ferrara, 44121, Italy.
Lorenzo
L
Ferroni
Martina
M
Angeleri
Laura
L
Pantaleoni
Cristina
C
Pagliano
Paolo
P
Longoni
Francesco
F
Marsano
Eva-Mari
EM
Aro
Marjaana
M
Suorsa
Costanza
C
Baldisserotto
Martina
M
Giovanardi
Rino
R
Cella
Simonetta
S
Pancaldi
D000595:Amino Acid Sequence; D001483:Base Sequence; D002734:Chlorophyll / Q000378:metabolism; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D008027:Light; D045342:Light-Harvesting Protein Complexes / Q000378:metabolism* / Q000528:radiation effects; D032502:Lycopodium / Q000378:metabolism* / Q000528:radiation effects; D008969:Molecular Sequence Data; D010766:Phosphorylation; D010788:Photosynthesis / Q000528:radiation effects*; D045331:Photosystem I Protein Complex / Q000378:metabolism / Q000528:radiation effects; D045332:Photosystem II Protein Complex / Q000378:metabolism / Q000528:radiation effects; D010940:Plant Proteins / Q000378:metabolism / Q000528:radiation effects; D018749:RNA, Plant / Q000235:genetics; D032503:Selaginellaceae / Q000378:metabolism* / Q000528:radiation effects; D017422:Sequence Analysis, DNA; D013045:Species Specificity; D020524:Thylakoids / Q000378:metabolism / Q000528:radiation effects
D018076:DNA, Complementary; D045342:Light-Harvesting Protein Complexes; D045331:Photosystem I Protein Complex; D045332:Photosystem II Protein Complex; D010940:Plant Proteins; D018749:RNA, Plant; D002734:Chlorophyll
Lhcb6; Selaginella martensii; fluorescence; lycophytes; phosphorylation; photosynthesis