TY  - JOUR
AU  - Ferrante, P.
AU  - Ballottari, M.
AU  - Bonente, G.
AU  - Giuliano, G.
AU  - Bassi, R.
TI  - LHCBM1 and LHCBM2/7 polypeptides, components of the major LHCII complex, have distinct functional roles in the photosynthetic antenna system of Chlamydomonas reinhardtii
JO  - The journal of biological chemistry
VL  - 287
SN  - 0021-9258
CY  - Bethesda, Md.
PB  - Soc.
M1  - PreJuSER-22169
SP  - 16276 - 16288
PY  - 2012
N1  - This work was supported by the Italian Ministry of Agriculture, Hydrobio project, and by Euopean Union Project 245070 FP7-KBBE-2009-3 SUNBIOPATH.
AB  - The photosystem II antenna of Chlamydomonas reinhardtii is composed of monomeric and trimeric complexes, the latter encoded by LHCBM genes. We employed artificial microRNA technology to specifically silence the LHCBM2 and LHCBM7 genes, encoding identical mature polypeptides, and the LHCBM1 gene. As a control, we studied the npq5 mutant, deficient in the LHCBM1 protein. The organization of LHCII complexes, functional antenna size, capacity for photoprotection, thermal energy dissipation and state transitions, and resistance to reactive oxygen species was studied in the various genotypes. Silencing of the LHCBM2/7 genes resulted in a decrease of an LHCII protein with an apparent molecular mass of 22 kDa, whereas silencing/lack of LHCBM1 caused the decrease/disappearance of a 23-kDa protein. A decrease in the abundance of trimeric LHCII complexes and in functional antenna size was observed in both LHCBM2/7 and LHCBM1 knockouts. In agreement with previous data, depletion of LHCBM1 decreased the capacity for excess energy dissipation but not the ability to perform state transitions. The opposite was true for LHCBM2/7, implying that this polypeptide has a different functional role from LHCBM1. The abundance of LHCBM1 and LHCBM2/7 is in both cases correlated with resistance to superoxide anion, whereas only LHCBM1 is also involved in singlet oxygen scavenging. These results suggest that different LHCBM components have well defined, non-redundant functions despite their high homology, implying that engineering of LHCBM proteins can be an effective strategy for manipulating the light harvesting system of Chlamydomonas reinhardtii.
KW  - Chlamydomonas reinhardtii: enzymology
KW  - Chlamydomonas reinhardtii: genetics
KW  - Gene Silencing
KW  - MicroRNAs: genetics
KW  - MicroRNAs: metabolism
KW  - Photosystem II Protein Complex: genetics
KW  - Photosystem II Protein Complex: metabolism
KW  - Plant Proteins: genetics
KW  - Plant Proteins: metabolism
KW  - MicroRNAs (NLM Chemicals)
KW  - Photosystem II Protein Complex (NLM Chemicals)
KW  - Plant Proteins (NLM Chemicals)
KW  - J (WoSType)
LB  - PUB:(DE-HGF)16
C6  - pmid:22431727
C2  - pmc:PMC3351333
UR  - <Go to ISI:>//WOS:000304030900020
DO  - DOI:10.1074/jbc.M111.316729
UR  - https://juser.fz-juelich.de/record/22169
ER  -