Lhcb5 | CP26 chlorophyll a/b-binding protein of plant PSII

Dicots, Gymnosperms

5 µg protein of (1) chloroplasts, (2) thylakoids, and (3) Photosystem I of Arabidopsis thaliana together with (4) BBY (Photosystem II) -particles from Pisum sativum were separated on 4-12% NuPage (Invitrogen) LDS-PAGE and blotted 1h to nitrocellulose. Filters were blocked 1h with 2% low-fat milk powder in TBS-T (0.1% TWEEN 20) and probed with anti-Lhcb5 (AS01 009, 1:1000, 1h) and secondary anti-rabbit (1:20 000, 1 h) antibody (HRP conjugated) in TBS-T containing 2% low fat milk powder. Antibody incubations were followed by washings in TBS-T (15, +5, +5, +5 min). All steps were performed at RT with agitation. Signal was detected with chemiluminescence detection reagent, using a Fuji LAS-3000 CCD (90s, standard sensitivity).

1 µg of chlorophyll from chloroplasts of: Pisum sativum (1), Echinochloa crus-galli, M chloroplasts (2), Echinochloa crus-galli, BS (bundle sheath) chloroplasts (3), Zea mays M chloroplasts (4), Zea mays BS (bundle sheath) chloroplasts (5), extracted with 0.4 M sorbitol, 50 mM Hepes NaOH, pH 7.8, 10 mM NaCl, 5 mM MgCl2 and 2 mM EDTA. Samples were denatured with Laemmli buffer at 75ºC for 5 min and were separated on 12% SDS-PAGE and blotted 30 min to PVDF using wet transfer. Blot was blocked with 5% milk for 2h at room temperature (RT) with agitation. Blot was incubated in the primary antibody at a dilution of 1: 1000 overnight at 4ºC with agitation in 1% milk in TBS-T. The antibody solution was decanted and the blot was washed 4 times for 5 min in TBS-T at RT with agitation. Blot was incubated in secondary antibody (anti-rabbit IgG horse radish peroxidase conjugated, from Agrisera, AS09 602, Lot 2001) diluted to 1:20 000 in  1 % milk in TBS-T for 1h at RT with agitation. The blot was washed 5 times for 5 min in TBS-T and 2 times for 5 min in TBS, and developed for 1 min with 1.25 mM luminol, 0.198 mM coumaric acid and 0.009% H2O2 in 0.1 M Tris- HCl, pH 8.5. Exposure time in ChemiDoc System was 73 seconds.

Courtesy of Dr. Wioleta Wasilewska-Dębowska, Warsaw University, Poland

Lhcb5 is one of the 3 minor highly conserved chlorophyll a/b-binding proteins associated with Photosystem II in plants and algae. As a part of the inner light-harvesting antenna it has been sugested to regulate (together with Lhcb4 and Lhcb6) the energy flow from the outer LHCII antenna to the PSII reaction center.