Differential Detergent Stability of the Major Light-Harvesting Complex II in Thylakoids Isolated from Monocotyledonous and Dicotyledonous Plants

Abstract

A survey of isolated thylakoids from 11 different higher plant species (Spinacia oleracea L., Pisum sativum L., Vicia faba L., Brassica napus L., Vigna sinensis L., Vinca minor L., Secale cereale L., Triticum aestivum L., Triticosecale Wittn., Hordeum vulgare L., Zea mays L.) indicated that the ratio of the oligomeric:monomeric form of the light-harvesting complex 11 was twofold higher for the dicots (3.16 ± 0.35) than the monocots (1.64 ± 0.25) examined under identical separation procedures. Under conditions specifically designed to stabilize the oligomeric form in vitro, we show that the oligomeric form of dicot light-harvesting complex 11 is twice as stable to solubilization in the presence of sodium dodecyl sulfate (SDS) than that observed for monocots. This decreased stability of monocot light-harvesting complex 11 is associated with a twofold increase in the trienoic fatty acid level of thylakoid phosphatidylglycerol but with no significant changes in the trienoic fatty acid levels in the major galactolipids. In addition, SDS polyacrylamide gel electrophoresis and western blot analyses with monoclonal antibodies indicated that monocots exhibited greater heterogeneity in the polypeptide complements associated with subtractions of light-harvesting complex 11 than the dicots examined. The data indicate that the oligomeric form of the lightharvesting complex 11 is not the result of a simple oligomerization of a common monomeric unit. We suggest that the difference in stability of the oligomeric form of light-harvesting complex 11 in isolated thylakoids of monocots and dicots is probably due to a differential accessibility to SDS. The differential SDS accessibility may be due to differences in thylakoid protein-protein and/or protein-lipid interactions.The major Chl a/b LHCII2 was one of the first pigment proteins to be characterized in higher plants (6,26,27 Approximately 50% of Chl and about 30% of the protein present in higher plant thylakoids is associated with LHCII (25, 26). The remainder of the Chl is associated with LHCI, core antennae, and reaction center complexes of PSII and PSI (10, 22). The oligomeric form (LHCIIb) of LHCII, with an apparent molecular mass of 72 kD and a Chl a/b of 1.0 to 1.3, is considered to be the primary form of this complex. Upon denaturation of the holocomplex with SDS, typically three to four polypeptides are observed in the molecular mass range of 25 to 30 kD. These polypeptides are the products of a family of light-regulated, nuclear-encoded cab genes (6, 11).Although the in situ form of LHCIIb is not known for certain, recent crystallographic (17, 18) and biochemical data indicate that LHCIIb most likely exists as a trimeric structure. Freeze-fracture data for thylakoid membranes indicate that the 80A particle identified as LHCIIb may be a higher oligomer than the proposed trimer (25). Kuhlbrandt and Wang (18) have shown by electron crystallography at 6A resolution that three membrane-spanning a helices (A, B, and C) exist within the LHCIIb trimer to which 15 Chl...

Isoforms of Photosystem II Antenna Proteins in Different Plant Species Revealed by Liquid Chromatography-Electrospray Ionization Mass Spectrometry

“…The band patterns seen after sucrose-gradient ultracentrifugal separation of PSII preparations from different species indicate that monocots show less oligomerization than dicots, suggesting that in dicots the trimers are more stable. This evidence agrees with a previous report that dicots appear to generate higher ratios of oligomeric-to-monomeric antenna system in vitro (47).…”

Differing involvement of sulfoquinovosyl diacylglycerol in photosystem II in two species of unicellular cyanobacteria

“…2.8 ± 0.2 (4) 2.6 ± 0.5 (5) deficiency on PSII activity had not been shown for Synechococcus sp. PCC7942, we produced an SQDGdeficient mutant of Synechococcus sp.…”

“…Significant differences in lipid composition and the fatty acid saturation state were observed, e.g. in extraction of photosystem II (PSII) from photosynthetic membranes with different detergents [5–7]. On the other hand, reconstitution of photosynthetic activity with the addition or removal of thylakoid lipids in vitro has also been performed with thylakoid membranes, subfractions of thylakoid membranes and purified protein complexes, with important observations being summarized in a review by Trémolières and Siegenthaler [8].…”

Low growth temperature inhibition of photosynthesis in cotyledons of jack pine seedlings (Pinus banksiana) is due to impaired chloroplast development

“…The membrane pellets were resuspended and solubilized in 0.3 M Tris (pH 8.8) containing 13% (v/v) glycerol and 1% (w/v) SDS (sodium dodecylsulfate), and then 2% (w/v) DOC (decoxycholate) in 0.3 M Tris (pH 8.8) was added immediately to give a DOC-SDS-Chl ratio of 20:10:1. The solubilized Chl-protein complexes were separated in the dark at 4°C in 7.5% (w/v) SDS polyacrylamide slab gels as described in detail elsewhere (Huner et al 1992).…”