Coexistence of Both Oleosin Isoforms on the Surface of Seed Oil Bodies and Their Individual Stabilization to the Organelles

Abstract

The oil bodies of plant seeds contain a triacylglycerol matrix surrounded by a monolayer of phospholipids embedded with alkaline proteins termed oleosins. Two distinct oleosin isoforms with molecular masses of 18 and 16 kDa are present in rice oil bodies. Chicken antibodies raised against oleosin 18 kDa and rabbit antibodies raised against oleosin 16 kDa did not cross-recognize these two homologous isoforms. This peculiar non-cross recognition was used to locate the two oleosin isoforms on the surface of oil bodies via immunofluorescence detection using anti-chicken IgG conjugated with FITC (fluorescein isothiocyanate) and anti-rabbit IgG conjugated with Texas-Red. The results revealed that both oleosin isoforms resided on each oil body in vivo and in vitro. Artificial oil bodies were reconstituted via sonication using triacylglycerol, phospholipid, and oleosins. The results indicated that the two rice oleosin isoforms could stabilize artificial oil bodies individually whereas oleosin 16 kDa provided better stability to the organelles than oleosin 18 kDa.

Gene Family of Oleosin Isoforms and Their Structural Stabilization in Sesame Seed Oil Bodies

“…The result is in accord with that obtained with reconstituted oil bodies and rice oleosin isoforms. 10) Nevertheless, none of the oil bodies reconstituted under our experimental conditions maintained their integrity as natural seed oil bodies puriˆed from mature sesame seeds did, presumably because of imperfect reconstitution.…”

Integral Proteins in Plant Oil Bodies

“…Two distinct classes, H-and L-(high and low molecular weight) oleosins, are present in seed oil bodies of diverse angiosperms, and one or more isoforms may occur in each oleosin class of the same species [123]. It has been shown that H-and L-oleosins coexist on the surface of each oil body in seed cells of sesame [124]. The main difference between these two oleosin isoforms is an insertion of 18 residues in the C-terminal domain of H-oleosin, accounting for a 2 kDa difference in mass between the two classes found in many species [125][126][127].…”

Molecular Cloning, Expression, and Functional Characterization of a Cystatin from Pineapple Stem

“…The non-fusion recombinant cystatin over-expressed in E. coli was resolved by glycine-SDS-PAGE 19) and eluted according to the gel extraction method. 20) Antibodies against the recombinant nonfusion cystatin were raised in chickens, and immunoglobulins were purified from egg yolk for immunoassays. 21) In these immunoassays, the proteins resolved by SDS-PAGE were transferred on to a nitrocellulose membrane (Pall, Ann Arbor, MI, USA) in a Trans-Blot system (Bio-Rad, Hercules, CA, USA) according to the manufacturer's instructions.…”