Small rubber particle protein 1 of Hevea brasiliensis exhibits biophysical characteristics similar to apolipoproteins

Plants produce natural rubber in specialized organelles, termed rubber particles (RP). The structure of the RP consists of a polyisoprene (rubber) core surrounded by a shell layer composed of a lipid monolayer and proteins. Among the prominent RP-associated proteins is small rubber particle protein (SRPP), the second most abundant protein on the Hevea brasiliensis rubber particle monolayer membrane. In this study, a combination of protein modeling, biophysical analysis, biochemistry, and transmission electron microscopy have been utilized to further characterize Hevea SRPP1 (HbSRPP1) membrane architectural rearrangement capabilities. Results obtained reveal that HbSRPP1 possesses characteristics reminiscent of apolipoproteins, including the ability to reorganize aqueous phospholipid dispersions into stable, disk-shaped nanoparticles, termed nanodisks. This research provides the groundwork for further studies into the mechanism of SRPP's interaction with the RP membrane surface which likely involves conformational changes in RP topology.