title: Identification of a Taraxacum brevicorniculatum rubber elongation factor protein that is localized on rubber particles and promotes rubber biosynthesis.
abstract: Two protein families required for rubber biosynthesis in Taraxacum brevicorniculatum have recently been characterized, namely the cis-prenyltransferases (TbCPTs) and the small rubber particle proteins (TbSRPPs). The latter were shown to be the most abundant proteins on rubber particles, where rubber biosynthesis takes place. Here we identified a protein designated T. brevicorniculatum rubber elongation factor (TbREF) by using mass spectrometry to analyze rubber particle proteins. TbREF is homologous to the TbSRPPs but has a molecular mass that is atypical for the family. The promoter was shown to be active in laticifers, and the protein itself was localized on the rubber particle surface. In TbREF-silenced plants generated by RNA interference, the rubber content was significantly reduced, correlating with lower TbCPT protein levels and less TbCPT activity in the latex. However, the molecular mass of the rubber was not affected by TbREF silencing. The colloidal stability of rubber particles isolated from TbREF-silenced plants was also unchanged. This was not surprising because TbREF depletion did not affect the abundance of TbSRPPs, which are required for rubber particle stability. Our findings suggest that TbREF is an important component of the rubber biosynthesis machinery in T. brevicorniculatum, and may play a role in rubber particle biogenesis and influence rubber production.
authors: Fraunhofer Institute for Molecular Biology and Applied Ecology, Schlossplatz 8, Münster, 48143, Germany.
authors: Natalie
authors: N
authors: Laibach
authors: Westphalian Wilhelms University of Münster, Institute of Plant Biology and Biotechnology, Schlossplatz 8, Münster, 48143, Germany.
authors: Andrea
authors: A
authors: Hillebrand
authors: TRM Ltd, York, YO43 3WE, UK.
authors: Richard M
authors: RM
authors: Twyman
authors: Fraunhofer Institute for Molecular Biology and Applied Ecology, Schlossplatz 8, Münster, 48143, Germany.|Westphalian Wilhelms University of Münster, Institute of Plant Biology and Biotechnology, Schlossplatz 8, Münster, 48143, Germany.
authors: Dirk
authors: D
authors: Prüfer
authors: Fraunhofer Institute for Molecular Biology and Applied Ecology, Schlossplatz 8, Münster, 48143, Germany.
authors: Christian
authors: C
authors: Schulze Gronover
mesh_terms: D018506:Gene Expression Regulation, Plant; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D012408:Rubber / Q000378:metabolism*; D031205:Taraxacum / Q000235:genetics / Q000378:metabolism*
chemical_list: D010940:Plant Proteins; D012408:Rubber
keywords: Taraxacum brevicorniculatum; latex; natural rubber; rubber; rubber elongation factor