Yang Xu (Benning lab)
Date & Location: December 1, 2020, at 12p; Virtual talk
Subject: Probing possible links between a predicted rhomboid-like protease 10 and galactolipids biosynthesis in Arabidopsis
Abstract: In Arabidopsis, the majority of fatty acids are synthesized in the chloroplast. The de novo synthesized fatty acids are either directly assembled into galactolipids at the chloroplast envelope membranes or exported to the ER for glycerolipid biosynthesis. After being assembled, a fraction of ER-derived glycerol lipids is then re-imported into the chloroplast and contributes to the synthesis of thylakoid lipids. Due to the distinct substrate specificity of acyltransferases in the chloroplast and ER lipid biosynthesis, thylakoid lipids synthesized from chloroplast and ER lipid precursors have a 16-carbon and 18-carbon acyl chain at the sn-2 position, respectively, thus leading to a specific 16:3/18:3 ratio of acyl chains in galactolipids of Arabidopsis. Previously, the Benning lab identified a predicted rhomboid-like protease 10 (RBL10), that affects the 16:3/18:3 ratio of acyl chains in galactolipids in Arabidopsis and may form a large protein complex (>660kDa) in the chloroplast.
Further probing for possible RBL10 interactors found acyl-carrier protein 4 (ACP4) as a protein interactor of RBL10, which is a protein carrying the nascent acyl chains and has crucial roles in fatty acid biosynthesis and subsequent lipid assembly, modification and export. The Arabidopsis acp4 mutant has a similar lipid phenotype (decreased 16:3 and increased 18:3 acyl chain amount in MGDG) to that of rbl10, which links RBL10 to lipid metabolism in the plastid. To further probe the relation of RBL10 and ACP4 to galactolipids biosynthesis, I am currently testing the in vitro properties of RBL10, characterizing Arabidopsis acp4 mutant lines and explore the genetic interaction between RBL10 and ACP4. Additionally, other research plans including a proximity biotinylation labeling strategy to probe potential substrates of RBL10 and the local proteome in the chloroplast will also be discussed.
Speaker Lab: Dr. Christoph Benning