Abstract
The endoplasmic reticulum (ER) forms a dynamic polygonal network composed of tubules, sheets, and three-way junctions. Although the complex ER morphology supports the diverse cellular functions, the molecular mechanisms responsible for the organization of these structures are obscure. Here we report the isolation and characterization of mutants of Arabidopsis thaliana that are defective in ER morphology (ermo1, ermo2, and ermo3). Among three mutants, ermo1 and ermo2, which showed partially similar phenotypes, were defective in GNOM-LIKE1 (GNL1) and SEC24a, respectively (1). Both GNL1/ERMO1 and SEC24a/ERMO2 were thought to be involved in the ER-Golgi transport. Our results suggests that the unknown cargo proteins that are specifically transported by GNL1/ERMO1 and SEC24a/ERMO2 may have crucial roles. On the other hand, we identified the responsible gene for ermo3 to be a member of GDSL-motif lipase family, which is predicted to be localized within the vacuoles. Our findings suggest a novel pathway that connects ER morphology to lipid metabolic processes.
(1) Nakano, R.T. et al., Plant Cell,10.1105/tpc.109.068270 (2009).
