?2-COP is involved in early secretory traffic in Arabidopsis and is required for plant growth.

ABSTRACT: COP (coat protein) I-coated vesicles mediate intra-Golgi transport and retrograde transport from the Golgi to the endoplasmic reticulum. These vesicles form through the action of the small GTPase ADP-ribosylation factor 1 (ARF1) and the COPI heptameric protein complex (coatomer), which consists of seven subunits (?-, ?-, ?'-, ?-, ?-, ?- and ?-COP). In contrast to mammals and yeast, several isoforms for coatomer subunits, with the exception of ? and ?, have been identified in Arabidopsis. To understand the role of COPI proteins in plant biology, we have identified and characterized a loss-of-function mutant of ?2-COP, an Arabidopsis ?-COP isoform. The ?2-cop mutant displayed defects in plant growth, including small rosettes, stems and roots and mislocalization of p24?5, a protein of the p24 family containing a C-terminal dilysine motif involved in COPI binding. The ?2-cop mutant also exhibited abnormal morphology of the Golgi apparatus. Global expression analysis of the ?2-cop mutant revealed altered expression of plant cell wall-associated genes. In addition, a strong upregulation of SEC31A, which encodes a subunit of the COPII coat, was observed in the ?2-cop mutant; this also occurs in a mutant of a gene upstream of COPI assembly, GNL1, which encodes an ARF-guanine nucleotide exchange factor (GEF). These findings suggest that loss of ?2-COP affects the expression of secretory pathway genes.

SUBMITTER: Gimeno-Ferrer F 

PROVIDER: S-EPMC5441910 | biostudies-literature | 2017 Jan

REPOSITORIES: biostudies-literature