Showing papers by "Bonnie Bartel published in 2018"

Peroxisome Function, Biogenesis, and Dynamics in Plants

Abstract: Recent advances highlight understanding of the diversity of peroxisome contributions to plant biology and the mechanisms through which these essential organelles are generated.

Biology in Bloom: A Primer on the Arabidopsis thaliana Model System

Abstract: Arabidopsis thaliana could have easily escaped human scrutiny. Instead, Arabidopsis has become the most widely studied plant in modern biology despite its absence from the dinner table. Pairing diminutive stature and genome with prodigious resources and tools, Arabidopsis offers a window into the molecular, cellular, and developmental mechanisms underlying life as a multicellular photoautotroph. Many basic discoveries made using this plant have spawned new research areas, even beyond the verdant fields of plant biology. With a suite of resources and tools unmatched among plants and rivaling other model systems, Arabidopsis research continues to offer novel insights and deepen our understanding of fundamental biological processes.

A pex1 missense mutation improves peroxisome function in a subset of Arabidopsis pex6 mutants without restoring PEX5 recycling.

Abstract: Peroxisomes are eukaryotic organelles critical for plant and human development because they house essential metabolic functions, such as fatty acid β-oxidation. The interacting ATPases PEX1 and PEX6 contribute to peroxisome function by recycling PEX5, a cytosolic receptor needed to import proteins targeted to the peroxisomal matrix. Arabidopsis pex6 mutants exhibit low PEX5 levels and defects in peroxisomal matrix protein import, oil body utilization, peroxisomal metabolism, and seedling growth. These defects are hypothesized to stem from impaired PEX5 retrotranslocation leading to PEX5 polyubiquitination and consequent degradation of PEX5 via the proteasome or of the entire organelle via autophagy. We recovered a pex1 missense mutation in a screen for second-site suppressors that restore growth to the pex6-1 mutant. Surprisingly, this pex1-1 mutation ameliorated the metabolic and physiological defects of pex6-1 without restoring PEX5 levels. Similarly, preventing autophagy by introducing an atg7-null allele partially rescued pex6-1 physiological defects without restoring PEX5 levels. atg7 synergistically improved matrix protein import in pex1-1 pex6-1, implying that pex1-1 improves peroxisome function in pex6-1 without impeding autophagy of peroxisomes (i.e., pexophagy). pex1-1 differentially improved peroxisome function in various pex6 alleles but worsened the physiological and molecular defects of a pex26 mutant, which is defective in the tether anchoring the PEX1-PEX6 hexamer to the peroxisome. Our results support the hypothesis that, beyond PEX5 recycling, PEX1 and PEX6 have additional functions in peroxisome homeostasis and perhaps in oil body utilization.