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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.

journal_name

Proc Natl Acad Sci U S A

journal_title

Proceedings of the National Academy of Sciences of the United States of America

authors

Gonzalez KL,Ratzel SE,Burks KH,Danan CH,Wages JM,Zolman BK,Bartel B

doi

10.1073/pnas.1721279115

subject

Has Abstract

pub_date

2018-04-03 00:00:00

pages

E3163-E3172

issue

eissn

0027-8424

issn

1091-6490

pii

1721279115

journal_volume

115

pub_type

杂志文章

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