PEX16 contributions to peroxisome import and metabolism revealed by viable Arabidopsis pex16 mutants

Abstract

Peroxisomes rely on peroxins (PEX proteins) for biogenesis, importing membrane and matrix proteins, and fission. PEX16, which is implicated in peroxisomal membrane protein targeting and forming nascent peroxisomes from the endoplasmic reticulum (ER), is unusual among peroxins because it is inserted co‐translationally into the ER and localizes to both ER and peroxisomal membranes. PEX16 mutations in humans, yeast, and plants confer some common peroxisomal defects; however, apparent functional differences have impeded the development of a unified model for PEX16 action. The only reported pex16 mutant in plants, the Arabidopsis shrunken seed1 mutant, is inviable, complicating analysis of PEX16 function after embryogenesis. Here, we characterized two viable Arabidopsis pex16 alleles that accumulate negligible PEX16 protein levels. Both mutants displayed impaired peroxisome function − slowed consumption of stored oil bodies, decreased import of matrix proteins, and increased peroxisome size. Moreover, one pex16 allele exhibited reduced growth that could be alleviated by an external fixed carbon source, decreased responsiveness to peroxisomally processed hormone precursors, and worsened or improved peroxisome function in combination with other pex mutants. Because the mutations impact different regions of the PEX16 gene, these viable pex16 alleles allow assessment of the importance of Arabidopsis PEX16 and its functional domains.

Delineation of renal protein profiles in aristolochic acid I-induced nephrotoxicity in mice by label-free quantitative proteomics

“…Ces2e and Ces1 are carboxylesterases that play an important role in exogenous ester drug metabolism and endogenous lipid metabolism ( Lian et al, 2018 ), and their expression levels showed an increasing trend in this study. In addition, the disruption in the expression levels of the proteins Nudt19, Lonp2, and PEX16, which are related to mitochondrial and peroxisomal productivity ( Wu et al, 2018 ; Burkhart et al, 2019 ; Görigk et al, 2022 ), also reflected the metabolic disorders caused by AAI.…”

Plant peroxisome proteostasis—establishing, renovating, and dismantling the peroxisomal proteome

“…In addition to PEX3 and PEX19, Arabidopsis PEX16 assists in targeting PMPs that first insert into the ER [49]. Viable pex16 alleles show enlarged peroxisomes [50], and peroxisomes are enlarged or misshapen when PEX3, PEX16, or PEX19 levels are reduced via RNAi [51]. Exploration of PEX3 and PEX19 functions is complicated by gene duplications resulting in two isoforms of both peroxins in Arabidopsis [20,52].…”

Plant peroxisomes: Small organelles with versatility and complexity

“…Arabidopsis pex16 null mutants are inviable because of the essential role of peroxisomes in embryogenesis. Burkhart et al (2019) have identified two viable pex16 alleles, which allowed them to dissect the function of PEX16 in peroxisome protein import and growth beyond embryogenesis in Arabidopsis, and assess the functional domains of PEX16.…”