Distribution and Functions of Monodehydroascorbate Reductases in Plants: Comprehensive Reverse Genetic Analysis of Arabidopsis thaliana Enzymes

Monodehydroascorbate reductase (MDAR) is an enzyme involved in ascorbate recycling. Arabidopsis thaliana has five MDAR genes that encode two cytosolic, one cytosolic/peroxisomal, one peroxisomal membrane-attached, and one chloroplastic/mitochondrial isoform. In contrast, tomato plants possess only three enzymes, lacking the cytosol-specific enzymes. Thus, the number and distribution of MDAR isoforms differ according to plant species. Moreover, the physiological significance of MDARs remains poorly understood. In this study, we classify plant MDARs into three classes: class I, chloroplastic/mitochondrial enzymes; class II, peroxisomal membrane-attached enzymes; and class III, cytosolic/peroxisomal enzymes. The cytosol-specific isoforms form a subclass of class III and are conserved only in Brassicaceae plants. With some exceptions, all land plants and a charophyte algae, Klebsormidium flaccidum, contain all three classes. Using reverse genetic analysis of Arabidopsis thaliana mutants lacking one or more isoforms, we provide new insight into the roles of MDARs; for example, (1) the lack of two isoforms in a specific combination results in lethality, and (2) the role of MDARs in ascorbate redox regulation in leaves can be largely compensated by other systems. Based on these findings, we discuss the distribution and function of MDAR isoforms in land plants and their cooperation with other recycling systems.

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Faculty Opinions recommendation of Stable transformation and reverse genetic analysis of Penium margaritaceum: a platform for studies of charophyte green algae, the immediate ancestors of land plants.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.718258389.793496508 ◽

2014 ◽

Author(s):

Staffan Persson ◽

Clara Sanchez-Rodriguez

Keyword(s):

Genetic Analysis ◽

Green Algae ◽

Stable Transformation ◽

Land Plants ◽

Reverse Genetic

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Reverse Genetic Analysis of Antiviral Resistance Signaling and the Resistance Mechanism in Arabidopsis thaliana

Methods in Molecular Biology - Antiviral Resistance in Plants ◽

10.1007/978-1-4939-9635-3_3 ◽

2019 ◽

pp. 27-84

Author(s):

Yukiyo Sato ◽

Hideki Takahashi

Keyword(s):

Arabidopsis Thaliana ◽

Genetic Analysis ◽

Resistance Mechanism ◽

Antiviral Resistance ◽

Reverse Genetic

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Conservation of targeting but divergence in function and quality control of peroxisomal ABC transporters: an analysis using cross-kingdom expression

Biochemical Journal ◽

10.1042/bj20110249 ◽

2011 ◽

Vol 436 (3) ◽

pp. 547-557 ◽

Cited By ~ 27

Author(s):

Xuebin Zhang ◽

Carine De Marcos Lousa ◽

Nellie Schutte-Lensink ◽

Rob Ofman ◽

Ronald J. Wanders ◽

...

Keyword(s):

Quality Control ◽

Arabidopsis Thaliana ◽

Abc Transporters ◽

Plant Cells ◽

Related Protein ◽

Peroxisomal Membrane ◽

And Function ◽

Native Host

ABC (ATP-binding cassette) subfamily D transporters are found in all eukaryotic kingdoms and are known to play essential roles in mammals and plants; however, their number, organization and physiological contexts differ. Via cross-kingdom expression experiments, we have explored the conservation of targeting, protein stability and function between mammalian and plant ABCD transporters. When expressed in tobacco epidermal cells, the mammalian ABCD proteins ALDP (adrenoleukodystrophy protein), ALDR (adrenoleukodystrophy-related protein) and PMP70 (70 kDa peroxisomal membrane protein) targeted faithfully to peroxisomes and P70R (PMP70-related protein) targeted to the ER (endoplasmic reticulum), as in the native host. The Arabidopsis thaliana peroxin AtPex19_1 interacted with human peroxisomal ABC transporters both in vivo and in vitro, providing an explanation for the fidelity of targeting. The fate of X-linked adrenoleukodystrophy disease-related mutants differed between fibroblasts and plant cells. In fibroblasts, levels of ALDP in some ‘protein-absent’ mutants were increased by low-temperature culture, in some cases restoring function. In contrast, all mutant ALDP proteins examined were stable and correctly targeted in plant cells, regardless of their fate in fibroblasts. ALDR complemented the seed germination defect of the Arabidopsis cts-1 mutant which lacks the peroxisomal ABCD transporter CTS (Comatose), but neither ALDR nor ALDP was able to rescue the defect in fatty acid β-oxidation in establishing seedlings. Taken together, our results indicate that the mechanism for trafficking of peroxisomal membrane proteins is shared between plants and mammals, but suggest differences in the sensing and turnover of mutant ABC transporter proteins and differences in substrate specificity and/or function.

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