Connecting plant peroxisomes

Over the past decade, significant progress in plant peroxisome research has been achieved since the discovery of peroxisomes in the 1960s. Genomic and proteomic approaches revealed unexpected metabolic functions for plant peroxisomes;besides photorespiration and lipid metabolism, plant peroxisomes play key roles in plant hormone biosynthesis, polyamine metabolism, and plant-pathogen interactions.

To connect peroxisomes with other plant cell compartments, specific transport proteins are required to enable the exchange of metabolic precursors, intermediates, and end products with other compartments of the cell. Given the large number of substrates that are transported across the peroxisomal membrane, a wide spectrum of metabolite transporters is postulated. However, despite the importance of peroxisomes for the functioning of plant cells, our knowledge of transporters in the peroxisomal membrane is still quite limited.

Recently, we identified peroxisomal membrane proteins required for the transport of ATP. These transporters have been named PNC1 and PNC2 (peroxisomal adenine nucleotide carrier 1 and 2). Many biochemical pathways in peroxisomes, such as fatty acid degradation, depend on supply with energy. Repression of PNC1 and PNC2 in Arabidopsis mutants severely affected seedling development due to a blockage in storage oil mobilization. This shows that plant peroxisomes are unable to synthesize ATP and are fully dependent on the import of ATP from the cytosol.

Ethanol-inducible repression of both peroxisomal ATP transporter proteins PNC1 and PNC2 in Arabidopsis led to arrested seedling growth in the absence of exogenous sucrose.

Future Projects and Goals

The majority of peroxisomal transport proteins have not yet been identified at the molecular level, in plants as well as in other eukaryotic organisms.

To discover further transport proteins of plant peroxisomes, our group pursues several complementary strategies, such as proteome analysis of the peroxisomal membrane, as well as genetic and biochemical approaches in yeast and plants. Currently, we have identified two novel peroxisomal carrier proteins in Arabidopsis that mediate different transport processes.

The main focus of our group is to investigate:

  • The transport function of these prospective transporter proteins by biochemical uptake assays or electrophysiological measurements.
  • The phenotypic analysis of knockout plants will further help us to understand and pinpoint the impact of these carrier proteins for peroxisomal metabolism in plants.

 

Selected Articles

Linka N, Weber APM (2010) Intracellular metabolite transporters in plants. Mol Plant 3: 21-53. undefinedsee abstract...

Reumann S, Quan S, Aung K, Yang P, Manandhar-Shrestha K, et al. (2009) In-depth proteome analysis of Arabidopsis leaf peroxisomes combined with in vivo subcellular targeting verification indicates novel metabolic and regulatory functions of peroxisomes. Plant Physiol 150: 125-143. undefinedread article...

Linka N, Theodoulou FL, Haslam RP, Linka M, Napier JA, et al. (2008) Peroxisomal ATP import is essential for seedling development in Arabidopsis thaliana. Plant Cell 20: 3241-3257. undefinedread article...

  

 

 

Photos: Hanne Horn & Nicole Linka

Dr. Nicole Linka

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Curriculum Vitae

Ph.D. work with Ekkehard Neuhaus, Technical University Kaiserslautern (1998-2001)

Postdoctoral work with Ekkehard Neuhaus, Technical University Kaiserslautern (2001-2003)

Postdoctoral work (Alexander-von-Humboldt fellow) with Prof. Weber, Michigan State University, USA (2003-2007)

Research Associate, Institute for Plant Biochemistry, Heinrich Heine University Düsseldorf (since 2007)

Verantwortlich für den Inhalt: E-Mail sendenA.P.M Weber