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The syringaldazine-oxidizing peroxidase PXP 3-4 from poplar xylem: cDNA isolation, characterization and expression
J H Christensen1, S Overney, A Rohde
1Vakgroep Moleculaire Genetica, Departement Plantengenetica, Vlaams Interuniversitair Instituut voor Biotechnologie (VIB), Universiteit Gent, Belgium.
Plant Molecular Biology
|December 1, 2001
Summary
Two poplar peroxidases, PXP 3-4 and PXP 5, are key to lignin biosynthesis in plant cell walls. These enzymes catalyze syringaldazine oxidation, supporting their role in secondary cell wall formation.
Area of Science:
- Plant Biology
- Biochemistry
- Molecular Biology
Background:
- Lignin, a key plant cell wall polymer, is synthesized by oxidoreductases.
- Peroxidase-driven oxidation of syringaldazine (SYR) occurs in plant cells undergoing secondary wall formation, including lignification.
Purpose of the Study:
- To identify and characterize peroxidases involved in lignin biosynthesis in poplar (Populus trichocarpa).
- To confirm the role of isolated anionic isoenzymes PXP 3-4 and PXP 5 in SYR oxidation within developing xylem.
Main Methods:
- Isolation of anionic isoenzymes PXP 3-4 and PXP 5 from poplar xylem.
- Isolation of cDNA for PXP 3-4 and heterologous expression in a baculovirus system.
- Characterization of recombinant PXP 3-4 and comparison with native enzyme.
Main Results:
- PXP 3-4 and PXP 5 were identified as SYR-oxidizing peroxidases in poplar xylem.
- Recombinant PXP 3-4 exhibited similar enzymatic properties to the native enzyme.
- PXP 3-4 expression was confirmed in stem and root xylem, localizing it to differentiating xylem.
Conclusions:
- PXP 3-4 and PXP 5 are demonstrably involved in SYR oxidation in poplar xylem.
- These peroxidases likely play a crucial role in secondary cell wall formation and lignification.