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Effect of Medicago sativa Mhb1gene expression on defense response of Arabidopsis thaliana plants

100%

Maassen A., Hennig J.

2011

vol. 58

issue 3

427-432

Besides the previously described nitric oxide-detoxification activity we identified new features of class-1 non-symbiotic hemoglobin from Medicago sativa (Mhb1). Under in vitro conditions, using peroxidase in-gel activity assay, the Mhb1 protein was shown to possess also peroxidase-like activity. Due to this activity, in the presence of nitrite and hydrogen peroxide, the protein can mediate autonitration and nitration of other proteins at tyrosine residues, as revealed by tandem mass spectrometry and immune assay approaches. Mhb1 through its multifunctional activities can affect different components of signal transduction cascades operating during plant response to infections. This influence is manifested by Mhb1-mediated selective up-regulation of expression of certain pathogen inducible genes in Pseudomonas syringae infected Arabidopsis thaliana plants which overproduce Mhb1, as revealed by reverse transcription-quantitative real-time PCR analysis. Changes in expression level of these genes can influence such processes as synthesis of secondary metabolites, protein degradation and biosynthesis of ethylene. They can also result in alteration of pathogen-induced defense response of Mhb1 transgenic plants.

Conserved Cys residue influences catalytic properties of potato endo-(1→3)-β-glucanase GLUB20-2

81%

Witek A. I., Witek K., Hennig J.

2008

vol. 55

issue 4

791-797

The synthesis and degradation of (1→3)-β-glycosidic bonds between glucose moieties are essential metabolic processes in plant cell architecture and function. We have found that a unique, conserved cysteine residue, positioned outside the catalytic centre of potato endo-(1→3)-β-glucanase - product of the gluB20-2 gene, participates in determining the substrate specificity of the enzyme. The same residue is largely responsible for endo-(1→3)-β-glucanase inhibition by mercury ions. Our results confirm that the spatial adjustment between an enzyme and its substrate is one of the essential factors contributing to the specificity and accuracy of enzymatic reactions.

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2 Acta Biochimica Polonica

1 2011

1 2008

2 Hennig J.

1 Maassen A.

1 Witek A. I.

1 Witek K.

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Effect of Medicago sativa Mhb1gene expression on defense response of Arabidopsis thaliana plants

Conserved Cys residue influences catalytic properties of potato endo-(1→3)-β-glucanase GLUB20-2