Maassen Anna, Hennig Jacek
Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warszawa, Poland.
Acta Biochim Pol. 2011;58(3):427-32. Epub 2011 Jul 4.
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.
除了我们之前描述的一氧化氮解毒活性外，我们还鉴定了紫花苜蓿1类非共生血红蛋白（Mhb1）的新特性。在体外条件下，通过过氧化物酶凝胶活性测定，Mhb1蛋白还表现出类似过氧化物酶的活性。由于这种活性，在亚硝酸盐和过氧化氢存在的情况下，串联质谱和免疫分析方法表明，该蛋白可以介导其他蛋白质在酪氨酸残基处的自动硝化和硝化作用。Mhb1通过其多功能活性可以影响植物对感染反应过程中信号转导级联的不同组分。逆转录-定量实时PCR分析表明，这种影响表现为Mhb1介导的在过量表达Mhb1的丁香假单胞菌感染的拟南芥植物中某些病原体诱导基因表达的选择性上调。这些基因表达水平的变化可以影响次生代谢物合成、蛋白质降解和乙烯生物合成等过程。它们还可能导致Mhb1转基因植物病原体诱导的防御反应发生改变。
