Arabidopsis Nonsymbiotic Hemoglobin AHb1 Modulates Nitric Oxide Bioactivity

Abstract

Nitric oxide (NO) is a widespread signaling molecule, and numerous targets of its action exist in plants. Whereas the activity of NO in erythrocytes, microorganisms, and invertebrates has been shown to be regulated by several hemoglobins, the function of plant hemoglobins in NO detoxification has not yet been elucidated. Here, we show that Arabidopsis thaliana nonsymbiotic hemoglobin AHb1 scavenges NO through production of S-nitrosohemoglobin and reduces NO emission under hypoxic stress, indicating its role in NO detoxification. However, AHb1 does not affect NO-mediated hypersensitive cell death in response to avirulent Pseudomonas syringae, suggesting that it is not involved in the removal of NO bursts originated from acute responses when NO mediates crucial defense signaling functions.

Peroxisomes Are Required for in Vivo Nitric Oxide Accumulation in the Cytosol following Salinity Stress of Arabidopsis Plants

“…This plant has been used in many plant studies to determine the involvement of NO in seed germination (Beligni and Lamattina, 2000;Batak et al, 2002;Bethke et al, 2006), biotic stress (Delledonne et al, 1998(Delledonne et al, , 2001), abiotic stress (Mackerness et al, 2001;Huang et al, 2004), programmed cell death (Clarke et al, 2000;Zhang et al, 2003), stomatal closure (Garcia-Mata et al, 2003;Desikan et al, 2004), iron metabolism (Murgia et al, 2004;Perazzolli et al, 2004), flowering (He et al, 2004;Simpson, 2005), and the protein S-nitrosylation (Feechan et al, 2005;Lindermayr et al, 2005), among others. Using the DAF-FM DA as a fluorescence probe, our results provide a detailed picture of the overall distribution of NO during the early development of 3-to 11-d-old Arabidopsis seedlings.…”

Cross Talk between Reactive Nitrogen and Oxygen Species during the Hypersensitive Disease Resistance Response

“…Different enzymatic routes also keep NO levels under control and contribute to its detoxification. Nonsymbiotic hemoglobins metabolize NO and S-nitrosoglutathione (GSNO; Perazzolli et al, 2004), GSNO reductase controls intracellular levels of S-nitrosothiols and GSNO (Feechan et al, 2005) and peroxiredoxins are likely involved in reduction of peroxynitrite (Rhee et al, 2005).…”

Insights into Hemoglobin Assembly through in Vivo Mutagenesis of α-Hemoglobin Stabilizing Protein

“…Autooxidation is followed immediately by internal coordination of His 58 (E7) to the hemin iron, resulting in a hexacoordinate bishistidyl or hemichrome structure (18,21,22,28). Bishistidyl hemoglobins occur as ␣-globin degradation products in ␤-thalassemia (4,6,29,30), during normal degradation of hemoglobin, and in some naturally occurring globins in mammalian tissues, plants, certain bacteria, and cold water fish (31)(32)(33)(34)(35)(36)(37)(38)(39)(40). Binding of His 58 to hemin iron appears to inhibit the ability of met-␣ to catalyze ROS production (39,41).…”