Altered plant and nodule development and protein S-nitrosylation in Lotus japonicus mutants deficient in S-nitrosoglutathione reductases

Manuel A Matamoros, Maria C Cutrona, Stefanie Wienkoop, Juan C Begara-Morales, Niels Sandal, Irene Orera, Juan B Barroso, Jens Stougaard, Manuel Becana

Nitric oxide (NO) is a crucial signaling molecule that conveys its bioactivity mainly through protein S-nitrosylation. This is a reversible post-translational modification (PTM) that may affect protein function. S-nitrosoglutathione (GSNO) is a cellular NO reservoir and NO donor in protein S-nitrosylation. The enzyme S-nitrosoglutathione reductase (GSNOR) degrades GSNO, thereby regulating indirectly signaling cascades associated to this PTM. Here the two GSNORs of the legume Lotus japonicus, LjGSNOR1 and LjGSNOR2, have been functionally characterized. The LjGSNOR1 gene is very active in leaves and roots, whereas LjGSNOR2 is highly expressed in nodules. The enzyme activities are regulated in vitro by redox-based PTMs. Reducing conditions and hydrogen sulfide-mediated cysteine persulfidation induced both activities, whereas cysteine oxidation or glutathionylation inhibited them. Ljgsnor1 knockout mutants contained higher levels of S-nitrosothiols. Affinity chromatography and subsequent shotgun proteomics allowed us to identify 19 proteins that are differentially S-nitrosylated in the mutant and the wild-type. These include proteins involved in biotic stress, protein degradation, antioxidant protection and photosynthesis. We propose that, in the mutant plants, deregulated protein S-nitrosylation contributes to developmental alterations, such as growth inhibition, impaired nodulation and delayed flowering and fruiting. Our results highlight the importance of GSNOR function in legume biology.

External organisation(s)
Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Jaén, Aarhus University, Health Sciences Institute in Aragon
Plant and Cell Physiology
Publication date
Peer reviewed
Austrian Fields of Science 2012
106031 Plant physiology, 106037 Proteomics, 106002 Biochemistry
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