Salt stress is the main constraint that limits agronomic output in several regions of the world. For the development of salt-tolerant crops, it is necessary to understand the salt-responsive proteins in halophytes. Myriostachya wightiana is a salt marsh that belongs to Poaceae. In this work, comparative proteomic studies were used to identify the proteins responsible for salt tolerance in the M. wightiana using two-dimensional electrophoresis and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). Two protein spots 48 and 14 were over-expressed from salt-stressed M. wightiana and they were identified as chloroplast adenosine triphosphate (ATP) synthase β and glutamine-dependent nicotinamide adenine dinucleotide (NAD+) synthetase. The physicochemical characterization revealed that the ATP synthase β and glutamine-dependent NAD+ synthetase have 31714.6 and 66481.8 Da respective molecular weights. The secondary structure of ATP synthase β and Glutamine-dependent NAD+ synthetase has a greater percentage of random coils and alpha helix respectively. The modeled three-dimensional structures of ATP synthase β, Glutamine-dependent NAD+ synthetase have close similarities with 1fx0B and 3sytA. The functions of ATP synthase β and glutamine-dependent NAD+ synthetase were associated with the ATPase activity and non-covalent selective interaction with ATP correspondingly. This study provides information regarding salt-induced proteins to know the salt adaptation mechanisms for developing salt-resistant varieties.
Key words: Proteomics, 2D gel electrophoresis, Peptide mass fingerprint, ATP synthase β, Glutamine-dependent NAD+ synthetase, Ramachandran plot.
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