标题：Isolation of Novel Acid Soil-tolerant Isolates of Rhizobium from "Pigeon Pea" and Proteomic Characterization by Utilizing MALDI-TOF/TOF and "Peptide Mass Fingerprinting" Approach to Identify Genes Associated with Acid-soil Tolerance
摘要：Biological processes account for approximately 60% of the biosphere's fixed nitrogen. As concerns mount to the growing input of reactive nitrogen into environment, as part of a 'nitrogen cascade', an increased need to understanding 'Biological Nitrogen Fixation (BNF)' has become of paramount importance. Rhizobium spp. survival in soil is influenced by a combination of many variable parameters, with soil-acidity being prominent ones. Using 16SrRNA Ribotyping analysis we have identified novel strains of Rhizobium (GenBank Accession Numbers KF309195, KF309203 and KF309204) from pigeon pea, which are tolerant to acidic soil pH regimes. 'Two-Dimensional GelElectrophoresis (2-DE)', followed by MALDI-TOF-TOF (Peptide-Mass Fingerprinting) was performed to characterize several important 'Unique' protein differences amongst acid tolerant / acid in-tolerant Rhizobium isolates. Analysis of 14 (Fourteen) 'Unique' protein spots identified the genes implicated in the acid-soil tolerance. These genes were found to encode a wide range of functions, which are implicated in modulation of the chemo-taxis system, required for virulence, enzymes that catalyze redox transformations, biosynthesis / intermediary metabolism / detoxification, export / import of a wide variety of substrate, receptors for osmotic solutes produced, movement of diverse solutes, catalysis of the transfer of a methyl group, transport large folded proteins / Na+ dependent unidirectional secondary transporters and cellular metabolism respectively. One of the important protein was identified as 'Chain A, Structure Of Periplasmic Binding Protein' (Accession Number: gi88192851, Molecular weight: 33,300Da and PI: 7.80). The periplasmic binding proteins serve as chemo-receptors, recognition constituents of transport systems, and initiators of signal transduction pathways. The existence of such unique proteins in the acid-tolerant isolates of Rhizobium is believed to explain the molecular basis of the factors responsible for imparting selective acid tolerance and better understanding of the molecular basis of leguminous plant nodules interaction, structure and function.
关键词：Biological Nitrogen Fixation; Rhizobium; Two-Dimensional Gel Electrophoresis; Mass Spectrophotometry
