Intrinsically Disordered Protein At1g13930 And Its Responses To Abiotic Stresses

Intrinsically disordered proteins(IDPs) refer to proteins that lack well-defined three-dimensional structures, but display diverse biological functions, including signal transduction, transcriptional regulation, stress responses, under physiological conditions. Numbers of stress response proteins in plants are identified as IDPs, and their disordered regions are essential for diverse protein-protein, protein-membrane lipid, and protein-nucleic acid interactions. At1g13930 has been identified as plant-specific IDP; however, its function and mechanism have not been clearly elucidated.Bioinformatic analysis of primary sequence and disorder prediction, using PONDR ® VL-XT, MOBYLE, UCL method, showed that At1g13930 consists of 18 kinds of amino acids, and are enriched in disorder-promoting residues, including a remarkably high proportion of alanine, lysine, and proline residues. There are two segments highly disordered containing 61 aa and 32 aa residues. α-helices and random coils exist in At1g13930 which is structurally classified as pre-molten globule-like IDP. Phosphorylation and acetylation mainly occurs in disorder regions.Promoter of At1g13930 was analyzed for putative plant regulatory elements using the plantCARE, showing that At1g13930 contains several putative cis-acting elements that respond to environmental stresses, such as ABA, GA, drought, heat et al. To visualize the temporal and spatial expression of At1g13930 in response to different stresses, At1g13930P:GUS lines were studied alongside 35S:GUS(positive control) and negative controls. Staining was observed in leaves, roots, and in guard cells of stomata. No staining was detected in root tips, anthers and stigma. Promoter activity of At1g13930 was induced by NaCl, 4℃, 37℃, ABA, IAA and PEG.Germination percentage of At1g13930 mutant M3 was extremely lower, seedlings grew weaker, and bolting was later than wild type under Na Cl, low temperature, and high temperature stress conditions. These results showed that At1g13930 was important in tolerance to salt, heat shock or low temperature.Using the E.coli expression system, recombinant At1g13930 improved bacterial cell growth during-20℃,48 ℃and PEG treatments, suggesting that At1g13930 also played important roles in response to abiotic stresses in prokaryotes.Expression patterns of At1g13930, and predicted co-expressed genes At2g15970 and At1g06460 were analysis by qRT- PCR. The results showed that At1g13930 transcript was absent in the T-DNA insertion mutant plants. Expreesion of At1g13930 was inducible by NaCl, drought, ABA, IAA and high temperature treatments. Expression of At1g13930 and At2g15970 displayed similar patterns under NaCl and ABA treatments, the expression patterns of At1g13930 and At1g06460 were identical under high temperature treatments.