Research On Protein Acetylation Modification Of Nostoc Flagelliforme In Response To Drought Stress

Nostoc flagelliforme is a kind of terrestrial cyanobacteria with strong drought tolerance,which grows in the arid or semi-arid desert steppe in China.In this study,Label free,LC-MS/MS and other techniques were employed to analyze the acetylated expression profile of N.flagelliforme under different levels of drought stress.The bioinformatics technology was used to analysis of acetylated peptides with differential expression of acetylated proteins in response to drought stress,The motif sequence,GO functional annotation and KEGG pathway significant enrichment were analyzed.In addition,the acetylated proteins that were differentially expressed in response to drought stress were verified by qRT-PCR and physiological experiments.The biological function and its involved metabolic pathways of acetylation protein of N.flagelliforme in response to drought stress were also analyzed.The study obtained the following results:1.A total of 1608 acetylation sites,1340 acetylated peptides and 653 acetylated proteins were identified of N.flagelliforme under drought stress.In all acetylated peptides,90.0%of peptides ranged in length from 5 to 19 amino acids,and 10.0%of peptides were more than 19 amino acids in length.2.11 conserved motif sequences were obtained through bioinformatics analysis.The K,R,and E amino acid residue sequences of Lysine was more likely to undergo acetylation.3.GO functional annotation and KEGG pathway analysis showed that the acetylated proteins of N.flagelliforme were involved in biological processes such as glutathione metabolism,energy metabolism,and photosynthesis.4.Under the continuous drought stress conditions,the transcriptional levels of GST,pepA,psaB,petH,pgk,PDH,TAL2,fbp,TKL and GAPDH genes indicted that increasing first and then decreasing.The transcriptional level of BKT,atpH,ParA,ICDHc,SDH gene showed a trend of increasing first,then decreasing,and then increasing again.The transcriptional levels of atpA,a-KGDH and DLD genes showed a trend of decreasing first and then increasing.The transcriptional levels of PRK gene shows increased first,after that decreased slightly,and then increased.5.Under the continuous drought stress conditions,the activities of GST,a-KGDH,PDH,ICDH,SDH,GAPDH were decreased,but activities of FBP were increased.The activity of PGK reached its maximum activity when the water loss rate was 80%,but the activity decreased when the water loss rate is 100%.Superoxide dismutase(SOD)and peroxidase(POD)showed a decreased trend.The activities of glutathione reductase and sucrose phosphate synthetase showed a gradual increased.6.Under the continuous drought stress conditions,the contents of reducing glutathione,pyruvic acid,soluble sugar,glucose,fructose sucrose,and trehalose were gradually increased.7.The glutathione-related enzymes of N.flagelliforme occurs differential expression of acetylated,and energy metabolism-related proteins are regulated by acetylation levels.