Clone and Bioinformatics Analysis of ABF Transcription Factor Gene from Nicotiana tabacum

To obtain the sequences of tobacco AREB/ABF(ABA responsive element binding proteins/ABRE binding factor) family transcription factor gene and improve tobacco's resistance to osmotic stress,the gene coding sequences of two tobacco AREB/ABF family transcription factors,NtABF1(GenBank accession number KF736849) and NtABF2(GenBank accession number KF736850),were cloned from tobacco cv.Honghuadajinyuan via sequence homology alignment and RT-PCR technique.The protein physicochemical properties,advanced structures and biological functions of the two transcription factors were predicted by bioinformatics analysis software.The results indicated that the Open Reading Frame(ORF) of NtABF1 gene was 999 bp in length,which encoded 332 amino acids with the protein molecular mass of 36.45 kDa and the isoelectric point of 9.04;the ORF of NtABF2 gene was 1305 bp in length,which encoded 433 amino acids with the protein molecular mass of 46.92 kDa and the isoelectric point of 9.35.Both NtABF1 and NtABF2 were hydrophilic proteins containing conservative structure domain Basic Region and Leucine Zipper(BRLZ),neither of them had signal peptide or transmembrane structure domain.Their advanced structure was mainly Alpha helix and random coil,the contents of Beta turn and extended strand were less.At subcellular level,both NtABF1 and NtABF2 localized in nucleus.Phosphorylation locus analysis indicated that the two proteins both contained recognition loci of Ser,Thr,Tyr kinases.The results of phylogenetic analysis and multiple sequence alignment showed that NtABF1 had closer genetic distance with AtAREB3 and their sequence similarity was 54.49%,NtABF2 had closer genetic distance with SlAREB1,StABF1 and StABF,and their sequence similarities were 83.63%,83.52% and 83%,respectively.Functional prediction results indicated that both NtABF1 and NtABF2 functioned as transcriptional regulators.