Structural and functional characterization of nac transcription factor genes in artemisia annua using computational approaches

The Transcription factors act as key regulatory switches of transcription networks and gene expressivity level. The plant specific NAC transcription factor is derived from no apical meristem (NAM), Arabidopsis transcription activation factor (ATAF) and cup-shaped cotyledon (CUC) superfamily. It has crucial regulatory roles against various abiotic stresses and hormone signalling. In Artemisia annua 28 NAC genes were retrieved from PlnTFDB; Plant Transcription Factor Database and protein sequences were obtained by using ExPaSy server and analyzed by various insilico applications. Homology search of these proteins was done by employing The NCBI BLAST tool which revealed the higher similarity percentage with homologous; mainly of members of the Asteraceae family. Sequences were further studied for phylogenetic analysis and motif identification. Results of the NCBI CDD server and clustal W suggested that in majority of AaNAC proteins, presence of NAM domains was confirmed except in AaNAC12 and AaNAC27. In some proteins, harboring signature NAM domain, gap sequences were observed between Nto Cterminus which were also conserved in nature. Multiple sequence alignment of proteins was used for phylogenetic analysis. At 1000 bootstrapping the 28 members were grouped in 2 clusters and 7 groups. Cis-regulatory domains were analyzed by Plant Care and PLACE tools, from where the presence of TATA, CAAT, TCC boxes and binding sites for MYB, MYC, ARE and other transcriptional regulators were observed. A multilevel consensus sequence of conserved motifs from all the NAC protein members of A. annua was retrieved by employing MEME suit. Out of 10, 1st and 2nd conserved motifs were found to cover the NAM domain. For the analysis of physical characters, the NAC members were studied for molecular weight, acidicbasic, polarnonpolar behaviour and localization. All members share some common features like nonpolar behaviour, nuclear localization and absence of any transmembrane domain.