NF-Y transcription factors encoded by HAP gene family, composed of three subunits (HAP2/NF-YA, HAP3/NF-YB and HAP5/NF-YC), are capable of transcriptional regulation of target genes with high specificity by binding to the CCAAT-containing promoter sequences. Here, we have characterized duplicated HAP genes in Selaginella moellendorffii and explored some features that might be involved in the regulation of gene expression and their function. Subsequently, the evolutionary relationships of LEC1-type of HAP3 genes have been studied starting from lycophytes to angiosperm to reveal the details of conservation and diversification of these genes during plant evolution. Computational analyses demonstrated the variation in length of cis-regulatory region of HAP3 duplicates in S. moellendorffii containing three thermodynamically stable and evolutionarily conserved RNA secondary structures. The homology modeling of NF-Y proteins, secondary structural details, DNA binding large positive patches, binding affinity of H2A–H2B interactive residues of NF-YC subunits on the duplicated NF-YB subunits, conserved domain analyses and protein structural alignments indicated that gene duplication process of HAP genes in S. moellendorffii, followed by structural diversification, provide specific hints about their functional specificity under various circumstances for the survival of this lycophytic plant. We have identified several conserved motifs in LEC1 proteins among all plant lineages during evolution. 
In silico characterization and evolutionary analyses of CCAAT binding proteins in the lycophyte plant Selaginella moellendorffii genome: A growing comparative genomics resource