Bioinformatics analysis of extracellular subtilisin E from <i>Bacillus subtilis</i>

<i>Bacillus</i> spp. are the main sources of subtilisin E, which has several applications in biotechnology. The 3D structure of subtilisin E has a significant impact on its efficacy. In this study, we evaluated subtilisin E from <i>Bacillus subtilis</i> subsp. <i>subtilis</i> str. 168 by bioinformatic methods. The results revealed that the subtilisin E sequence from <i>B. subtilis</i> contains highly conserved amino acids, including histidine (H), aspartic acid (D) and serine (S). Subtilisin E cleaves the bonds between hydrophobic and polar amino acids in keratin-associated proteins. The effects of point mutations on the crystal structure of subtilisin E (PDB ID: 1SCJ) showed that changes of asparagine 123 (N123) to valine (V) and serine 331 (S331) to leucine (L) respectively, were the most stabilizing. Genomic analysis of the subtilisin E-coding gene (<i>aprE</i>) indicated that this gene and the <i>yhfN</i> gene are expressed through a σA promoter. The analysis of TBFs revealed AbrB, ScoC, DegU, Hpr, σA, SinR, TenA, and DegU as relevant regulators of <i>aprE</i> expression. Phylogenetic analysis showed that subtilisin Es have highly conserved structures among <i>Bacillus</i> spp., sharing a common ancestor, where their coding genes were duplicated and evolved within the <i>Bacillus</i> spp. As the conclusion, our <i>in silico</i> study demonstrated that the overexpression of the <i>aprE</i> gene and stability of the produced subtilisin E can be improved though system biology methods such as point mutations and identifying the involved transcription factors (TFs) or/and TBFs. Communicated by Ramaswamy H. Sarma