Important Insight of Hypothetical Proteins from E. faecium Strain 13-022, the Drug Targeted Virulent Big-1 Adhesins: An in-silico Approach

Background: Enterococcus faecium is an emerging multidrug resistant opportunistic pathogen responsible for causing most of the nosocomial infections. Adhesins are the cell wall anchoring proteins implicated in the pathogenesis of enterococcal infections. The present investigation is carried out to spot the occurrence of bacterial immunoglobulin-like (Ig) domain-1 or Big-1 adhesins among 204 HPs from E. faecium strain 13-022. Methods: The pathogen E. faecium chromosomal strain 13-022 was searched in the NCBI database which comprised of 2746 proteins. To filter HPs, the keyword ‘hypothetical proteins’ with sequence length >100 residues was queried. The filtered 204 HPs were subjected to functional annotation, physico-chemical properties, virulence factors, cellular location, secondary structure prediction and protein-protein interactions (PPIs). Finally, 3D models were obtained for essential non-homologous adhesins with potential drug binding pockets. Results: Primarily functional classification of 204 HPs which are assigned to 27 different functional activities with good thermal stability (50%), hydropathicity and virulence factors (79%). Majority of the HPs are predicted to reside in the cytoplasm and cell membrane. 78 HPs are predicted with high confidence. Among them, 14 are having βαβ motifs including two adhesins and the PPI network has 4 gene set of Mga helix-turn-helix and 2 gene set of putative adhesion and 77 proteins are essential hypothetical proteins (EHPs). Of 77 EHPs, 65 are pathogen-specific, indeed considered as probable drug targets. In these 65 essential pathogen specific proteins, 23 targets are found to be biological targets and rest are novel targets. Among 23 targets, three are adhesins those have therapeutic applications. Conclusion: The present study predicted the occurrence of virulent drug targeted Big-1 specifically bacterial non-pilus fimbriae immunoglobulin-like (Ig) domain-1among 204 HPs. Its structure, function and significance were emphasized to develop novel drugs for better treatment.