Annotation-Based Study on Hypothetical Proteins in Bacteria Using Classification Features

Background: Hypothetical proteins (HPs) are those proteins whose functions are unknown; therefore, the present study was carried out to predict similarity-based functionality of HPs in selected bacteria Streptomyces coelicolor A3(2) and Neisseria meningitidis. Methods: Annotation-based approaches using Pfam, orthology, String, Bi-directional Best Blast Hit, PSLpred, Subloc, Cello, homology modeling, and computational tools were used in evaluating the functionality of HPs. Results: Thirty-one domains in both bacterial species were retrieved based on the E-value score and compared with bacterial species already existing in databases. Statistical analysis was duly done to check which features performed well. Conclusion: Out of 31 HPs found in Streptomyces coleicolor strain A3(2), 14 domains were found to be uncharacterized in their functionality, while 2 uncharacterized domains in the case of Neisseria meningitidis were assigned a function on similarity-based approaches. The annotation of HPs is a challenge in bacteria as these are based on the similarity of proteins in other species.