Functional prediction and assignment of Clostridium botulinum type A1 operome: A quest for prioritizing drug targets

Clostridium botulinum strain Hall produces potent botulinum neurotoxin type A1, which causes food-borne, infant, and wound botulism in humans. Antibiotics and botulinum antitoxins can control growth and prevent botulinum toxicity. However, limited information on a protein with an unknown function hinders the discovery of new drug targets for this disease. In this study, a combined bioinformatics approach with literature support was applied to predict, assign, and validate operome functions. Our functional annotation scheme was based on sequence motifs, conserved domains, structures, protein folds, and evolutionary relationships. Approximately 14.62 % of the operome exhibited sequence similarity to known proteins, with 6.65 % predicted functions for 293 proteins, including 121 proteins exclusive to C. botulinum. Structural analysis revealed a significant presence of the Rossmann fold (26 %) and miscellaneous folds (43 %) among the operome. Transporters (>85) and transcriptional regulators (>45) were prevalent, underscoring their importance in C. botulinum adaptive strategies. The newly identified operome contributed to the diverse cellular and metabolic processes of this organism. The function of its operome was involved in amino acid metabolism and botulinum neurotoxin biosynthesis. In this study, we identified and characterized 13 new virulence proteins from the operome to determine their structure–function relationships. These new metabolic and virulence proteins allow the organism to colonize and interact with the human gastrointestinal tract. This study provides a quest for new drugs and targets for treating the underlying diseases of C. botulinum in humans.