RECONSTRUCTION AND ANALYSIS OF THE TRANSCRIPTOME REGULATORY NETWORK OF CLOSTRIDIUM BOTULINUM TYPE A3 STR. LOCH MAREE

Abstract

Clostridium botulinum type A3 str. Loch Maree is a clinically important strain that produces botulinum neurotoxin type A3 and causes foodborne, infant, and wound botulism worldwide. Studying the mechanism underlying the virulence of this organism is imperative to understand its antibacterial resistance and discovering new drugs or inhibitors. The biochemical and molecular characteristics of this organism have been intensively studied, but their gene regulatory mechanisms are unclear. Hence, we reconstructed the transcriptional regulatory network from the complete genome of this organism and analyzed interactive genes from the identified hub module using a knowledge-based bottom-up approach. The biological reliability, topological properties, and robustness of the regulatory network model were validated with network parameters, followed by gene ontology terms and literature support. The reconstructed regulatory network consisted of 12 transcriptional regulators associated with 2369 coding genes. ResD, SpoOA, ComK, CcpC, DinR, DegU, CitT, CodY, GerE, GltC, GltR, IolR, and LevR were identified as transcriptional regulators from this organism homologous to Bacillus subtilis 168. These regulators have been shown to control beta-lactamase, methyl-accepting chemotaxis protein, DNA replication protein DnaD, sensor histidine kinase, and putative membrane proteins of this organism. This study also predicted all possible promoter sites in regulated genes and their associated molecular functions. We conclude that a global regulatory network model of this organism provides insights into its growth physiology and virulence elicitation in the human intestinal environment.