Impact of CodY protein on metabolism, sporulation and virulence in Clostridioides difficile ribotype 027

Abstract

Toxin synthesis and endospore formation are two of the most critical factors that determine the outcome of infection by Clostridioides difficile. The two major toxins, TcdA and TcdB, are the principal factors causing damage to the host. Spores are the infectious form of C. difficile, permit survival of the bacterium during antibiotic treatment and are the predominant cell form that leads to recurrent infection. Toxin production and sporulation have their own specific mechanisms of regulation, but they share negative regulation by the global regulatory protein CodY. Determining the extent of such regulation and its detailed mechanism is important for understanding the linkage between two apparently independent biological phenomena and raises the possibility of creating new ways of limiting infection. The work described here shows that a codY null mutant of a hypervirulent (ribotype 027) strain is even more virulent than its parent in a mouse model of infection and that the mutant expresses most sporulation genes prematurely during exponential growth phase. Moreover, examining the expression patterns of mutants producing CodY proteins with different levels of residual activity revealed that expression of the toxin genes is dependent on total CodY inactivation, whereas most sporulation genes are turned on when CodY activity is only partially diminished. These results suggest that, in wild-type cells undergoing nutrient limitation, sporulation genes can be turned on before the toxin genes.

Diverse Energy-Conserving Pathways in Clostridium difficile: Growth in the Absence of Amino Acid Stickland Acceptors and the Role of the Wood-Ljungdahl Pathway

“…Finally, additional regulatory controls of the WLP are not unexpected. Several potential CodY-binding sites can be found in the C. difficile WLP promoter, and transcriptome sequencing (RNA-Seq) studies on cells in exponential growth, involving a panel of CodY point mutants with different levels of residual activity, show substantial increased transcription of genes throughout the WLP operon, with the largest amount (4-to 5-fold) observed in the CodY null mutant (97). Regulation in response to glucose, possibly involving CcpA or other means (65), may also be integrated with Rex and CodY in a more complex network.…”

Genome‐wide identification of Listeria monocytogenes CodY‐binding sites

“…CodY, first identified in Bacillus subtilis (Slack, Serror, Joyce, & Sonenshein, ), is a DNA‐binding protein and a global regulator of metabolism and virulence genes in nearly all low G+C Gram‐positive pathogens, including Bacillus, Clostridium, Staphylococcus, Streptococcus, Enterococcus and Listeria spp. (Brinsmade, ; Colomer‐Winter, Flores‐Mireles, Kundra, Hultgren, & Lemos, ; Daou et al, ; Geiger & Wolz, ; Li, Freedman, Evans, & McClane, ; Mlynek et al, ; Richardson, Somerville, & Sonenshein, ). The DNA‐binding affinity of CodY from B. subtilis and most other species is increased by interaction with two types of ligands, the branched‐chain amino acids (isoleucine, leucine and valine) and GTP (Han et al, ; Richardson et al, ; Sonenshein, ).…”

Tetanus Toxin Synthesis is Under the Control of A Complex Network of Regulatory Genes in Clostridium tetani

“…However, CodY indirectly represses toxin gene expression in C. difficile by interacting with the TcdR promoter [45]. Rapidly metabolizable carbohydrates such as glucose repress toxin production in C. difficile [46], and CodY is a negative regulator of toxin synthesis and virulence in this pathogen [47]. In contrast to C. difficile, TeNT synthesis in C. tetani is not inhibited by glucose.…”