Examination of the Clostridioides (Clostridium) difficile VanZ ortholog, CD1240

Abstract

Clostridioides (Clostridium) difficile causes severe diarrheal disease that is directly associated with antibiotic use and resistance. Although C. difficile demonstrates intrinsic resistance to many antimicrobials, few genetic mechanisms of resistance have been characterized in this pathogen. In this study, we investigated the putative resistance factor, CD1240 (VanZ1), an ortholog of the teicoplanin resistance factor, VanZ, of Enterococcus faecium. In C. difficile, the vanZ1 gene is located within the skin element of the sporulation factor σ, which is excised from the mother cell compartment during sporulation. This unique localization enabled us to create a vanZ1 deletion mutant by inducing excision of the skin element. The Δskin mutant exhibited moderately decreased resistance to teicoplanin and had small effects on growth in some other cell-surface antimicrobials tested. Examination of vanZ1 expression revealed induction of vanZ1 transcription by the antimicrobial peptide LL-37; however, LL-37 resistance was not impacted by VanZ1, and none of the other tested antimicrobials induced vanZ1 expression. Further, expression of vanZ1 via an inducible promoter in the Δskin mutant restored growth in teicoplanin. These results demonstrate that like the E. faecium VanZ, C. difficile VanZ1 contributes to low-level teicoplanin resistance through an undefined mechanism.

VanZ Reduces the Binding of Lipoglycopeptide Antibiotics to Staphylococcus aureus and Streptococcus pneumoniae Cells

“…Surprisingly, when expressed in S. aureus, enterococcal genomic vanZ g , which is not associated with any glycopeptide resistance gene cluster, was more efficient in conferring resistance to TEI than vanZ Tei ( Table 1). In addition to E. faecium and S. pneumoniae, the involvement of genomic vanZ genes in the resistance to lipoglycopeptide antibiotics was reported for orthologs from Streptococcus suis and Clostridium difficile (Lai et al, 2017;Woods et al, 2018; Supplementary Figure S2). In addition to resistance, VanZ proteins might play a more general role in stress response and virulence, as it was observed that the expression of the streptococcal vanZ gene was induced by the epithelial antimicrobial peptide LL37 (Lai et al, 2017) and ribosome-targeting antibiotics (Ng et al, 2003) or was essential for lung infection (Hava and Camilli, 2002).…”

Molecular mechanisms of vancomycin resistance

“…The corresponding VanZ F protein shared 21% primary sequence identity with VanZ A but the significance of this protein in the resistance cascade remains unknown. In Clostridiodes difficile a VanZ homologue CD1240 (38% identity to VanZ A ) is encoded on the chromosome outside the van regulon and was shown to be required for resistance to teicoplanin but not to vancomycin . These three VanZ orthologs belong to the “VanZ superfamily” (PF04892 in Pfam), which comprises 7,428 sequences present in Firmucutes (Bacilli, Clostridia, Proteobacteria and Bacteroidetes) and Actinobacteria.…”

“…In Clostridiodes difficile a VanZ homologue CD1240 (38% identity to VanZ A ) is encoded on the chromosome outside the van regulon and was shown to be required for resistance to teicoplanin but not to vancomycin. 71 These three VanZ orthologs belong to the "VanZ superfamily" (PF04892 in Pfam), which comprises 7,428 sequences present in Firmucutes (Bacilli, Clostridia, Proteobacteria and Bacteroidetes) and Actinobacteria. While the majority of these proteins are comprised of VanZ sequence exclusively, some representatives combine the VanZ sequence with RDD domain (PF06271), which is a domain also of unknown function.…”

Phylogenomic analysis ofClostridiodes difficileribotype 106 strains reveals novel genetic islands and emergent phenotypes

“…GI1 possesses several gene attributes that may confer competitive advantage to the RT106 clade. It harbors a vanZ allele, distinct from vanZ1 (49% identity) present elsewhere in RT106 genome and in other C. difficile strains including the well-studied 630 (57). In 630, VanZ1 was previously shown to confer low level resistance to the glycopeptide antibiotic, teicoplanin, but not to vancomycin (57).…”

“…It harbors a vanZ allele, distinct from vanZ1 (49% identity) present elsewhere in RT106 genome and in other C. difficile strains including the well-studied 630 (57). In 630, VanZ1 was previously shown to confer low level resistance to the glycopeptide antibiotic, teicoplanin, but not to vancomycin (57). The presence of a second VanZ allele may contribute to the modest increase in teicoplanin resistance of RT106 strains.…”