ArcR modulates biofilm formation in the dental plaque colonizer Streptococcus gordonii

Abstract

Biofilm formation and cell-cell sensing by the pioneer dental plaque colonizer Streptococcus gordonii are dependent upon arginine. This study aimed to identify genetic factors linking arginine-dependent responses and biofilm formation in S. gordonii. Isogenic mutants disrupted in genes required for the biosynthesis or catabolism of arginine, or for arginine-dependent gene regulation, were screened for their ability to form biofilms in a static culture model. Biofilm formation by a knockout mutant of arcR, encoding an arginine-dependent regulator of transcription, was reduced to < 50% that of the wild-type whereas other strains were unaffected. Complementation of S. gordonii ∆arcR with a plasmid-borne copy of arcR restored the ability to develop biofilms. By DNA microarray analysis, 25 genes were differentially regulated in S. gordonii ∆arcR compared with wild-type under arginine-replete conditions including eight genes encoding components of phosphotransferase systems for sugar uptake. By contrast, disruption of argR or ahrC genes, which encode paralogous arginine-dependent regulators, each resulted in significant changes in the expression of more than 100 genes. Disruption of a gene encoding a putative extracellular protein that was strongly regulated in S. gordonii ∆arcR had a minor impact on biofilm formation. We hypothesize that genes regulated by ArcR form a critical pathway linking arginine sensing to biofilm formation in S. gordonii. Further elucidation of this pathway may provide new targets for the control of dental plaque formation by inhibiting biofilm formation by a key pioneer colonizer of tooth surfaces.

Transcriptome, Phenotypic, and Virulence Analysis of Streptococcus sanguinis SK36 Wild Type and Its CcpA-Null Derivative (ΔCcpA)

“…When analyzed the down regulated DEGs, we found a subset of genes, argB, argC, argG, argH, and argJ, all of these arg genes were associated with arginine biosynthesis. Many studies have reported the association between the arginine metabolism and biofilm development in S. sanguinis (Zhu et al, 2017; Nascimento et al, 2019), Streptococcus gordonii (Robinson et al, 2018) , S. aureus and S. mutans (Zhu et al, 2007; Sharma et al, 2014; Huang et al, 2017). Furthermore, another subset of regulated DEGs, comD, comEC, and comX related to the genetic competence system, can also influence biofilm formation which have been reported in S. mutans (Li et al, 2001; Aspiras et al, 2004; Perry et al, 2009).…”

Transcriptional profiling of coaggregation interactions between Streptococcus gordonii and Veillonella parvula by Dual RNA-Seq

“…Components of a PTS for mannose, sorbose or fructose (SGO_0044–0046) were down-regulated in response to coaggregation. This system has previously been shown to be under the control of the arginine-sensing regulators ArgR and AhrC 44 . However, there was no evidence for a global arginine-sensing response in S. gordonii and arginine biosynthesis genes were not regulated in response to coaggregation.…”

Interactions Between Streptococcus gordonii and Fusobacterium nucleatum Altered Bacterial Transcriptional Profiling and Attenuated the Immune Responses of Macrophages

“…The arginine repressor is responsible for suppressing arginine deiminase pathways in S. gordonii, and the gene that encodes arginine repressor (SGO_RS03435) was up-regulated (1.58-fold change) (Jakubovics et al, 2015;Robinson et al, 2018). arcA (SGO_RS07805), encoding arginine deiminase, was downregulated (-2.60-fold change).…”