Anatomical Site-Specific Carbohydrate Availability Impacts Streptococcus pneumoniae Virulence and Fitness during Colonization and Disease

Abstract

Streptococcus pneumoniae ( Spn ) colonizes the nasopharynx asymptomatically but can also cause severe life-threatening disease. Importantly, stark differences in carbohydrate availability exist between the nasopharynx and invasive disease sites, such as the bloodstream, which most likely impact Spn ’s behavior. Herein, using chemically-defined media (CDM) supplemented with physiological levels of carbohydrates, we examined how anatomical-site specific carbohydrate availability impacted Spn physiology and virulence. Spn grown in CDM modeling the nasopharynx (CDM-N) had reduced metabolic activity, slower growth rate, demonstrated mixed acid fermentation with marked H 2 O 2 production, and were in a carbon-catabolite repression (CCR)-derepressed state versus Spn grown in CDM modeling blood (CDM-B). Using RNA-seq, we determined the transcriptome for Spn WT and its isogenic CCR deficient mutant in CDM-N and CDM-B. Genes with altered expression as a result of changes in carbohydrate availability or catabolite control protein deficiency, respectively, were primarily involved in carbohydrate metabolism, but also encoded for established virulence determinants such polysaccharide capsule and surface adhesins. We confirmed that anatomical site-specific carbohydrate availability directly influenced established Spn virulence traits. Spn grown in CDM-B formed shorter chains, produced more capsule, were less adhesive, and were more resistant to macrophage killing in an opsonophagocytosis assay. Moreover, growth of Spn in CDM-N or CDM-B prior to the challenge of mice impacted relative fitness in a colonization and invasive disease model, respectively. Thus, anatomical site-specific carbohydrate availability alters Spn physiology and virulence, in turn promoting anatomical-site specific fitness.

Targeting NAD+ regeneration enhances antibiotic susceptibility of Streptococcus pneumoniae during invasive disease

“…Carbon availability has been shown to influence the 3 fermentation pathways and the production of pneumococcal virulence determinants [25], especially capsular polysaccharide [24]. We observed that all Spn mutants in our panel produced significantly less capsular polysaccharide than WT.…”

“…Doubling time was not impaired once bacteria reached exponential phase, with ΔpdhC observed to replicate faster than WT. Importantly, all of the revertant strains had phenotypes equivalent to WT, indicating that observations made with our mutants were not due to off-target effects (S1 Fig) . Finally, to further dissect the divergence between the observed extended lag phase and unimpaired exponential phase of our mutants, we measured metabolic activity using heat flow [24]. With exception to the ldh mutant, none of the mutants in our panel displayed changes in…”

A Jack of All Trades: The Role of Pneumococcal Surface Protein A in the Pathogenesis of Streptococcus pneumoniae

“…pspA expression was repressed when the response regulator RR06 was phosphorylated and overexpressed (Standish et al, 2007). A recent report by Im et al also showed pspA gene expression is influenced by carbon-catabolite repression and nutrient availability (Im et al, 2021). Altogether, one can infer that the regulation of pspA is multifaceted and complex.…”

“…A recent report by Im et al. also showed pspA gene expression is influenced by carbon-catabolite repression and nutrient availability ( Im et al., 2021 ). Altogether, one can infer that the regulation of pspA is multifaceted and complex.…”

Pn-AqpC-Mediated Fermentation Pattern Coordination with the Two-Component System 07 Regulates Host N-Glycan Degradation of Streptococcus pneumoniae

“…The capability to catabolize these sugars enables pneumococcus to survive in distinct host niches and invade into hosts ( 12 , 13 ). Therefore, the regulatory mechanisms in carbohydrate metabolism play important roles in the transition of pneumococcus from commensal to pathogenic status ( 14 ).…”