Journal: Microbiology Spectrum

Article Title: The PdxR-PdxKU locus involved in vitamin B 6 salvage is important for group A streptococcal resistance to neutrophil killing and survival in human blood

doi: 10.1128/spectrum.01609-24

Figure Lengend Snippet: PdxR represses pdxR and induces pdxKU transcription in the absence of vitamin B 6 precursors. Firefly luciferase ( luc ) reporter fusions to either ( A ) P pdxR (blue) or ( B ) P pdxKU (green) promoters in WT (5448, black) or ∆pdxR GAS grown in CDM-3 (No B6) or CDM-1 (+B6). Data are expressed as relative light units (RLU). Statistics for A and B were determined by Brown-Forsythe and Welch ANOVA with Dunnett’s T3 test for multiple comparisons. Comparisons shown are to WT with No B 6 (* P < 0.05) ( C ) qRT-PCR of pdxK transcript levels in WT (5448, black), ∆pdxR mutant (blue), and complemented (light blue) strains grown in THY and shocked in CDM-3 (No B6) or CDM-1 (+B6). Data are reported as 2^(-ΔΔCt) relative WT in no B6 with gyrA as an internal control. Statistical significance was tested with two-way ANOVA and Tukey’s multiple comparisons test. Comparisons shown are to WT with No B 6 (*** P < 0.001, **** P < 0.0001).

Article Snippet: Liquid cultures were grown in Todd-Hewitt medium with 0.2% yeast extract (THY), chemically defined medium (CDM) lacking carbohydrates (CDM-1, Alpha Biosciences) supplemented with 0.5% glucose or custom CDM lacking pyridoxal, pyridoxamine, and carbohydrates (CDM-3, Alpha Biosciences) supplemented with 0.5% glucose.

Techniques: Luciferase, Quantitative RT-PCR, Mutagenesis, Control