https://www.selleckchem.com/products/Pyroxamide(NSC-696085).html Streptococcus sanguinis is an oral commensal bacterium, but can colonize pre-existing heart valve vegetations if introduced into the blood stream, leading to infective endocarditis. Loss of Mn- or Fe-cofactored virulence determinants are thought to result in enfeeblement of this bacterium. Indeed, intracellular Mn accumulation mediated by the lipoprotein SsaB, a component of the SsaACB transporter complex, has been shown to promote virulence for endocarditis and O2 tolerance. To delineate intracellular metal-ion abundance and redox speciation within S. sanguinis, we developed a protocol exploiting two spectroscopic techniques, Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) and Electron Paramagnetic Resonance (EPR) spectroscopy, to respectively quantify total intracellular metal concentrations, and directly measure redox speciation of Fe and Mn within intact whole-cell samples. Addition of the cell-permeable siderophore deferoxamine shifts the oxidation states of accessible Fe and Mn from reduced-to-oxidized, as verified by magnetic moment calculations, aiding in the characterization of intracellular metal pools and metal sequestration levels for Mn2+ and Fe. We have applied this methodology to S. sanguinis and an SsaACB knockout strain (ΔssaACB), indicating that SsaACB mediates both Mn and Fe uptake, directly influencing the metal-ion pools available for biological inorganic pathways. Mn-supplementation to ΔssaACB returns total intracellular Mn to wild-type levels, but does not restore wild-type redox speciation or distribution of metal cofactor availability for either Mn or Fe. Our results highlight the biochemical basis for S. sanguinis oxidative resistance, revealing a dynamic role for SsaACB in controlling redox homeostasis by managing the intracellular Fe/Mn composition and distribution.Fuel-free light-driven micromotors have attracted increasing attention since the advantages