Tellurite and Tellurate Reduction by the Aerobic Anoxygenic Phototroph Erythromonas ursincola, Strain KR99 Is Carried out by a Novel Membrane Associated Enzyme

• Published in: Microorganisms
• Main Authors: Chris Maltman, Lynda J. Donald, Vladimir Yurkov
• Format: Article in Journal/Newspaper
• Language: English
• Published: MDPI AG 2017
• Subjects: tellurite; tellurate; tellurium; reduction; aerobic anoxygenic phototroph; Biology (General); QH301-705.5; Kamchatka
• Online Access: https://doi.org/10.3390/microorganisms5020020; https://doaj.org/article/26ea41780b62473c93d09ce4bb945721

Erythromonas ursincola, strain KR99 isolated from a freshwater thermal spring of Kamchatka Island in Russia, resists and reduces very high levels of toxic tellurite under aerobic conditions. Reduction is carried out by a constitutively expressed membrane associated enzyme, which was purified and characterized. The tellurite reductase has a molecular weight of 117 kDa, and is comprised of two subunits (62 and 55 kDa) in a 1:1 ratio. Optimal activity occurs at pH 7.0 and 28 °C. Tellurite reduction has a Vmax of 5.15 µmol/min/mg protein and a Km of 3.36 mM. The enzyme can also reduce tellurate with a Vmax and Km of 1.08 µmol/min/mg protein and 1.44 mM, respectively. This is the first purified membrane associated Te oxyanion reductase.