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

Chris Maltman; Lynda J Donald; Vladimir Yurkov

doi:10.3390/microorganisms5020020

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

Microorganisms. 2017 Apr 19;5(2):20. doi: 10.3390/microorganisms5020020.

Authors

Chris Maltman¹, Lynda J Donald², Vladimir Yurkov³

Affiliations

¹ Department of Microbiology, University of Manitoba, Winnipeg, MB R3T 2N2, Canada. ummaltma@myumanitoba.ca.
² Department of Microbiology, University of Manitoba, Winnipeg, MB R3T 2N2, Canada. lynda.donald@umanitoba.ca.
³ Department of Microbiology, University of Manitoba, Winnipeg, MB R3T 2N2, Canada. vyurkov@umanitoba.ca.

Abstract

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 V_max of 5.15 µmol/min/mg protein and a K_m of 3.36 mM. The enzyme can also reduce tellurate with a V_max and K_m of 1.08 µmol/min/mg protein and 1.44 mM, respectively. This is the first purified membrane associated Te oxyanion reductase.

Keywords: aerobic anoxygenic phototroph; reduction; tellurate; tellurite; tellurium.