Expression, Purification and Metal Utilization of Recombinant Soda From Borrelia Burgdorferi
coli. Metal exchange or insertion into the Fe/Mn-SOD is inhibited in the folded state.
Other metalloproteins may have similarly adapted to using manganese as co-factor, including the BB0366 aminopeptidase. Whereas B. burgdorferi SodA has evolved in a manganese-rich, iron-poor environment, the opposite is true for Mn-SODs of organisms such as Escherichia coli and bakers' yeast. These Mn-SODs still capture manganese in an iron-rich cell, and we tested whether the same is true for Borrelia SodA. When expressed in the iron-rich mitochondria of Saccharomyces cerevisiae, B. burgdorferi SodA was inactive. Activity was only possible when cells accumulated extremely high levels of manganese that exceeded cellular iron. Moreover, there was no evidence for iron inactivation of the SOD. B. burgdorferi SodA shows strong overall homology with other members of the Mn-SOD family, but computer-assisted modeling revealed some unusual features of the hydrogen bonding network near the enzyme's active site. The unique properties of B. burgdorferi SodA may represent adaptation to expression in the manganese-rich and iron-poor environment of the spirochete.
There is currently very little information available on the tissue-specific host-pathogen interactions that lead to pathological manifestations of B. burgdorferi infection. This pathogen's ability to colonize mammals is dependent on its capacity to rapidly alter gene expression in response to highly disparate environmental signals following transmission from infected ticks (Tamborero S, Vilar M, 2011).
The method presented of acquiring a target metal under denaturing conditions may be applicable to the refolding of other metal-binding proteins.
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