Difference between revisions of "Part:BBa K2194000"

Revision as of 00:43, 1 November 2017

chrR6 Chromate Reductase Enzyme

The chrR6 protein is a mutated/enhanced version (Tyr128Asn) of the chrR enzyme originally found in Escherichia coli. It has chromate and uranyl reductase activity.

Sequence and Features

Assembly Compatibility:

10
COMPATIBLE WITH RFC[10]
12
COMPATIBLE WITH RFC[12]
21
INCOMPATIBLE WITH RFC[21]
Illegal BglII site found at 570
23
COMPATIBLE WITH RFC[23]
25
INCOMPATIBLE WITH RFC[25]
Illegal AgeI site found at 337
1000
INCOMPATIBLE WITH RFC[1000]
Illegal BsaI site found at 3
Illegal BsaI.rc site found at 583

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 ===Usage and Biology===
+The chrR6 enzyme is a mutated/enhanced version (<sup>Tyr</sup>128<sup>Asn</sup>) of the soluble chrR enzyme originally found in <i>Escherichia coli</i> and <i>Pseudomonas putida</i>. It has chromate and uranyl reductase activity. The enzyme chrR6 reduces Cr(VI) directly to Cr(III) without producing an unstable Cr(V) intermediate and minimizing generation of toxic reactive oxygen species. [1]
+As determined from studies on purified enzymes, <sup>Tyr</sup>128<sup>Asn</sup> substitution increases the rate of Cr(VI) reduction from 295 ± 27 nmol mg protein<sup>-1</sup> min<sup>-1</sup>, as observed for chrR,  to 8,812 ± 611 nmol mg protein<sup>-1</sup> min<sup>-1</sup>. K<sub>cat</sub>/K<sub>m</sub> values are  4.5 × 10<sup>4</sup> ± 3 × 10<sup>3</sup> for chrR and 1.3 × 10<sup>7</sup> ± 3 × 10<sup>5</sup>  for chrR6. When the activity of chrR6 and chrR was studied in vivo in soil bacteria <i>P. putida</i>, no enhanced chromium or uranium reduction activity was observed for chrR6, indicating that the permeability barrier prevents the reduction activity.
+[1] Barak, Y. et al. “Analysis of Novel Soluble Chromate and Uranyl Reductases and Generation of an Improved Enzyme by Directed Evolution.” Applied and Environmental Microbiology 72.11 (2006): 7074–7082. Web.
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