|
type |
Journal Article |
authors |
Milbredt D, Patallo EP, van Pée KH. |
title |
Characterization of the Aminotransferase ThdN from Thienodolin Biosynthesis in Streptomyces albogriseolus. |
journal |
Chembiochem. |
Activity |
thnj |
Family |
thnj |
sel |
selected |
ui |
27531243 |
year |
(2016) |
volume |
17 |
number |
19 |
pages |
1859-1864 |
| |
abstract |
In Streptomyces albogriseolus the indolethiophen alkaloid thienodolin is derived from tryptophan. The first step in thienodolin biosynthesis is the regioselective chlorination of tryptophan in the 6-position of the indole ring. The second step is catalyzed by the aminotransferase ThdN. ThdN shows sequence homology (up to 69 % similarity) with known pyridoxal 5'-phosphate-dependent aminotransferases of the aspartate aminotransferase family from Gram-positive bacteria. thdN was heterologously expressed in Pseudomonas fluorescens, and the enzyme was purified by nickel-affinity chromatography. ThdN is a homodimeric enzyme with a mass of 90 600 kDa and catalyzes the conversion of l-tryptophan and a number of chlorinated and brominated l-tryptophans. The lowest KM values were found for 6-bromo- and 6-chlorotryptophan (40 and 66 μm, respectively). For l-tryptophan it was 454 μm, which explains why thienodolin is the major product and dechlorothienodolin is only a minor component. The turnover number (kcat ) for 7-chlorotryptophan (128 min-1 ) was higher than that for the natural substrate 6-chlorotryptophan (88 min-1 ). |
last changed |
2018/03/27 10:07 |
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