Abstract
The putative prenyltransferase gene ACLA_031240 belonging to the dimethylallyltryptophan synthase superfamily was identified in the genome sequence of Aspergillus clavatus and overexpressed in Escherichia coli. The soluble His-tagged protein EAW08391 was purified to near homogeneity and used for biochemical investigation with diverse aromatic substrates in the presence of different prenyl diphosphates. It has shown that in the presence of dimethylallyl diphosphate (DMAPP), the recombinant enzyme accepted very well simple indole derivatives with L-tryptophan as the best substrate. Product formation was also observed for tryptophan-containing cyclic dipeptides but with much lower conversion yields. In contrast, no product formation was detected in the reaction mixtures of L-tryptophan with geranyl or farnesyl diphosphate. Structure elucidation of the enzyme products by NMR and MS analyses proved unequivocally the highly regiospecific regular prenylation at C-5 of the indole nucleus of the simple indole derivatives. EAW08391 was therefore termed 5-dimethylallyltryptophan synthase, and it filled the last gap in the toolbox of indole prenyltransferases regarding their prenylation positions. K(m) values of 5-dimethylallyltryptophan synthase were determined for L-tryptophan and DMAPP at 34 and 76 μM, respectively. Average turnover number (k(cat)) at 1.1 s(-1) was calculated from kinetic data of L-tryptophan and DMAPP. Catalytic efficiencies of 5-dimethylallyltryptophan synthase for L-tryptophan at 25,588 s(-1)·M(-1) and for other 11 simple indole derivatives up to 1538 s(-1)·M(-1) provided evidence for its potential usage as a catalyst for chemoenzymatic synthesis.
Highlights
Known indole prenyltransferases catalyzed regioselective prenylations at N-1, C-2, C-3, C-4, C-6, and C-7 of the indole ring
We reported the identification and characterization of the first C5-prenyltransferase of indoles, i.e. 5-dimethylallyltryptophan synthase (5-DMATS) from Aspergillus clavatus and its potential usage as a catalyst for chemoenzymatic synthesis
The deduced gene product EAW08391 consists of 427 amino acids and shares high sequence similarities with C4-prenyltransferases of tryptophan, e.g. 52% identity with FgaPT2 from A. fumigatus [20] at the amino acid level
Summary
Known indole prenyltransferases catalyzed regioselective prenylations at N-1, C-2, C-3, C-4, C-6, and C-7 of the indole ring. Prenylated indole alkaloids represent a group of natural products with diverse chemical structures and are widely distributed in bacteria, fungi, plants, and marine organisms [1, 2] Because of their impressive pharmacological and biological activities as drugs or as toxins [1, 3], prenylated indole alkaloids attract the attention of scientists from different scientific disciplines, including chemistry, ecology, biology, pharmacology, and biochemistry (1, 4 –7). By the end of October 2011, 20 indole prenyltransferases from bacteria and fungi have been characterized biochemically (1, 10 –15) These enzymes catalyzed the transfer of prenyl moieties onto nitrogen or carbon atoms at the indole ring resulting in formation of “regularly” or “reversely” prenylated derivatives [15].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
