A Tryptophan Prenyltransferase with Broad Substrate Tolerance from Bacillus subtilis subsp. natto.

Bacillus subtilis subsp. natto secretes the ComXnatto pheromone as a quorum-sensing pheromone to produce poly-γ-glutamate for biofilm formation. The amino-acid sequence of the pheromone is Lys-Trp-Pro-Pro-Ile-Glu, and the tryptophan residue is post-translationally modified with a farnesyl group to form a tricyclic scaffold. Unlike other Bacillus ComX pheromones, the tryptophan residue is distant from the C-terminal end of the precursor peptide ComXnatto . Here, we report the functional analysis of ComQnatto , which catalyzes a unique farnesyl-transfer reaction. ComQnatto recognizes not only full-length ComXnatto but also N- and/or C-terminal truncated ComXnatto analogues and even a single tryptophan for modification with a farnesyl group in vitro. These results, together with the calculated kinetic parameters, suggest that ComQnatto does not require a leader sequence for substrate recognition and is a promising enzyme with broad substrate tolerance for the synthesis of various prenylated tryptophan derivatives.