# Multiple Adenylate-Forming Enzymes Contribute to Biosynthesis of the DPO Quorum-Sensing Autoinducer

## TL;DR

This paper reveals how bacteria make a signaling molecule called DPO using multiple enzymes, without a single dedicated enzyme.

## Contribution

The study identifies that various adenylate-forming enzymes collectively contribute to DPO biosynthesis in Vibrio cholerae.

## Key findings

- DPO is synthesized from aminoacetone and alanine via alanyl-adenylate intermediates.
- Multiple adenylate-forming enzymes can produce alanyl-adenylate, a key step in DPO biosynthesis.
- DPO biosynthesis lacks a dedicated synthase, relying instead on a collection of enzymes.

## Abstract

Bacteria use a process
of chemical communication called quorum
sensing to regulate group behaviors. Quorum sensing relies on the
synthesis, release, and detection of signal molecules called autoinducers
that accumulate with increasing cell density. The pathogen Vibrio cholerae makes and detects three autoinducers which
together, regulate genes required for group behaviors including virulence
and biofilm formation. Two autoinducers are produced by dedicated
autoinducer synthases that employ S-adenosyl methionine
as a substrate. The third autoinducer, 3,5-dimethylpyrazin-2-ol (DPO),
is produced from threonine and alanine. The threonine dehydrogenase
(Tdh) enzyme oxidizes l-threonine to 2-amino-3-ketobutyric
acid, which spontaneously decarboxylates to aminoacetone. Here, we
define the steps required to convert aminoacetone and alanine into
DPO. We show that diverse adenylate-forming enzymes can condense ATP
and d- or l-alanine to form alanyl-adenylate, the
necessary intermediate in DPO biosynthesis. Upon release, alanyl-adenylate
spontaneously condenses with aminoacetone to form N-alanyl-aminoacetone, which cyclizes to form DPO. We propose that
DPO is distinct from other autoinducers in that there is apparently
no dedicated synthase. Rather, a collection of enzymes contribute
to the production of this quorum-sensing autoinducer.