초록
<P>3-hydroxypropionic acid (3-HP) is an important platform chemical used as a precursor for production of added-value compounds such as acrylic acid. Metabolically engineered yeast, <I>Escherichia coli</I>, cyanobacteria and other microorganisms have been developed for the biosynthesis of 3-HP. Attempts to overproduce this compound in recombinant <I>Pseudomonas denitrificans</I> revealed that 3-HP is consumed by this microorganism using the catabolic enzymes encoded by genes <I>hpdH</I>, <I>hbdH</I> and <I>mmsA</I>. 3-HP-inducible systems controlling the expression of these genes have been predicted in proteobacteria and actinobacteria. In this study, we identify and characterise 3-HP-inducible promoters and their corresponding LysR-type transcriptional regulators from <I>Pseudomonas putida</I> KT2440. A newly-developed modular reporter system proved possible to demonstrate that <I>Pp</I>MmsR/P<SUB><I>mmsA</I></SUB> and <I>Pp</I>HpdR/P<SUB><I>hpdH</I></SUB> are orthogonal and highly inducible by 3-HP in <I>E. coli</I> (12.3- and 23.3-fold, respectively) and <I>Cupriavidus necator</I> (51.5- and 516.6-fold, respectively). Bioinformatics and mutagenesis analyses revealed a conserved 40-nucleotide sequence in the <I>hpdH</I> promoter, which plays a key role in HpdR-mediated transcription activation. We investigate the kinetics and dynamics of the <I>Pp</I>HpdR/P<SUB><I>hpdH</I></SUB> switchable system in response to 3-HP and show that it is also induced by both enantiomers of 3-hydroxybutyrate. These findings pave the way for use of the 3-HP-inducible system in synthetic biology and biotechnology applications.</P>