Use of the dehydrophos biosynthetic enzymes to prepare antimicrobial analogs of alaphosphin

• Published in: Organic & biomolecular chemistry Vol. 17; no. 4; pp. 822 - 829
• Main Authors: Bougioukou, Despina J., Ting, Chi P., Peck, Spencer C., Mukherjee, Subha, van der Donk, Wilfred A.
• Format: Journal Article
• Language: English
• Published: CAMBRIDGE Royal Soc Chemistry 23.01.2019; Royal Society of Chemistry
• Subjects: Alanine; Alanine - analogs & derivatives; Alanine - biosynthesis; Alanine - chemistry; Amino acids; Anti-Bacterial Agents - biosynthesis; Anti-Bacterial Agents - chemistry; Antibiotics; Antiinfectives and antibacterials; Antimicrobial peptides; Biocatalysis; Chemistry; Chemistry, Organic; Condensates; Derivatives; Enzymes; Ketoglutaric acid; Leucine-tRNA Ligase - metabolism; Molecular Conformation; Norleucine; Peptides; Phenylglycine; Physical Sciences; Proofreading; Science & Technology; Streptomyces - enzymology; Substrates; tRNA; ACID; AMINOACYL-TRANSFER-RNA; ANTIBACTERIAL ACTIVITY; OLIGOPEPTIDES; RHIZOCTICINS; BOND FORMATION; AGENTS; PHOSPHONOPEPTIDES; ALAFOSFALIN; PHOSPHINOTHRICIN-TRIPEPTIDE SYNTHETASES
• ISSN: 1477-0520; 1477-0539
• DOI: 10.1039/c8ob02860e

The C-terminal domain of the dehydrophos biosynthetic enzyme DhpH (DhpH-C) catalyzes the condensation of Leu-tRNA(Leu) with (R)-1-aminoethylphosphonate, the aminophosphonate analog of alanine called Ala(P). The product of this reaction, Leu-Ala(P), is a phosphonodipeptide, a class of compounds that have previously been investigated for use as clinical antibiotics. In this study, we show that DhpH-C is highly substrate tolerant and can condense various aminophosphonates (Gly(P), Ser(P), Val(P), 1-aminopropylphosphonate, and phenylglycine(P)) to Leu. Moreover, the enzyme is also tolerant with respect to the amino acid attached to tRNA(Leu). Using a mutant of leucyl tRNA synthetase that is deficient in its proofreading ability allowed the preparation of a series of aminoacyl-tRNALeu derivatives (Ile, Ala, Val, Met, norvaline, and norleucine). DhpH-C accepted these aminoacyl-tRNA(Leu) derivatives and condensed the amino acid with L-Ala(P) to form the corresponding phosphonodipeptides. A subset of these peptides displayed antimicrobial activities demonstrating that the enzyme is a versatile biocatalyst for the preparation of antimicrobial peptides. We also investigated another enzyme from the dehydrophos biosynthetic pathway, the 2-oxoglutarate dependent enzyme DhpA. This enzyme oxidizes 2-hydroxyethylphosphonate to 1,2-dihydroxyethylphosphonate en route to L-Ala(P), but longer incubation results in overoxidation to 1-oxo-2-hydroxyethylphosphonate. This alpha-ketophosphonate was converted by the pyridoxal phosphate dependent enzyme DhpD into L-Ser(P). Thus, the dehydrophos biosynthetic enzymes can generate not only L-Ala(P) but also L-Ser(P).