Pathogen-derived enzyme engineered for antibiotic design
The World Health Organization classified the drug-resistant pathogen Acinetobacter baumannii as a critical priority for antibiotic development. One development strategy targets the production of acinetobactin, the A. baumannii siderophore, or iron chelator, that allows the pathogen to scavenge for the scarce iron nutrient inside the host. Scientists have previously determined that synthetic analogs of acinetobactin can curb bacterial growth by blocking iron uptake or inhibiting acinetobactin formation. To aid in analog production, Syed Fardin Ahmed and Andrew Gulick at the University at Buffalo wanted to leverage A. baumannii enzymes that biosynthesize acinetobactin. They published their recent work in the Journal of Biological Chemistry.

Acinetobactin biosynthesis involves an assembly line process performed by nonribosomal peptide synthetases. In these biosynthetic pathways, an adenylation domain plays a key role in substrate selectivity. The authors used available structures of the acinetobactin adenylation domain BasE to pinpoint residues to mutate in the substrate binding pocket to alter the size and allow for molecules larger than the natural substrate 2,3-dihydroxybenzoic acid. They performed enzyme activity assays and steady-state kinetic analysis to identify and characterize four BasE variants that functioned with larger substrates with efficiencies similar to the wild-type enzyme with the natural substrate.
Finally, the researchers solved the structures of three BasE variants with alternative substrates in the binding pockets. These structures confirmed visually that the mutations enlarged the binding pockets, highlighting which BasE residues contribute to accommodating specific portions of the substrate chemical structure.
Future steps will include completing a combined chemical and enzymatic synthesis of acinetobactin analogs and testing their activity for bacterial growth inhibition. The authors anticipate that their detailed investigation of BasE substrate selectivity will advance the discovery of siderophore-inspired antibiotics.
Enjoy reading ASBMB Today?
Become a member to receive the print edition four times a year and the digital edition monthly.
Learn moreGet the latest from ASBMB Today
Enter your email address, and we’ll send you a weekly email with recent articles, interviews and more.
Latest in Science
Science highlights or most popular articles

How signals shape DNA via gene regulation
A new chromatin isolation technique reveals how signaling pathways reshape DNA-bound proteins, offering insight into potential targets for precision therapies. Read more about this recent MCP paper.

A game changer in cancer kinase target profiling
A new phosphonate-tagging method improves kinase inhibitor profiling, revealing off-target effects and paving the way for safer, more precise cancer therapies tailored to individual patients. Read more about this recent MCP paper.

How scientists identified a new neuromuscular disease
NIH researchers discover Morimoto–Ryu–Malicdan syndrome, after finding shared symptoms and RFC4 gene variants in nine patients, offering hope for faster diagnosis and future treatments.

Unraveling cancer’s spaghetti proteins
MOSAIC scholar Katie Dunleavy investigates how Aurora kinase A shields oncogene c-MYC from degradation, using cutting-edge techniques to uncover new strategies targeting “undruggable” molecules.

How HCMV hijacks host cells — and beyond
Ileana Cristea, an ASBMB Breakthroughs webinar speaker, presented her research on how viruses reprogram cell structure and metabolism to enhance infection and how these mechanisms might link viral infections to cancer and other diseases.

Understanding the lipid link to gene expression in the nucleus
Ray Blind, an ASBMB Breakthroughs speaker, presented his research on how lipids and sugars in the cell nucleus are involved in signaling and gene expression and how these pathways could be targeted to identify therapeutics for diseases like cancer.