Non-standard amino acids (nsAAs) introduce novel chemical functionality to proteins and peptides; however, there are currently few paths to biosynthesize a diverse repertoire of nsAAs. L-threonine transaldolases (TTAs) are a recently discovered enzyme class with promise for production of aromatic nsAAs. The only two characterized TTAs catalyze the formation of beta-hydroxy-nsAAs (β-OH-nsAAs) through a stereo-selective and thermodynamically favorable condensation of L-threonine and diverse aldehydes. We have probed the substrate specificity of a characterized TTA from <i>Pseudomonas fluorescens</i> to produce novel β-OH-nsAAs. To explore the specificity of this enzyme class more broadly, we have expressed and characterized naturally occurring, putative TTAs. To characterize the broad specificity of many TTAs, we optimized a high-throughput absorbance-based assay that couples an alcohol dehydrogenase with a TTA to produce a measurable output of enzyme activity. Overall, our work helps identify new candidate enzymes that could enable biological synthesis of building blocks that expand protein functions.

Profiling of putative threonine transaldolases for biosynthesis of non-standard amino acids

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.