Engineering metabolism for production of unusual functional groups

Metabolic pathways leading to aromatic and aliphatic aldehydes

Aldehydes serve many useful purposes as a reactive functional group but do not naturally accumulate in common microbes. Instead, molecules containing aldehyde functional groups are rapidly converted into their corresponding alcohols. We previously engineered an E. coli strain capable of accumulation of a broad range of aromatic and aliphatic aldehydes. In initial demonstrations, we used this strain to overproduce aldehydes and also to redirect carbon flux towards other biochemical classes via aldehyde intermediates. We seek to produce broader small molecules derived from aldehydes, and we seek to generate other unusual functional groups in small molecules.

Developing more selective tools for nsAA incorporation/discrimination

Cartoon depicting quality control (kindly touched up by Dr. Jeff Ting)

Proteins are incredible polymeric nano-machines and the molecular workhorses of cells. Researchers in the chemical biology community have pioneered tools to incorporate non-standard amino acids, which are amino acids beyond the standard twenty. These molecules contain functional groups that are useful for diverse purposes. However, incorporation tools are not very selective and often lead to heterogeneity in protein synthesis. It is also very cumbersome to identify what fraction of target proteins correctly incorporated the desired non-standard amino acids. Our goal is to develop novel strategies to accurately evaluate non-standard amino acid incorporation and to use these strategies to engineer more selective incorporation tools.

Exploring novel functional groups in biopolymers and biocatalysis

Cartoon and stick representation of the ClpS binding pocket (green protein with red residues) bound to a Phe N-end peptide (yellow) (PDB ID: 3O2B)

Non-standard amino acids can endow proteins with unique functionality. Bio-orthogonal conjugation of polypeptide biomaterials is one such example, where site-specific incorporation strategies can enhance material properties and enable investigations of multivalency. We are similarly interested in exploring the role that non-standard amino acids may play in fine tuning enzymatic active sites. The development of associated design rules may aid improvement of catalytic efficiency or substrate specificity.