Characterization of substrate diversity in the UDP-glycosyltransferase and BAHD acyltransferase enzyme families

Plants are able to enzymatically modify compounds, which has resulted in the evolution of specialized metabolites and diversification in the plant kingdom. Two enzyme families, BAHD acyltransferases (BAHDs) and UDP-glycosyltransferases (UGTs), are involved in many such modifications. These enzymes catalyze the transfer of a “moiety” from donor to acceptor substrates, enabling more complex scaffolds. This research is a two-fold study of both families.
The first aim addresses the problem that many enzyme activities have been documented, but few are accessible in public databases. UGT activities, extracted by FuncFetch, were curated and organized by enzyme-substrate relationship. An examination of 472 papers and >1000 UGTs revealed a broad diversity of substrates that interact with the UGT family. Categorizing these enzyme-substrate relationships is the first step to creating a database that scientists can access to predict substrate compatibility for new reactions.
The second aim is to explore substrate pr

omiscuity in BAHDs–the ability to act on multiple, non-native substrates. Previous results suggest that proteins with flexible intrinsically disordered regions (IDRs) exhibit broader substrate specificity. To assess the functional significance of IDR flexibility, we engineered a more rigid IDR in AtHCT using proline to alanine mutations, and compared substrate specificity using in vitro enzyme assays. The results are inconclusive as only one tested substrate demonstrated a significant change in activity, suggesting the mutations may not be sufficient. Therefore, further mutagenesis is planned to enhance IDR rigidity. Nonetheless, these findings provide preliminary evidence that enzyme substrate specificity can be modulated by altering structural disorder.

In the Moghe lab, I was introduced to an entirely new topic in plant science: plant enzymology. At the start, I had limited biochemical knowledge, making this a challenging but rewarding experience. I definitely had imposter syndrome while struggling to understand some concepts, but the other lab members were patient and supportive. I became more comfortable asking questions–sometimes the same question twice. I learned to be observant and a thorough note-taker while shadowing my mentor during wet lab experiments. Once it came time for me to run some experiments more independently, I pushed myself to ask for help when needed. I enjoyed having the independence to run experiments, as it allowed me to challenge myself and think critically, especially when something went wrong. As the summer ends, I feel much better prepared to tackle my biochemistry course this upcoming semester. I am still uncertain about how I want to continue my journey into plant science; nevertheless, I am so grateful to NSF and BTI that I got to be a part of this lab, even for a short time.