My Research

In my research I work with a plant known as Artemisia annua. This plant is the sole biological source for the active anti-malarial drug qing hao su (ching-how-soo), or, artemisinin, as it is known outside of China. At times, limitations to the availability and accessibility of this drug threatens the prevention and treatment of malaria. One of these limitations is that A. annua does not produce artemisinin in high or uniform quantities. Thus, research on metabolic engineering, like the kind done in my lab (Deyu Xie, North Carolina State University) is important for establishing plant cultivars capable of producing high levels of artemisinin. 

My work specifically focuses on a suite of enzymes that are well-known across the animal, plant and fungal kingdoms. These enzymes are important for the synthesis of many significant molecules, including artemisinin. The specific enzymes that I study are Cytochrome P450 71AV1 (CYP71AV1) and its enzymatic partners from the artemisinin biosynthetic pathway. The interactions between these enzymes are critical because they catalyze several steps along the biosynthetic pathway to produce a series of oxygenated molecules. Previous research has identified Cytochrome P450 Reductase (CPR1) as a functional partner of CYP71AV1. Other work proposes that Cytochrome b5 (CYB5) is another interacting partner based on its presence in the plant genome and the fact that CYB5 enzymes from different biological systems associate with CYPs. In addition to these enzymes, another CPR enzyme has been identified as a possible interacting partner of CYP71AV1 based on gene sequence homology to CPR1. This enzyme is classified as CPR2. I intend to uncover the true nature of CPR2's functionality, including whether it interacts with CYP71AV1 to make artemisinin. 

The primary mechanism behind these enzyme interactions is an electron transfer from one enzyme to the next. Electron transfers can introduce bottlenecks into a biosynthetic pathway, especially if they are inefficient (enzymes do not partner effectively, or electrons are consumed by other co-factors/enzymes). Thus, uncovering the intricacies of enzyme partnerships such as that between CYP71AV1 and CPRs/CYB5 will be invaluable to the advancement of metabolic engineering. My research intends to interrogate the specificities of the partnership between CYP71AV1 and its redox enzymes to generate important kinetic and thermodynamic data that will inform metabolic engineering strategies.

Publications

Below are a list of publications relevant to my research, both from my lab (Xie Laboratory, North Carolina State University) and other institutions. My own publications will later be included here.

Artemisinin biosynthesis in Artemisia annua and metabolic engineering: questions, challenges, and perspectives

External Research

This review paper from my lab outlines the history of the anti-malarial drug artemisinin, including its mode of action against malaria parasites, its implementation as a treatment, and the elucidation of its biosynthetic pathway. A discussion on genetic breeding of Artemisia annua plants for increased artemisinin production and metabolic engineering strategies (including synthetic techniques) is also included.

A Genome-wide scenario of terpene pathways in self-pollinated Artemisia annua

External Research

This paper from my lab outlines the various important regulatory networks, genes, and proteins that function to generate artemisinin and its derivatives. This paper mentions the cytochrome P450 reductase homolog (CPR2) that I am working to characterise.

Cytochrome P450 enzymes: A driving force of plant diterpene diversity

External Research

This review paper provides a summary of plant Cytochrome P450 (CYP) enzymes and their significance in plant secondary metabolism. It is worth noting that diterpenes are large molecules that contain 20 carbon atoms and artemisinin is classified as a sesquiterpene, meaning it only has 15 carbon atoms. While some differences therefore may prevail regarding the synthesis of these molecules, the overall function, evolution, and diversity of CYP enzymes remains the same.

A large-scale comparative analysis of affinity, thermodynamics and functional characteristics of interactions of twelve cytochrome P450 isoforms and their redox partners

External Research

To get a sense of some of the techniques I hope to include in my own research I have included a paper that details the use of super plasmon resonance (SPR) to address the different kinetic and thermodynamic properties that exist for CYP enzymes and their partner enzymes (such as Cytochrome P450 Reductases).