Jie Liu

General Research Interest:
My general research interests are in the area of natural products separation and isolation.
 
Roles in the NSF Project:
In this NSF project we will conduct a complete systems biology research on the regulatory and metabolic flux distribution controls of lignin biosynthesis. This project uses Populus trichocarpa (black cottonwood, the species has been sequenced) as the model species and covers a wide range of research areas, including genomics, proteomics, metabolomics, transgenics, molecular biology, biochemistry, structural and lignin chemistry, metabolic flux balance analysis and mathematical modeling.
My role in the NSF project will focus on:
 
(1) Organic synthesis of monomeric intermediate compounds associated with monolignol biosynthesis. 
Some of monomeric compounds are commercially available, for example from Sigma. But others are not commercially available, and needed to be synthesized. Some of these will also need to be synthesized with H3 label.
 
(2) Metabolic profiling.
The synthesized compounds will be used as the authentic standards to confirm and to quantify the monolignol biosynthesis intermediate compounds extracted from the developing xylem of black cottonwood, using GC-MS and LC-MS. The quantitative analysis of these extracted compounds, so called metabolic profiling, will be performed for hundreds of gene knock-downed tree samples. I will help to first establish the most effective extraction method and GC and LC separation conditions for the routine metabolic profiling analyses.
 
 (3) Enzymology.
All enzymes shown in the biosynthesis pathway will be produced as recombinant proteins from corresponding cDNAs. All cDNAs involved have cloned and already expressed many of them in yeast or E. coli for producing their recombinant proteins. Using these recombinant proteins, we will perform steady-state and enzyme inhibition kinetics to determine the feedback and feed-forward regulatory controls of metabolic flux. I may need to perform the production of recombinant proteins of a few of these pathway enzymes. The compounds I synthesized will be used as substrates for the above mentioned kinetic studies and as substrate for activity assays for proteins extracted from the developing xylem. Many of the intermediate compounds are substrates of specific pathway enzymes but also act as inhibitors (competitive and/or non-competitive) of other pathway enzymes, providing a regulatory network for the biosynthesis of monolignol at the protein level.