We use the combination of organic and enzymatic strategies to generate the repository of mammalian glycans and glycopeptides, and employ these structures to develop glycomics tools to study carbohydrate-protein interactions and glycosylation alteration. We also use molecular biology, biochemistry, and chemical biology technologies to understand the biosynthesis of bacterial glycans and glycoconjugates with a focus on antibiotic-resistant pathogens Pseudomonas aeruginosa and Clostridioides difficile.

1. Streamline the Synthesis of Complex Glycans and Glycoconjugates

Carbohydrates are directly involved in normal physiology and in the etiology of every major disease afflicting mankind. Elucidation of their functions and the mechanism of related biological processes demands diverse structurally well-defined glycoforms. Owning to the inherent complexity and diversity, isolation of natural glycans in sufficient amounts remains a formidable challenge, and synthesis of complex glycans with designated linkages continues to pose difficulties despite recent advances in the field. Takes advantage of organic chemistry in gram scale synthesis of glycan core structures, and the stereo- and regio-selectivity of enzymatic synthesis, we are developing chemoenzymatic approaches to streamline the production of complex glycans, with a focus on N-glycans, N-glycopeptides, O-glycans, O-glycopeptides, and glycosaminoglycans.

Related Publications

Congcong Chen, Shuaishuai Wang, Madhusudhan Reddy Gadi, He Zhu Fei Liu, Chang-Cheng Liu, Lei Li*, Fengshan Wang*, Peixue Ling* & Hongzhi Cao*. Enzymatic modular synthesis and microarray assay of poly-N-acetyllactosamine derivatives. Chem Commun, 2020, 56, 7549-7552.

Shuaishuai Wang, Qing Zhang, Congcong Chen, Yuxi Guo, Madhusudhan Reddy Gadi, Jin Yu, Ulrika Westerlind, Yunpeng

Liu, Xuefeng Cao, Peng G. Wang* & Lei Li*. Facile chemoenzymatic synthesis of O-mannosyl glycans. Angew Chem Int Ed, 2018, 57, 9268-9273.

Lei Li, Yunpeng Liu, Cheng Ma, Jingyao Qu, Angie D. Calderon, Baolin Qu, Na Wei, Xuan Wang, Yuxi Guo, Zhongying Xiao, Jing Song, Go Sugiarto, Yanhong Liu, Hai Yu, Xi Chen & Peng G. Wang. Efficient chemoenzymatic synthesis of an N-glycan isomer library. Chem Sci, 2015, 6, 5652-5661.

Lei Li*, Yonghui Liu, Tiehai Li, Wenjun Wang, Zaikuan Yu, Cheng Ma, Jingyao Qu, Wei Zhao, Xi Chen & Peng G. Wang*. Efficient chemoenzymatic synthesis of novel galacto-N-biose derivatives and their sialylated forms. Chem Commun, 2015, 51, 10310-10313.

2. Develop Glycomics Tools to Probe Glycans and Elucidate their Functions

Carbohydrates on glycoproteins and cell surfaces contain crucial biological information, which is decoded by glycan-binding proteins (GBPs). A major technical breakthrough in glycoscience to facilitate decode glycan functions and recognition was the development of glycan microarrays, in which picograms of defined glycans are immobilized on a solid surface and interrogated by a GBPs. We are developing such tools and applying them in screening cancer autoantibodies and elaborating the evolution and mutations of Influenza viruses (collaborated with Dr. Henry Wan at University of Missouri). We are also interested in developing mass-spectrometry based tools to profile and quantify glycans on proteins and cells, as well as probe specific glycoepitopes on cell surfaces. 

Related Publications

Cheng Ma, Ding Liu, Dong Li, Junping Zhang, Xiao-Qian Xu, He Zhu, Xiufeng Wan, Carol H. Miao, Barbara A. Konkle, Philip Onigman, Weidong Xiao* & Lei Li*. Comprehensive N- and O-glycosylation mapping of human coagulation factor V. J Thromb Haemost, 2020, doi: 10.1111/jth.14861.

He Zhu, Shuaishuai Wang, Ding Liu, Lang Ding, Congcong Chen, Yunpeng Liu Zhigang Wu, RoniBollag, Kebin Liu, Jun Yin, Cheng Ma, Lei Li* & Peng George Wang*. Identifying sialylation linkages at the glycopeptide level by glycosyltransferase labeling assisted mass spectrometry (GLAMS). Anal Chem, 2020, 92, 6297-6303.

Lei Li*, Wanyi Guan, Gaolan Zhang, Zhigang Wu, Hai Yu, Xi Chen & Peng George Wang. Microarray analyses of closely related glycoforms reveal different accessibilities of glycan determinants on N-glycan branches. Glycobiology, 2020, 30, 334-345.

Feng Wen, Lei Li, Meng-Jung Chiang, Nan Zhao, Hang Xie, Jim Cooley, Richard Webby, Peng G. Wang & Xiu-Feng Wan. A Y161F hemagglutinin substitution increases antigenic thermostability and improves yields of 2009 H1N1 influenza A virus in cells. J Virol, 2018, 92, e01621-17.

Related Funding:

U54HL142019 from NHLBI         (MPI: Xiao/Li/Miao)            06/2019 – 04/2023

Role: Principal Investigator of Project 2             

Title: Center for the Investigation of Factor VIII Inhibitors and Glycosylation

Goal: A major obstacle in treating hemophilia A is that ~25% of patients develop neutralizing anti-factor VIII (FVIII) antibodies (inhibitors) following protein replacement therapy. Using glycan microarray and other glycomics tools, we aims to define specific immunologic trigger by glycosylation and its associated mechanisms, leading to prevention or elimination of FVIII inhibitors.

3. Total Synthesis of Homogeneous Lipopolysaccharide against MDR pathogens 

Antibiotic resistance is one of the most serious health threats and a worldwide problem. Among the large and fast-growing numbers of antibiotic-resistant bacteria, gram-negative pathogens associated with nosocomial infections, e.g., multidrug-resistant (MDR) Pseudomonas aeruginosa, are of particular concern. Our interests are at developing lipopolysaccharide (LPS) based broad-spectrum vaccines and therapeutics against MDR P. aeruginosa. LPS (also known as endotoxin) is the major component of the outer membrane of gram-negative bacteria. Naturally separated LPS features heterogeneous due to incomplete modifications. We are using molecular biology and chemical biology tools to study the biosynthetic pathway, and applying organic/enzymatic approaches to produce homogeneous LPS and analogues.  

Related Publications

Lei Li, Robert L. Woodward, Weiqing Han, Jingyao Qu, Jing Song, Cheng Ma & Peng G. Wang. Chemoenzymatic synthesis of bacterial polysaccharide repeating unit-pyrophosphate-undecaprenyl and analogues. Nat Protoc, 2016, 11, 1280-1298.

Tiehai Li, Liuqing Wen, Adriel Williams, Baolin Wu, Lei Li, Jingyao Qu, Jeffrey Meisner, Zhongying Xiao, Junqing Fang & Peng G. Wang. Chemoenzymatic synthesis of ADP-D-glycero-b-D-manno-heptose and study of the substrate specificity of HldE.

Bioorg Med Chem, 2014, 22, 1139-1147.

Weiqing Han†, Baolin Wu†, Lei Li†, Guohui Zhao, Robert Woodward, Nicholas Pettit, Li Cai & Peng G. Wang. Defining the function of E. coli lipopolysaccharide O-antigen ligase WaaL using chemoenzymatically synthesized substrates. J Biol Chem, 2012, 287, 5357-5365.

Robert Woodward†, Wen Yi†, Lei Li†, Guohui Zhao†, Hironobu Eguchi†, Perali R. Sridhar, Hongjie Guo, Jing K. Song, Edwin Motari, Li Cai, Patrick Kelleher, Xianwei Liu, Weiqing Han, Wenpeng Zhang, Yan Ding, Mei Li & Peng G. Wang. In vitro bacterial polysaccharide biosynthesis: Defining the functions of Wzy and Wzz. Nat Chem Biol, 2010, 6, 418-423.

4. Carbohydrate-related Therapeutics against Clostridioides difficile Infections (CDI)

Designated as an “Urgent Threats Pathogen”, Clostridioides difficile is causing 453,000 infections and 29,000 deaths per year in USA. A major problem of CDI is high level of recurrences, 20–30% after first treatment, and up to 65% after the first recurrence. C. difficile is a gram-positive, spore-forming anaerobic bacterium that produces various types of glycan-related structures on the cell surface. Some glycans were proved to elicit specific immune responses. Our research interests are at the biosynthesis of C. difficile glycans and glycoconjugates. We are using molecular and synthetic techniques to elaborate the biosynthetic pathways, and targeting critical steps to develop inhibitors and mimics as novel vaccines and therapeutics against CDI. We are also interested in CDI glycan recognition, which includes a number of C. difficile proteins with adhesin properties. 

Related Publications

Zhongrui Ma, Gaolan Zhang, Madhusudhan Reddy Gadi, Yuxi Guo, Peng Wang & Lei Li*. Clostridioides difficile cd2775 encodes a unique mannosyl-1-phosphotransferase for polysaccharide II biosynthesis. ACS Infect Dis, 2020, 6, 680-686.

Related Funding:

U01GM125288 from NIGMS         (MPI: Yu/Kiessling/Li)        09//2017 – 07//2022
Role: Principal Investigator
Title: Chemoenzymatic synthesis of bacterial polysaccharides
Goal: Bacterial polysaccharides have broad applications in vaccine design, diagnosis, modulating the immune system, and probing carbohydrate-binding proteins. The project will develop effective chemoenzymatic approaches to access a diverse array of bacterial polysaccharides. 

® LI Glycoscience Group 2020

Address:   50 Decatur Street SE, Room 431

                 Atlanta, GA 30303