Chemoenzymatic modular assembly of O-GalNAc glycans for functional glycomics

Shuaishuai Wang,Fengshan Wang,Ding Liu,Kebin Liu,Wanyi Guan,Congcong Chen,Lei Li,Varma Saikam,He Zhu,Madhusudhan Reddy Gadi,Roni Bollag,Xi Chen,Peng George Wang,Peixue Ling

doi:10.1038/s41467-021-23428-x

Abstract

O-GalNAc glycans (or mucin O-glycans) play pivotal roles in diverse biological and pathological processes, including tumor growth and progression. Structurally defined O-GalNAc glycans are essential for functional studies but synthetic challenges and their inherent structural diversity and complexity have limited access to these compounds. Herein, we report an efficient and robust chemoenzymatic modular assembly (CEMA) strategy to construct structurally diverse O-GalNAc glycans. The key to this strategy is the convergent assembly of O-GalNAc cores 1–4 and 6 from three chemical building blocks, followed by enzymatic diversification of the cores by 13 well-tailored enzyme modules. A total of 83 O-GalNAc glycans presenting various natural glycan epitopes are obtained and used to generate a unique synthetic mucin O-glycan microarray. Binding specificities of glycan-binding proteins (GBPs) including plant lectins and selected anti-glycan antibodies towards these O-GalNAc glycans are revealed by this microarray, promoting their applicability in functional O-glycomics. Serum samples from colorectal cancer patients and healthy controls are assayed using the array reveal higher bindings towards less common cores 3, 4, and 6 than abundant cores 1 and 2, providing insights into O-GalNAc glycan structure-activity relationships.

Highlights

O-GalNAc glycans play pivotal roles in diverse biological and pathological processes, including tumor growth and progression
Pathogens could harness cell surface glycans as entry receptors to initiate infection[5], or produce surface glycans mimicking host O-GalNAc glycans to escape from the host immune surveillance[6]
The chemoenzymatic modular assembly (CEMA) strategy includes (1) diversity-oriented and scalable chemical assembly of O-GalNAc glycan cores, and (2) highly efficient enzyme modules to glycosylate the cores with precise control on regio- and stereoselectivity

Summary

Introduction

O-GalNAc glycans (or mucin O-glycans) play pivotal roles in diverse biological and pathological processes, including tumor growth and progression. The CEMA strategy includes (1) diversity-oriented and scalable chemical assembly of O-GalNAc glycan cores, and (2) highly efficient enzyme modules to glycosylate the cores with precise control on regio- and stereoselectivity.

Results

Conclusion