New access to complex glycoconjugates through engineering and evolution of glycosyltransferases and glycosynthases

報 告  人：Stephen G. Withers

加拿大不列顛哥倫比亞大學教授

英國皇家學會院士

加拿大皇家學會院士

UBC高通量生物學中心主任

報告時間🙅🏻‍♂️👩🏽‍💻：4月25號（星期五）上午 9:30

報告題目🌌：極端基因加工器：極端嗜熱微生物如何維持基因組穩定性

Extreme Gene Machines: how hyperthermophiles maintain genome integrity

報 告  人：馬爾科姆•懷特（Malcolm F White）

英國University of St Andrews教授

愛丁堡皇家學會院士

歐洲分子生物學組織 (EMBO)成員

國際期刊Biochemical Journal副主編

報告地點：閔行校區生物藥學樓樹華多功能廳

報告時間：4月25號（星期五）上午 10:30

聯 系  人：於晴   This e-mail address is being protected from spambots. You need JavaScript enabled to view it.

主講人簡介：

Stephen G. Withers教授是加拿大不列顛哥倫比亞大學Khorana講席教授、英國皇家學會院士🚰、加拿大皇家學會院士、加拿大化學會院士，現任加拿大化學生物首席研究科學家(Canada Research Chair)，UBC高通量生物學中心主任👩🏿‍🦳。他主要從事糖類代謝酶的作用機製、糖類合成酶分子改造、糖代謝酶小分子藥物設計研究🔛。他在糖化學生物領域有著卓越成就和重大影響。1992年獲加拿大皇家學會盧瑟福獎🙅🏿‍♂️👩‍👩‍👧‍👦，2002年獲國際碳水化合物組織惠斯勒獎，2012年獲英國皇家學會百年獎。

Malcolm F White是英國University of St Andrews教授、英國愛丁堡皇家科EON4院士📔、歐洲分子生物學組織 (EMBO)成員🧑🏼‍🎤。現任聖安德魯斯大學生物EON4科研院長，英國生物技術與生物科學研究理事會(BBSRC)委員🎨🧑🏽‍🌾，兼任生化領域著名國際期刊Biochemical Journal副主編🛫🎙。他綜合運用生物化學、分子生物學、蛋白質組學🎬、生物信息學等方法，研究核酸相關代謝機製👩🏻‍🚀，在古菌DNA損傷修復和基於CRISPR的抗病毒機製方面取得了令人矚目的研究成就，是活躍在微生物遺傳學研究前沿領域的著名學者👨‍✈️，在古菌遺傳學和結構生物學研究領域具有很大影響力。

報告摘要🦶🏻：

Glycans on the surfaces of cells play key roles in the interaction of that cell with its environment, primarily through interaction with specific protein-based receptors. Study of these interactions requires access to these complex glycans, while interference with these interactions, most likely through the use of competing glycans, is a possible therapeutic approach. Such studies require synthesis of glycans, and on a large scale in the case of therapeutics. Traditional routes to the enzymatic synthesis of oligosaccharides have either involved the use of Nature’s own biosynthetic enzymes, the glycosyl transferases, or glycosidases run in transglycosylation mode. Each approach has its drawbacks. Glycosynthases are mutant glycosidases in which the catalytic nucleophile has been removed. When used in conjunction with glycosyl fluorides of the opposite anomeric configuration to that of the substrate, these enzymes function as highly efficient transferases, frequently giving stoicheometric yields. Thioglycoligases are a new class of mutant glycosidases in which the acid/base catalyst has been mutated. These enzymes synthesise sulfur-linked oligosaccharides when an activated donor is used in conjunction with a thiosugar acceptor. Recent results in the engineering of these two classes of mutant enzymes, as well as of “classical” glycosyl transferases, will be discussed. Particular attention will be paid to their application to oligosaccharides and glycolipids. Emphasis will be placed upon the directed evolution of these enzymes using a variety of screening methodologies including robot-assisted ELISA assays and FACS cell sorting.

Archaea frequently inhabit extreme environments and thus face challenges in maintaining functional cellular structures and macromolecules, in particular DNA which must be repaired efficiently. The fundamental relationship between the archaea and eukarya means that studies of the former can shed light on processes and proteins essential for human health. This talk will focus on recent research in our laboratory on the Nucleotide Excision Repair (NER) pathway in the model crenarchaeon Sulfolobus solfataricus, which grows in volcanic pools at 80°C. NER removes bulky lesions such as photoproducts from DNA. Lesions are detected, DNA unwound locally and nicks introduced on either side of the damage to release an oligonucleotide “patch” containing the damage. The gapped product is then repaired by DNA synthesis. The enzymatic components of eukaryal NER are the XPB and XPD helicases (components of transcription factor TFIIH) and the XPF and XPG nucleases. By studying these enzymes in archaea we can gain important insights into human health and disease. A second challenge facing most living things is the threat posed by viruses and other mobile genetic elements. The recently discovered CRISPR system is a prokaryotic adaptive immune system that provides RNA-mediated defence against invading nucleic acid entities. Recent work in our laboratory on the Type III Interference machines of the CRISPR system will be described.