Synthesis and function of novel bacterial carbohydrates

新型细菌碳水化合物的合成与功能

• 批准号: RGPIN-2016-04765
• 负责人: Creuzenet, Carole
• 金额: $ 2.4万
• 依托单位: University of Western Ontario
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=615289
• 关键词: Synthesis; function; novel; bacterial; carbohydrates

The glycome represents an extra layer of information above the genome, transcriptome and proteome and deciphering its role is a fundamental question. This question is particularly important in bacteria that produce a wide variety of glycans of heterogeneous composition. Elucidating their biosynthesis will allow assessing their function and harnessing the potential of novel sugar synthesis enzymes for biotechnology applications. We focused on modified heptoses from Campylobacters or Yersiniae and characterized 9 heptose modification enzymes that affect the function of the capsule and lipopolysaccharide in which the modified heptoses reside. Our work showed that heptose modifying reductases and epimerases from C. jejuni have very precise substrate and product specificities. The current proposal focuses on understanding the molecular basis of such specificity, and on elucidating the function of new methyltransferases and oxidases in heptose modification. Our work also highlighted a novel putative regulator within the C. jejuni capsular cluster, and also suggests co-regulation of capsule synthesis with the synthesis of other glycans. Elucidating the mechanisms involved may allow to better delineate the physiological role of each pathway and understand how they are integrated under physiological conditions. We hypothesize that: (i) the reductases and epimerases involved in heptose modification have unique substrate / product specificities that can be exploited for biotechnological applications; (ii) novel putative methyl-transferases and a dedicated oxidase are involved in heptose modification and (iii) a novel regulator regulates heptose modification, capsule synthesis, and other surface carbohydrates. Our specific objectives are to: 1/ investigate the molecular basis for substrate / product specificities of heptose modifying epimerases and reductases. 2/ determine the role of putative methyltransferases, oxidase and regulator on heptose modification and production of capsule and other surface carbohydrates. The proposed research is of general significance as modified heptoses and other unusual sugars are found in surface carbohydrates of numerous bacteria. The information derived from our structure / function studies on determinants for substrate and product specificities will facilitate the elucidation of the synthesis pathways for other bacterial sugars. This research will also delineate regulatory mechanism involved in sugar synthesis to better understand the interplay between sugar synthesis pathways and their effect on bacterial physiology. Finally, this research will provide substrates enabling the studies of glycosyltransferases involved in the assembly of complex carbohydrate structures. This could lead to technological applications of heptose modifying enzymes for the production of complex carbohydrates.

糖代表了基因组、转录组和蛋白质组之上的额外信息层，破译它的作用是一个基本问题。这个问题在产生多种异质组成的聚糖的细菌中尤为重要。阐明它们的生物合成将有助于评估它们的功能，并利用新型糖合成酶在生物技术应用中的潜力。我们重点研究了弯曲杆菌和耶尔森菌的修饰的庚糖，并鉴定了9种影响修饰的庚糖所处的胶囊和脂多糖功能的庚糖修饰酶。我们的研究表明，空肠梭菌的庚糖修饰还原酶和外链酶具有非常精确的底物和产物特异性。