Structural studies of Lactococcus lactis bacteriophage proteins

乳酸乳球菌噬菌体蛋白的结构研究

• 批准号: RGPIN-2017-06482
• 负责人: Gagné, Stéphane
• 金额: $ 1.89万
• 依托单位: Université Laval
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=651339
• 关键词: Structural; studies; Lactococcus; lactis; bacteriophage

The Canadian dairy industry heavily relies on the bacterial fermentation for the transformation of milk into products such as cheese and yogurt. An average cheese plant transforms ~1,000,000 litres of milk per day. The starter cultures are a combination of lactic acid bacteria, and Lactococcus lactis is the most important species for cheese manufacture. A cheese plant will rotate different starter cultures, requiring numerous bacterial strains that are carefully selected based on microbiological, biochemical, and technical properties.******In the nonsterile environment of pasteurized milk, the added and preferred bacterial cells will come into contact with ubiquitous virulent phages found in milk. Phages (or bacteriophages) are viruses that infect and replicate within a bacterium. Phage concentration is usually low in milk, but phage population can increase rapidly during the 34 hours cheese making process; virulent lactococcal phages have a 30 min cycle and release of 50-100 virions per infected cell. For decades, the dairy industry has relied on an array of control measures. In spite of these efforts, phages are evolving and variants keep emerging, and phage attacks remain today the most common cause of manufacturing problems in the cheese industry. An in depth understanding of phages will, without a doubt, lead to better strategies for the long-term and optimize control of these phages.******Our primary goal is to significantly increase our knowledge of L. lactis phages that affect the Canadian dairy industry through a characterization of all proteins encoded by these viruses. Even though phages are the most abundant biological entities on the planet (~1032 phages in the biosphere resulting in ~1023 infections per second), about 75% of phage genes have unknown functions. Lactococcal phages are classified into ten distinct groups. The 936-type represent 90% of lactococcal phages found in dairy manufacturing facilities and they are the most troublesome. To date, 56 complete genomes of 936-type phages are available. These dsDNA phages encode for few proteins, most of which have unknown functions.******Using a distinct and global approach, we propose to tackle all 3000+ proteins from all 936-type phages with available genome sequences. Structures are essential to understand protein function. In addition, local dynamics in proteins are omnipresent. These movements directly influence events such as ligand binding and catalysis; hence the study of protein dynamics is also essential to understand function. Hence, we also propose in-depth studies of structure and dynamics of highly conserved proteins selected among the 936-type phages. In the first 5 years of this project, we will combine modern prediction tools, solution NMR and molecular dynamics simulations to gather structural and dynamics data on 936-type phage proteins.

加拿大乳制品行业严重依赖细菌发酵将牛奶转化为奶酪和酸奶等产品。一个普通的奶酪工厂每天转化约100万升牛奶。发酵剂是乳酸菌的组合，乳酸乳球菌是奶酪制造中最重要的菌种。奶酪工厂将旋转不同的发酵剂，需要根据微生物，生物化学和技术特性精心选择的许多细菌菌株。在巴氏消毒奶的非无菌环境中，添加的和优选的细菌细胞将与牛奶中普遍存在的有毒细菌接触。噬菌体（或噬菌体）是感染细菌并在细菌内复制的病毒。乳中噬菌体浓度通常较低，但在34小时的奶酪制作过程中，噬菌体数量会迅速增加;毒性乳球菌的周期为30分钟，每个感染细胞释放50-100个病毒粒子。几十年来，乳制品行业一直依赖于一系列控制措施。尽管做出了这些努力，但噬菌体仍在进化，变种不断出现，噬菌体攻击仍然是奶酪行业制造问题的最常见原因。毫无疑问，深入了解这些风险将有助于制定更好的长期战略，并优化对这些风险的控制。我们的主要目标是大大增加我们对L的了解。通过对这些病毒编码的所有蛋白质的表征，对影响加拿大乳制品行业的乳酸链球菌进行了研究。尽管噬菌体是地球上最丰富的生物实体（生物圈中约1032个噬菌体导致每秒约1023次感染），但约75%的噬菌体基因具有未知的功能。乳球菌属分为十个不同的组。936型代表了乳制品生产设施中发现的90%的乳球菌，它们是最麻烦的。到目前为止，已经有56个936型猪的完整基因组。这些双链DNA双链DNA编码的蛋白质很少，其中大部分功能未知。使用一种独特的全球方法，我们建议用可用的基因组序列来处理来自所有936型大肠杆菌的所有3000多种蛋白质。结构对于理解蛋白质功能至关重要。此外，蛋白质中的局部动力学无处不在。这些运动直接影响配体结合和催化等事件;因此蛋白质动力学的研究对于理解功能也至关重要。因此，我们还建议深入研究936-型突变体中高度保守的蛋白质的结构和动力学。在这个项目的前5年，我们将结合联合收割机现代预测工具，溶液NMR和分子动力学模拟，收集936型噬菌体蛋白的结构和动力学数据。