Understanding and exploiting the Mce proteins from Streptomyces

链霉菌是一种无害的土壤细菌，经常在植物根部周围发现，与植物相互作用，但不会引起疾病。链霉菌还与其他土壤生物相互作用，如阿米巴变形虫，这是一种单细胞生物，其行为类似于人体的吞噬细胞，以细菌细胞为食。最近，我们能够在链霉菌中发现一组基因（mce基因，代表哺乳动物细胞进入基因），它们与链霉菌的远亲结核分枝杆菌的基因非常密切相关，结核分枝杆菌是导致结核病的细菌。我们发现链霉菌中的这些mce基因编码ABC转运体和六种底物结合蛋白的成分，这些成分对从环境中收集营养物质很重要。然而，在结核分枝杆菌中，它们需要在人类肺细胞中定植并在这些细胞中生长。这项学生提案旨在更详细地研究这种mce转运体系统，以便在（生物）化学工业中加以利用。我们将在蛋白质水平上充分表征这种转运系统，并研究它们结合和吸收底物的分子细节，以及这如何有助于它们的生物学作用。这项研究的发现将对我们理解人类和动物病原体如何从非致病性细菌进化而来，以及我们如何利用这些蛋白质作为病原体的潜在新药和疫苗靶点产生影响。最近已经发现这些Mce蛋白的同源物存在于革兰氏阴性细菌中，并且令人兴奋地对生长和生存至关重要。这开启了一种可能性，即更深入地了解它们的功能，可以帮助开发针对各种细菌病原体的药物，这些细菌病原体目前由于抗微生物药物耐药性菌株的增加而引起关注。这种蛋白质家族非常多样化，它们也有可能用于生物技术/生物催化行业，通过增加疏水底物（如甾醇）的运输，帮助从植物废物中制造有用的药物，例如类固醇，然后在细菌细胞内进行生物转化。这突出了这一蛋白质家族的重要性，他们的研究对人类健康和工业生物技术具有重要意义。这项学生提案有四个主要目标，与我们理解和利用链霉菌的mce基因的总体目标有关：1)确定链霉菌mce位点的功能冗余水平——即，为什么mce底物蛋白有多个拷贝，这是否反映了底物结合能力和代谢多功能性的增强？2)利用RNASeq全面表征链霉菌mce蛋白的调控。3)通过Mce转运体了解底物的转运机制4)开发Mce蛋白在生物催化和生物转化中的应用

Streptomyces is a harmless soil bacterium that is often found around the roots of plants, interacting with them but without causing disease. Streptomyces also interacts with other soil organisms such as amoeba, single celled organisms that behave like the phagocytic cells in the human body, eating bacterial cells. Recently we were able to identify that a group of genes (the mce genes, which stands for Mammalian Cell Entry genes) that are found in Streptomyces and are very closely related to genes in its distant cousin Mycobacterium tuberculosis, the bacterium that causes TB. We showed that these mce genes in Streptomyces encode the components of an ABC transporter and six substrate binding proteins that are important for gathering nutrients from the environment. Yet in M. tuberculosis they are required for them to colonise human lung cells and grow within those cells. This studentship proposal is aimed at more detailed study of this mce transporter system so it can be exploited in the (bio)chemical industry. We will fully characterise this transport system at the protein level and study the molecular details of what substrates they bind and take up, and how this contributes to their biological role. The findings of this study will have implications for our understanding of how human and animal pathogens have evolved from non-pathogenic bacteria and how we can exploit these proteins as potential novel drug and vaccine targets for pathogens. Recently it has been found that homologues of these Mce proteins are present in Gram-negative bacteria and excitingly are essential for growth and survival. This opens up the possibility that a deeper understanding of their function can help develop drugs against a whole range of bacterial pathogens which are currently causing concern due to the rise of antimicrobial resistant strains. This protein family is very diverse and there are also possibilities that they can be used in the biotechnology/biocatalysis industry to help make useful drugs, such as steroids from plant waste products by increasing the transport of hydrophobic substrates such as sterols that can then be biotransformed within bacterial cells. This highlights the importance of this protein family and that their study has implications for human health and industrial biotechnology. This studentship proposal has four main objectives that are linked to our overall aim of understanding and exploiting the mce genes from Streptomyces 1) To determine the level of functional redundancy in the Streptomyces mce locus - i.e. why are there multiple copies of Mce substrate proteins and does this reflect increased substrate binding capability and metabolic versatility?2) To fully characterise the regulation of mce proteins from Streptomyces using RNASeq.3) To understand the transport mechanism of substrates via the Mce transporter4) To develop the use of Mce proteins for biocataysis and biotransformation