Mechanistic Studies on the Remarkable Epimerisations of Clavam and Carbapenem Biosynthesis

克拉酰胺和碳青霉烯生物合成显着差向异构化的机理研究

• 批准号: BB/F006349/1
• 负责人: Christopher Joseph Schofield
• 金额: $ 78.79万
• 依托单位: University of Oxford
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2008
• 资助国家: 英国
• 起止时间: 2008 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FF006349%2F1
• 关键词: Mechanistic; Studies; Remarkable; Epimerisations; Clavam

Despite problems of resistance, antibiotics are arguably the most important molecules used in medicine. Worldwide the most important antibiotics, by commercial or medicinal standards, are the penicillins and related structures all of which contain a four membered beta-lactam ring. The beta-lactam characterises not only the penicillins but also other important antibiotics such as the cephalosporins. This ring is vital for antibacterial activity since it reacts with the enzymes located in the bacterial cell wall that are the targets of these antibiotics. When the antibiotics neutralise their target enzymes the bacteria cannot properly synthesise their cell walls and so cannot survive. As Fleming observed, despite the observations that penicillins are lethal to many bacteria, beta-lactams are actually produced by microorganisms. In fact the structures of the naturally occurring bicyclic beta-lactam antibiotics are so complex and unusual that it is highly improbable they would be discovered by human synthesis either by design or chance. With few exceptions all the beta-lactams in use are produced either by direct fermentation of microorganisms or by synthetic modification of fermented materials, as their total synthesis from petrochemicals is too expensive. As with all antibiotic families the continued use of beta-lactams is threatened by resistance. This can take various forms including camouflage of the target and the evolution of molecular pumps to expel the antibiotics. One important resistance mechanism involves enzymes that break the beta-lactam ring by addition of water. These beta-lactamases have evolved to be highly efficient as their activity can be a matter of life or death for bacteria. To counter the activity of beta-lactamases humans have developed new families of antibiotics that are less susceptible to beta-lactamase mediated hydrolysis or actually inhibit beta-lactmase activity. Such families include the cephalosporins and the carbapenems. Remarkably the clinically useful inhibitors have themselves all turned out to be beta-lactams. Some of these compounds were very potent beta-lactamase inhibitors but were not powerful enough antibiotics for sole use, so are formulated with a penicillin antibiotic. There is an ongoing need for new antibiotics and beta-lactamase inhibitors as bacteria continually evolve better methods of resistance. A limitation in this development is the production costs of useful compounds. In the case of the carbapenems this problem is particularly acute as no method for their commercially viable fermentation has been developed, so they are prepared by expensive total synthesis. We have been studying the routes by which microorganisms make beta-lactams. Our work together with that of others has revealed that bicyclic beta-lactams are produced by the action of chemically remarkable enzymes. The enzymes that catalyse the biosynthesis of the two rings of the four most important groups of beta-lactams, the penicillins, the cephalosporins, the clavams and the carbapenems, have been identified. In order to bind the antibiotics to their molecular targets these rings have to be both modified or functionalised with other chemical groups and their three dimensional shape (stereochemistry) has to be changed. In the new work we aim to attempt to understand how these unusual reactions, most of which are poorly understood, occur. The work is of practical significance in terms of developing new or more efficient routes to antibiotics; because the enzymes involved catalyse highly unusual reactions we envisage that the work will have unenvisaged applications. This was the case in work on the enzymes involved in the production of the beta-lactam rings which has turned out to have widespread implications for work on the mechanism by which animal cells respond to low oxygen concentrations and has applications in cancer and heart disease.

尽管存在耐药性问题，但抗生素可以说是医学中最重要的分子。在世界范围内，按照商业或医药标准，最重要的抗生素是青霉素和相关结构，它们都含有四元β-内酰胺环。β-内酰胺不仅是青霉素的特征，也是其他重要抗生素如头孢菌素的特征。这个环对于抗菌活性至关重要，因为它与位于细菌细胞壁中的酶反应，这些酶是这些抗生素的目标。当抗生素中和它们的目标酶时，细菌不能正确地合成它们的细胞壁，因此不能存活。正如弗莱明所观察到的，尽管青霉素对许多细菌是致命的，但β-内酰胺实际上是由微生物产生的。事实上，天然存在的双环β-内酰胺抗生素的结构是如此复杂和不寻常，以至于它们极不可能通过人类合成而被发现，无论是设计还是偶然。除了少数例外，所有使用中的β-内酰胺都是通过微生物的直接发酵或通过发酵材料的合成改性来生产的，因为它们从石油化学品的总合成太昂贵了。与所有抗生素家族一样，β-内酰胺类抗生素的持续使用受到耐药性的威胁。这可以采取各种形式，包括伪装目标和分子泵的进化以排出抗生素。一种重要的耐药机制涉及通过加入水来破坏β-内酰胺环的酶。这些β-内酰胺酶已经进化成高效的，因为它们的活性可能是细菌的生死问题。为了对抗β-内酰胺酶的活性，人类已经开发出对β-内酰胺酶介导的水解不太敏感或实际上抑制β-内酰胺酶活性的新抗生素家族。此类家族包括头孢菌素类和碳青霉烯类。值得注意的是，临床上有用的抑制剂本身都是β-内酰胺。这些化合物中的一些是非常有效的β-内酰胺酶抑制剂，但对于单独使用来说不够强大的抗生素，因此与青霉素抗生素一起配制。随着细菌不断进化出更好的耐药性方法，对新的抗生素和β-内酰胺酶抑制剂的需求不断增加。这种发展的一个限制是有用化合物的生产成本。在碳青霉烯类的情况下，这个问题特别严重，因为还没有开发出商业上可行的发酵方法，所以它们是通过昂贵的全合成制备的。我们一直在研究微生物制造β-内酰胺的途径。我们和其他人的工作表明，双环β-内酰胺是通过化学上显著的酶的作用产生的。已经鉴定了催化四种最重要的β-内酰胺类（青霉素类、头孢菌素类、克拉维类和碳青霉烯类）的两个环的生物合成的酶。为了将抗生素结合到它们的分子靶标上，这些环必须用其他化学基团修饰或官能化，并且它们的三维形状（立体化学）必须改变。在这项新工作中，我们的目标是试图了解这些不寻常的反应是如何发生的，其中大多数都知之甚少。这项工作在开发新的或更有效的抗生素途径方面具有实际意义;因为所涉及的酶催化非常不寻常的反应，我们设想这项工作将有意想不到的应用。这是在参与生产β-内酰胺环的酶的工作中的情况，这已经被证明对动物细胞对低氧浓度的反应机制的工作具有广泛的影响，并在癌症和心脏病中有应用。

项目成果

Stereoselective preparation of lipidated carboxymethyl-proline/pipecolic acid derivatives via coupling of engineered crotonases with an alkylmalonyl-CoA synthetase.

通过工程化巴豆酸酶与烷基丙二酸单酰辅酶A合成酶的偶联，立体选择性地制备脂质化羧甲基脯氨酸/哌可酸衍生物。

• DOI: 10.1039/c3ob41525b
• 发表时间: 2013
• 期刊: Organic & biomolecular chemistry
• 影响因子: 3.2
• 作者: Hamed RB

Stereoselective C-C bond formation catalysed by engineered carboxymethylproline synthases.

工程化羧甲基脯氨酸合酶催化立体选择性 C-C 键形成。

• DOI: 10.1038/nchem.1011
• 发表时间: 2011
• 期刊: Nature chemistry
• 影响因子: 21.8
• 作者: Hamed RB

Methyl 6-amino-6-oxohexa-noate.

• DOI: 10.1107/s1600536812003303
• 发表时间: 2012-03-01
• 期刊: Acta crystallographica. Section E, Structure reports online
• 作者: Gruber T;Schofield CJ;Thompson AL
• 通讯作者: Thompson AL

Stereoselective Production of Dimethyl-Substituted Carbapenams via Engineered Carbapenem Biosynthesis Enzymes

通过工程碳青霉烯生物合成酶立体选择性生产二甲基取代的碳青霉烯类

• DOI: 10.1021/acscatal.6b02509
• 发表时间: 2017
• 期刊: ACS Catalysis
• 影响因子: 12.9
• 作者: Hamed R

3-Meth-oxy-3-oxopropanaminium chloride.

• DOI: 10.1107/s1600536812003297
• 发表时间: 2012-03-01
• 期刊: Acta crystallographica. Section E, Structure reports online
• 作者: Gruber T;Schofield CJ;Thompson AL
• 通讯作者: Thompson AL