Combinatorial biosynthesis of 5-O-desosaminyl erythronolide A as a potent precursor of ketolide antibiotics

A Review of the Microbial Production of Bioactive Natural Products and Biologics

A variety of organisms, such as bacteria, fungi, and plants, produce secondary metabolites, also known as natural products. Natural products have been a prolific source and an inspiration for numerous medical agents with widely divergent chemical structures and biological activities, including antimicrobial, immunosuppressive, anticancer, and anti-inflammatory activities, many of which have been developed as treatments and have potential therapeutic applications for human diseases. Aside from natural products, the recent development of recombinant DNA technology has sparked the development of a wide array of biopharmaceutical products, such as recombinant proteins, offering significant advances in treating a broad spectrum of medical illnesses and conditions. Herein, we will introduce the structures and diverse biological activities of natural products and recombinant proteins that have been exploited as valuable molecules in medicine, agriculture and insect control. In addition, we will explore past and ongoing efforts along with achievements in the development of robust and promising microorganisms as cell factories to produce biologically active molecules. Furthermore, we will review multi-disciplinary and comprehensive engineering approaches directed at improving yields of microbial production of natural products and proteins and generating novel molecules. Throughout this article, we will suggest ways in which microbial-derived biologically active molecular entities and their analogs could continue to inspire the development of new therapeutic agents in academia and industry.

Cytochromes P450 for natural product biosynthesis in Streptomyces: sequence, structure, and function

Covering: up to January 2017Cytochrome P450 enzymes (P450s) are some of the most exquisite and versatile biocatalysts found in nature. In addition to their well-known roles in steroid biosynthesis and drug metabolism in humans, P450s are key players in natural product biosynthetic pathways. Natural products, the most chemically and structurally diverse small molecules known, require an extensive collection of P450s to accept and functionalize their unique scaffolds. In this review, we survey the current catalytic landscape of P450s within the Streptomyces genus, one of the most prolific producers of natural products, and comprehensively summarize the functionally characterized P450s from Streptomyces. A sequence similarity network of >8500 P450s revealed insights into the sequence-function relationships of these oxygen-dependent metalloenzymes. Although only ∼2.4% and <0.4% of streptomycete P450s have been functionally and structurally characterized, respectively, the study of streptomycete P450s involved in the biosynthesis of natural products has revealed their diverse roles in nature, expanded their catalytic repertoire, created structural and mechanistic paradigms, and exposed their potential for biomedical and biotechnological applications. Continued study of these remarkable enzymes will undoubtedly expose their true complement of chemical and biological capabilities.

A new mycinosyl rosamicin derivative produced by an engineered Micromonospora rosaria mutant with a cytochrome P450 gene disruption introducing the D-mycinose biosynthetic gene

Genetic engineering of post-polyketide synthase-tailoring genes can be used to generate new macrolide analogs through manipulation of the genes involved in their biosynthesis. Rosamicin, a 16-member macrolide antibiotic produced by Micromonospora rosaria IFO13697, contains a formyl group and an epoxide at C-20 and C-12/13 positions which are formed by the cytochrome P450 enzymes RosC and RosD, respectively. The D-mycinose biosynthesis genes in mycinamicin II biosynthesis gene cluster of Micomonospora guriseorubida A11725 were introduced into the rosC and rosD disruption mutants of M. rosaria IFO13697. The resulting engineered strains, M. rosaria TPMA0054 and TPMA0069, produced mycinosyl rosamicin derivatives, IZIV and IZV, respectively. IZIV was identified as a novel mycinosyl rosamicin derivative, 23-O-mycinosyl-20-deoxo-20-dihydrorosamicin.

Follow-up of natural products isolation

Follow-up of natural products isolation refers to re-isolation of compound(s) of interest in larger amounts for further pharmacological testing, conclusive structure elucidation, structure modifications to synthesize analogs for structure-activity relationships (SAR) studies, preformulation and formulation studies or clinical trials. In addition to conventional synthetic chemistry approaches, several other methodologies can be applied for following-up natural products isolation. This chapter outlines, with specific examples, various strategies and methods involved in follow-up of natural products isolation.

New macrolide, lincosaminide and streptogramin B antibiotics

IMPORTANCE OF THE FIELD

New antibiotics are needed to overcome microbial resistance and to improve on the therapeutic index and clinical effectiveness of existing agents.

AREA COVERED IN THIS REVIEW

This review covers the journal and patent literature published from about the mid-2000s to 2010 to provide an overview of the large diversity of new chemical entities in the macrolide, lincosaminide and streptogramin B (MLS(B)) class.

WHAT THE READER WILL GAIN

The review identifies areas of the greatest effort and recent results in pursuing structure-activity relationships among MLS(B) antibiotics and highlights preclinical and clinical candidates that have arisen from these diverse discovery programs.

TAKE HOME MESSAGE

Research on the MLS(B) class appears promising for the eventual registration and commercialization of several new antibiotics that improve the clinical effectiveness of existing agents and combat antibiotic-resistant pathogens.

Genetic engineering of macrolide biosynthesis: past advances, current state, and future prospects

Polyketides comprise one of the major families of natural products. They are found in a wide variety of bacteria, fungi, and plants and include a large number of medically important compounds. Polyketides are biosynthesized by polyketide synthases (PKSs). One of the major groups of polyketides are the macrolides, the activities of which are derived from the presence of a macrolactone ring to which one or more 6-deoxysugars are attached. The core macrocyclic ring is biosynthesized from acyl-CoA precursors by PKS. Genetic manipulation of PKS-encoding genes can result in predictable changes in the structure of the macrolactone component, many of which are not easily achieved through standard chemical derivatization or total synthesis. Furthermore, many of the changes, including post-PKS modifications such as glycosylation and oxidation, can be combined for further structural diversification. This review highlights the current state of novel macrolide production with a focus on the genetic engineering of PKS and post-PKS tailoring genes. Such engineering of the metabolic pathways for macrolide biosynthesis provides attractive alternatives for the production of diverse non-natural compounds. Other issues of importance, including the engineering of precursor pathways and heterologous expression of macrolide biosynthetic genes, are also considered.