Category Archives: Publications

Filipins: the first antifungal “weed killers” identified from bacteria isolated from the trap-ant

Allomerus ants ensure that they have sufficient nitrogen in their diet by trapping and consuming other insects. In order to construct their traps, like the more extensively studied leaf cutter ants, they employ fungal farming. Pest management within these fungal cultures has been speculated to be due to the ants’ usage of actinomycetes capable of producing antifungal compounds, analogous to the leafcutter ant mutualism. Here we report the first identification of a series of antifungal compounds, the filipins, and their associated biosynthetic genes isolated from a bacterium associated with this system.

Gao H, Grüschow S, Barke J, Seipke RF, Hill LM, Orivel K, Yu DW, Hutchings M, Goss RJM

RSC Adv. 2014, 4, 57267

Mechanism of action of the uridyl peptide antibiotics: an unexpected link to a protein–protein interaction site in translocase MraY

The pacidamycin and muraymycin uridyl peptide antibiotics show some structural resemblance to an Arg-Trp-x-x-Trp sequence motif for protein–protein interaction between bacteriophage [curly or open phi]X174 protein E and E. coli translocase MraY. Members of the UPA class, and a synthetic uridine–peptide analogue, were found to show reduced levels of inhibition to F288L or E287A mutant MraY enzymes, implying that the UPAs interact at this extracellular site as part of the enzyme inhibition mechanism.

Rodolis MT, Mihalyi A, Ducho C, Eitel K, Gust B, Goss RJM, Bugg TDH

Chem. Commun. 2014, 50, 13023

Access to High Value Natural and Unnatural Products through Hyphenating Chemical Synthesis and Biosynthesis

Access to natural products and their analogues is crucial. Such compounds have, for many years, played a central role in the area of drug discovery as well as in providing tools for chemical biology­. The ability to quickly and inexpensively acquire genome sequences has accelerated the field of natural product research. Access to genomic data coupled with new technologies for the engineering of organisms is resulting in the identification of large numbers of previously undiscovered natural products as well as an increased understanding of how the biosynthetic pathways responsible for the biogenesis of these compounds may be manipulated. This short review summarizes and reflects upon approaches to accessing natural products and has a particular focus on approaches combining molecular biology and synthetic chemistry.

Mahoney KPP, Smith DRM, Bogosyan EJA, Goss RJM

Synthesis 2014, 46 (16), 2122

The First One-Pot Synthesis of l-7-Iodotryptophan from 7-Iodoindole and Serine, and an Improved Synthesis of Other l-7-Halotryptophans

A simple and scalable one-pot biotransformation enables direct access to l-halotryptophans, including l-7-iodotryptophan, from the corresponding haloindoles. The biotransformation utilizes an easy to prepare bacterial cell lysate that may be stored as the lyophilizate for several months and utilized as a catalyst as and when required.

Smith, DRM, Willemse T, Gkotsi DS, Schepens W, Maes BU, Ballet S, Goss RJM

Org Lett 2014, 16 (10) 2622-2625

Natural Products: Discourse, Diversity, and Design

Natural Products: Discourse, Diversity and Design provides an informative and accessible overview of discoveries in the area of natural products in the genomic era, bringing together advances across the kingdoms.  As genomics data makes it increasingly clear that the genomes of microbes and plants contain far more genes for natural product synthesis than had been predicted from the numbers of previously identified metabolites, the potential of these organisms to synthesize diverse natural products is likely to be far greater than previously envisaged.  Natural Products addresses not only the philosophical questions of the natural role of these metabolites, but also the evolution of single and multiple pathways, and how these pathways and products may be harnessed to aid discovery of new bioactives and modes of action.

Edited by recognized leaders in the fields of plant and microbial biology, bioorganic chemistry and natural products chemistry, and with contributions from researchers at top labs around the world, Natural Products is unprecedented in its combination of disciplines and the breadth of its coverage. Natural Produces: Discourse, Diversity and Design  will appeal to advanced students and experienced researchers, from academia to industry, in diverse areas including ecology, industrial biotechnology, drug discovery, medicinal chemistry, agronomy, crop improvement, and natural product chemistry.

Osbourn A (ed), Goss R (ed), Carter GT (ed)

April 2014, Wiley-Blackwell. ISBN: 978-1-118-29806-0

Optimisation of engineered Escherichia coli biofilms for enzymatic biosynthesis of l-halotryptophans

Engineered biofilms comprising a single recombinant species have demonstrated remarkable activity as novel biocatalysts for a range of applications. In this work, we focused on the biotransformation of 5-haloindole into 5-halotryptophan, a pharmaceutical intermediate, using Escherichia coli expressing a recombinant tryptophan synthase enzyme encoded by plasmid pSTB7. To optimise the reaction we compared two E. coli K-12 strains (MC4100 and MG1655) and their ompR234 mutants, which overproduce the adhesin curli (PHL644 and PHL628). The ompR234 mutation increased the quantity of biofilm in both MG1655 and MC4100 backgrounds. In all cases, no conversion of 5-haloindoles was observed using cells without the pSTB7 plasmid. Engineered biofilms of strains PHL628 pSTB7 and PHL644 pSTB7 generated more 5-halotryptophan than their corresponding planktonic cells. Flow cytometry revealed that the vast majority of cells were alive after 24 hour biotransformation reactions, both in planktonic and biofilm forms, suggesting that cell viability was not a major factor in the greater performance of biofilm reactions. Monitoring 5-haloindole depletion, 5-halotryptophan synthesis and the percentage conversion of the biotransformation reaction suggested that there were inherent differences between strains MG1655 and MC4100, and between planktonic and biofilm cells, in terms of tryptophan and indole metabolism and transport. The study has reinforced the need to thoroughly investigate bacterial physiology and make informed strain selections when developing biotransformation reactions.

Perni S, Hackett L, Goss RJM, Simmons MJ, Overton TW

AMB Express 2013, 3:66 

Scope and potential of halogenases in biosynthetic applications

Smith DRM; Grüschow S; Goss RJM

Curr Opin Chem Biol 2012, 17 (2) 276-283

A large and diverse series of halogenated natural products exist. In many of these compounds the halogen is important to biological activity and bioavailability. We now recognise that nature has developed many different halogenation strategies for which well-known enzyme classes such as haem oxidases or flavin-dependent oxidases have been adapted. Enzymes capable of halogenating all kinds of different chemical groups from electron-rich to electron-poor, from aromatic to aliphatic have been characterised. Given that synthetic halogenation reactions are not trivial transformations and that halogenated molecules possess pharmaceutical usefulness, it will be worth investing into further research of halogenating enzymes.

Glycosyltransferases from Oat (Avena) Implicated in the Acylation of Avenacins

Amorn Owatworakit ; Belinda Townsend ; Thomas Louveau ; Helen Jenner ; Martin Rejzek ; Richard K. Hughes ; Gerhard Saalbach ; Xiaoquan Qi ; Saleha Bakht ; Abhijeet Deb Roy ; Sam T. Mugford ; Rebecca J. M. Goss ; Robert A. Field ; Anne Osbourn

J Biol Chem 2013, 288 (6) 3696-3704

Plants produce a huge array of specialized metabolites that have important functions in defense against biotic and abiotic stresses. Many of these compounds are glycosylated by family 1 glycosyltransferases (GTs). Oats (Avenaspp.) make root-derived antimicrobial triterpenes (avenacins) that provide protection against soil-borne diseases. The ability to synthesize avenacins has evolved since the divergence of oats from other cereals and grasses. The major avenacin, A-1, is acylated with N-methylanthranilic acid. Previously, we have cloned and characterized three genes for avenacin synthesis (for the triterpene synthase SAD1, a triterpene-modifying cytochrome P450 SAD2, and the serine carboxypeptidase-like acyl transferase SAD7), which form part of a biosynthetic gene cluster. Here, we identify a fourth member of this gene cluster encoding a GT belonging to clade L of family 1 (UGT74H5), and show that this enzyme is anN-methylanthranilic acid O-glucosyltransferase implicated in the synthesis of avenacin A-1. Two other closely related family 1 GTs (UGT74H6 and UGT74H7) are also expressed in oat roots. One of these (UGT74H6) is able to glucosylate both N-methylanthranilic acid and benzoic acid, whereas the function of the other (UGT74H7) remains unknown. Our investigations indicate that UGT74H5 is likely to be key for the generation of the activated acyl donor used by SAD7 in the synthesis of the major avenacin, A-1, whereas UGT74H6 may contribute to the synthesis of other forms of avenacin that are acylated with benzoic acid.

 

Crystallization and preliminary X-ray analysis of Pac17 from the pacidamycin-biosynthetic cluster of Streptomyces coeruleorubidus

Daniel R. Tromans ; Clare E. M. Stevenson ; Rebecca J. M. Goss ; David M. Lawson

Acta Cryst 2012, F68 971-974

Pac17 is an uncharacterized protein from the pacidamycin gene cluster of the soil bacterium Streptomyces coeruleorubidus. It is implicated in the biosynthesis of the core diaminobutyric acid residue of the antibiotic, although its precise role is uncertain at present. Given that pacidamycins inhibit translocase I of Pseudomonas aeruginosa, a clinically unexploited antibiotic target, they offer new hope in the search for antibacterial agents directed against this important pathogen. Crystals of Pac17 were grown by vapour diffusion and X-ray data were collected at a synchrotron to a resolution of 1.9 Å from a single crystal. The crystal belonged to space group C2, with unit-cell parameters a = 214.12, b = 70.88, c = 142.22 Å, [beta] = 92.96°. Preliminary analysis of these data suggests that the asymmetric unit consists of one Pac17 homotetramer, with an estimated solvent content of 49.0%.