Complex structures of MoeN5 with substrate analogues suggest sequential catalytic mechanism

Structural diversity, bioactivity, and biosynthesis of phosphoglycolipid family antibiotics: recent advances

Moenomycins, such as moenomycin A, are phosphoglycolipid specialized metabolites produced by a number of actinobacterial species. They are among the most potent antibacterial compounds known to date, which drew numerous studies directed at various aspects of the chemistry and biology of moenomycins. In this review, we outline the advances in moenomycin research over the last decade. We focus on biological aspects, highlighting the contribution of the novel methods of genomics and molecular biology to the deciphering of the biosynthesis and activity of moenomycins. Specifically, we describe the structural diversity of moenomycins as well as the underlying genomic variations in moenomycin biosynthetic gene clusters. We also describe the most recent data on the mechanism of action and assembly of complicated phosphoglycolipid scaffold. We conclude with the description of the genetic control of moenomycin production by Streptomyces bacteria and a brief outlook on future developments.

Structural insights to a bi-functional isoprenyl diphosphate synthase that can catalyze head-to-tail and head-to-middle condensation

Isoprenoids represent the largest group of natural products, whose basal skeletons are synthesized by various isoprenyl diphosphate synthases (IDSs). As majority of IDSs catalyze head-to-tail reaction to produce linear form isoprenoids, some catalyze head-to-middle reaction to produce branched form products. In a previous study, an IDS termed MA1831 from Methanosarcina acetivorans was found to be capable of catalyzing both types of reaction. In addition to the canonical linear product of C₃₅ in length, MA1831 also catalyzes head-to-middle condensation of farnesyl diphosphate (FPP) and dimethylallyl diphosphate (DMAPP) to produce geranyllavandulyl diphosphate. In order to investigate the mechanism of action of MA1831, we determined its crystal structures in apo-form and in complex with substrates and analogues. The complex structures that contain isopentenyl S-thiolodiphosphate and DMAPP as homoallylic substrates were also reported, which should represent the reaction modes of MA1831-mediated head-to-tail and head-to-middle reaction, respectively. Based on the structural information, the mechanism of MA1831 catalyze head-to-tail and head-to-middle condensation reaction was proposed.

Bisphosphonate-Based Molecules as Potential New Antiparasitic Drugs

Neglected tropical diseases such as Chagas disease and leishmaniasis affect millions of people around the world. Both diseases affect various parts of the globe and drugs traditionally used in therapy against these diseases have limitations, especially with regard to low efficacy and high toxicity. In this context, the class of bisphosphonate-based compounds has made significant advances regarding the chemical synthesis process as well as the pharmacological properties attributed to these compounds. Among this spectrum of pharmacological activity, bisphosphonate compounds with antiparasitic activity stand out, especially in the treatment of Chagas disease and leishmaniasis caused by Trypanosoma cruzi and Leishmania spp., respectively. Some bisphosphonate compounds can inhibit the mevalonate pathway, an essential metabolic pathway, by interfering with the synthesis of ergosterol, a sterol responsible for the growth and viability of these parasites. Therefore, this review aims to present the information about the importance of these compounds as antiparasitic agents and as potential new drugs to treat Chagas disease and leishmaniasis.

Crystal structure of TchmY from Actinoplanes teichomyceticus

Moenomycin-type antibiotics are phosphoglycolipids that are notable for their unique modes of action and have proven to be useful in animal nutrition. The gene clusters tchm from Actinoplanes teichomyceticus and moe from Streptomyces are among a limited number of known moenomycin-biosynthetic pathways. Most genes in tchm have counterparts in the moe cluster, except for tchmy and tchmz, the functions of which remain unknown. Sequence analysis indicates that TchmY belongs to the isoprenoid enzyme C2-like superfamily and may serve as a prenylcyclase. The enzyme was proposed to be involved in terminal cyclization of the moenocinyl chain in teichomycin, leading to the diumycinol chain of moenomycin isomers. Here, recombinant TchmY protein was expressed in Escherichia coli and its crystal structure was solved by SIRAS. Structural analysis and comparison with other prenylcyclases were performed. The overall fold of TchmY consists of an (α/α)6-barrel, and a potential substrate-binding pocket is found in the central chamber. These results should provide important information regarding the biosynthetic basis of moenomycin antibiotics.