Ribosomal peptides with polycyclic isoprenoid moieties.

Isoprenoid modifications of proteins and peptides serve fundamental biological functions and are of therapeutic interest. While C (farnesyl) and C (geranylgeranyl) moieties are prevalent among proteins, known ribosomal peptide prenylations involve shorter-chain units not exceeding farnesyl in size. To our knowledge, cyclized terpene moieties have not been reported from either biomolecule class.

Methyltransferases from RiPP pathways: shaping the landscape of natural product chemistry.

This review article aims to highlight the role of methyltransferases within the context of ribosomally synthesised and post-translationally modified peptide (RiPP) natural products. Methyltransferases play a pivotal role in the biosynthesis of diverse natural products with unique chemical structures and bioactivities. They are highly chemo-, regio-, and stereoselective allowing methylation at various positions.

Opportunities and challenges of RiPP-based therapeutics.

Covering: up to 2024Ribosomally synthesised and post-translationally modified peptides (RiPPs) comprise a substantial group of peptide natural products exhibiting noteworthy bioactivities ranging from antiinfective to anticancer and analgesic effects. Furthermore, RiPP biosynthetic pathways represent promising production routes for complex peptide drugs, and the RiPP technology is well-suited for peptide engineering to produce derivatives with specific functions. Thus, RiPP natural products possess features that render them potentially ideal candidates for drug discovery and development.

Biomimetic S-Adenosylmethionine Regeneration Starting from Multiple Byproducts Enables Biocatalytic Alkylation with Radical SAM Enzymes.

S-Adenosylmethionine (SAM) is an enzyme cofactor involved in methylation, aminopropyl transfer, and radical reactions. This versatility renders SAM-dependent enzymes of great interest in biocatalysis. The usage of SAM analogues adds to this diversity.

Structural and Biochemical Insights into Post-Translational Arginine-to-Ornithine Peptide Modifications by an Atypical Arginase.

Landornamide A is a ribosomally synthesized and post-translationally modified peptide (RiPP) natural product with antiviral activity. Its biosynthetic gene cluster encodes─among other maturases─the peptide arginase OspR, which converts arginine to ornithine units in an unusual post-translational modification. Peptide arginases are a recently discovered RiPP maturase family with few characterized representatives.

Emulating nonribosomal peptides with ribosomal biosynthetic strategies.

Peptide natural products are important lead structures for human drugs and many nonribosomal peptides possess antibiotic activity. This makes them interesting targets for engineering approaches to generate peptide analogues with, for example, increased bioactivities. Nonribosomal peptides are produced by huge mega-enzyme complexes in an assembly-line like manner, and hence, these biosynthetic pathways are challenging to engineer.

A bicyclic -adenosylmethionine regeneration system applicable with different nucleosides or nucleotides as cofactor building blocks.

The ubiquitous cofactor -adenosyl-l-methionine (SAM) is part of numerous biochemical reactions in metabolism, epigenetics, and cancer development. As methylation usually improves physiochemical properties of compounds relevant for pharmaceutical use, the sustainable use of SAM as a methyl donor in biotechnological applications is an important goal. SAM-dependent methyltransferases are consequently an emerging biocatalytic tool for environmentally friendly and selective alkylations.

Posttranslationally Acting Arginases Provide a Ribosomal Route to Non-proteinogenic Ornithine Residues in Diverse Peptide Sequences.

Ornithine is a component of many bioactive nonribosomal peptides but is challenging to incorporate into ribosomal products. We recently identified OspR, a cyanobacterial arginase-like enzyme that installs ornithines in the antiviral ribosomally synthesised and posttranslationally modified peptide (RiPP) landornamide A. Here we report that OspR belongs to a larger family of peptide arginases from diverse organisms and RiPP types.

Round, round we go - strategies for enzymatic cofactor regeneration.

Covering: up to the beginning of 2020Enzymes depending on cofactors are essential in many biosynthetic pathways of natural products. They are often involved in key steps: catalytic conversions that are difficult to achieve purely with synthetic organic chemistry. Hence, cofactor-dependent enzymes have great potential for biocatalysis, on the condition that a corresponding cofactor regeneration system is available.

Chorismatases - the family is growing.

Chorismatases catalyse the cleavage of chorismate, yielding (dihydroxy-)benzoate derivatives, which often constitute starter units for pharmaceutically relevant secondary metabolites. Depending on their products, chorismatases have been classified into three different subfamilies. These can be assigned using a set of amino acid residues in the active site.

Several Polyphosphate Kinase 2 Enzymes Catalyse the Production of Adenosine 5'-Polyphosphates.

Polyphosphate kinases (PPKs) are involved in many metabolic processes; enzymes of the second family (PPK2) are responsible for nucleotide synthesis fuelled by the consumption of inorganic polyphosphate. They catalyse the phosphorylation of nucleotides with various numbers of phosphate residues, such as monophosphates or diphosphates. Hence, these enzymes are promising candidates for cofactor regeneration systems.

Substrate recognition and mechanism revealed by ligand-bound polyphosphate kinase 2 structures.

Inorganic polyphosphate is a ubiquitous, linear biopolymer built of up to thousands of phosphate residues that are linked by energy-rich phosphoanhydride bonds. Polyphosphate kinases of the family 2 (PPK2) use polyphosphate to catalyze the reversible phosphorylation of nucleotide phosphates and are highly relevant as targets for new pharmaceutical compounds and as biocatalysts for cofactor regeneration. PPK2s can be classified based on their preference for nucleoside mono- or diphosphates or both.

Asymmetric C-Alkylation by the S-Adenosylmethionine-Dependent Methyltransferase SgvM.

S-Adenosylmethionine-dependent methyltransferases (MTs) play a decisive role in the biosynthesis of natural products and in epigenetic processes. MTs catalyze the methylation of heteroatoms and even of carbon atoms, which, in many cases, is a challenging reaction in conventional synthesis. However, C-MTs are often highly substrate-specific.

Catalytic Alkylation Using a Cyclic S-Adenosylmethionine Regeneration System.

S-Adenosylmethionine-dependent methyltransferases are versatile tools for the specific alkylation of many compounds, such as pharmaceuticals, but their biocatalytic application is severely limited owing to the lack of a cofactor regeneration system. We report a biomimetic, polyphosphate-based, cyclic cascade for methyltransferases. In addition to the substrate to be methylated, only methionine and polyphosphate have to be added in stoichiometric amounts.

Functional and structural characterisation of a bacterial O-methyltransferase and factors determining regioselectivity.

Mg -dependent catechol-O-methyltransferases occur in animals as well as in bacteria, fungi and plants, often with a pronounced selectivity towards one of the substrate's hydroxyl groups. Here, we show that the bacterial MxSafC exhibits excellent regioselectivity for para as well as for meta methylation, depending on the substrate's characteristics. The crystal structure of MxSafC was solved in apo and in holo form.

Regiocomplementary O-Methylation of Catechols by Using Three-Enzyme Cascades.

S-Adenosylmethionine (SAM)-dependent enzymes have great potential for selective alkylation processes. In this study we investigated the regiocomplementary O-methylation of catechols. Enzymatic methylation is often hampered by the need for a stoichiometric supply of SAM and the inhibitory effect of the SAM-derived byproduct on most methyltransferases.

Cinnamic acid derivatives as inhibitors for chorismatases and isochorismatases.

Chorismatases and isochorismatases catalyse the hydrolysis of chorismate or isochorismate leading to unsaturated cyclohexenoic acid derivatives. Based on simplification of the physiological substrates, two cinnamic acid-derived compounds, differing in the saturation of the side chain, were developed. In contrast to earlier inhibitor studies, the compounds described here do not have an ether bond and therefore can be synthesised very easily in one or two steps without the need for protective groups.