Biology subjects

Torring, T.

Publications and source records attributed to Torring, T..

6 recordsLinked to original sources

bioRxiv2026

An Unusual Follower Peptide is Required for Biosynthesis of the Antibiotic Lasso Peptide Triculamin

Triculamin is a potent antibiotic lasso peptide first isolated in 1967. Previous studies have demonstrated that its biosynthesis follows a non-canonical logic unlike any other lasso peptide. In this study, we investigate the role of the unusual follower peptide and demonstrate that it is essential for efficient biosynthesis. Using structural prediction and targeted mutations of key conserved residues, we hypothesize that the interactions between the follower peptide and the macrocyclase create an enzyme-substrate complex that ensures delivery of the core peptide to the enzyme active site. Moreover, we demonstrate that analogs of the lasso peptide can be produced by modifying the core peptide, highlighting the substrate promiscuity of the lasso macrocyclase and identifying lysine-3 in the lasso peptide ring as the site of acetylation. Lastly, we achieve successful heterologous expression in Burkholderia sp. FERM 3421, which proves to be a superior heterologous host.

synthetic biology↗

bioRxiv2025

Biosynthesis, Structure, and Antibiotic Properties of Gelatinamin A, a Triculamin-like Lasso Peptide

Lasso peptides are structurally unique natural products endowed with high thermal and proteolytic stability, making them attractive as scaffolds for drug discovery. Recently, a new class of lasso peptides containing a second macrocycle, formed between a lysine sidechain and the C-terminus, was discovered, resulting in an even more compact architecture. Here, we report the first NMR structure of the class V lasso peptide, gelatinamin A. Using heterologous expression of the gelatinamin biosynthetic gene cluster (BGC) in Bacillus subtilis, we delineated the biosynthetic pathway through targeted gene deletions. We expressed and characterized the predicted transpeptidase, GelP, that catalyzes the formation of an isopeptide bond between Lys2 and the C-terminus and mediates the reversible conversion of gelatinamin B to gelatinamin A. In addition, we characterize GelT, an N-acetyltransferase that inactivates lasso peptide antimicrobial activity by acetylating a key lysine residue. Furthermore, we demonstrate that gelatinamin is highly potent against several important pathogens and that the activity is strongly bicarbonate-dependent. Finally, we propose a complete biosynthetic pathway for gelatinamin. The structural insight of gelatinamin A and the functional characterization of GelP provide the foundation for future discovery of class V lasso peptides and for engineering transpeptidases to modify other lasso peptide scaffolds.

biochemistry↗

bioRxiv2024

Convergent Evolution of the Antimycobacterial Lasso Peptide Triculamin

Triculamin is a ribosomally synthesized and post-translationally modified peptide (RiPP) lasso peptide with potent antimycobacterial activity, produced by an unusual, non-canonical biosynthetic gene cluster (BGC). In this study, we elucidate the biosynthetic pathway of triculamin through heterologous expression and show that the biosynthesis proceeds in the presence of a precursor (triA), macrocyclase (triC), and acetyltransferase (triT). Through in vitro triT acetylation and bioactivity assays, we show that acetylation functions as a resistance mechanism. Genomic searches of triculamin BGC genes across bacteria show that triculamin is more widely distributed than previously anticipated, as triculamin-like core peptides are found in at least three phyla in contrast to previously described lasso peptides that are typically restricted to one phylum. Triculamin BGCs with both canonical and non-canonical RiPP biosynthetic genes were identified. Two strains containing canonical triculamin-like BGCs were chemically characterized and shown to produce the novel triculamin-like lasso peptides palmamin and gelatinamin, the latter of which appears to have an unprecedented additional ring formation. Detailed phylogenetic investigation of the macrocyclases from triculamin-like BGCs suggests that these molecules are products of convergent evolution. These findings broaden the evolutionary and functional landscape of lasso peptides, revealing their unexpected diversification and cross-phylum distribution.

biochemistry↗

bioRxiv2023

Using LanM Enzymes to Modify Glucagon-Like Peptides 1 and 2 in E.coli

Selective modification of peptides is often exploited to improve pharmaceutically relevant properties of bioactive peptides like stability, circulation time, and potency. In Nature, natural products belonging to the class of ribosomally synthesized and post-translationally modified peptides (RiPPs) are known to install a number of highly attractive modifications with high selectivity. These modifications are installed by enzymes guided to the peptide by corresponding leader peptides removed as the last step of biosynthesis. Here, we exploit leader peptides and their matching enzymes to investigate the installment of D-Ala post-translationally in a critical position in the hormones, glucagon-like peptides (GLP) 1 and 2. We also offer insight into how precursor peptide design can modulate the modification pattern achieved.

synthetic biology↗

bioRxiv2023

Polyether ionophore antibiotics target drug-resistant clinical isolates, persister cells, and biofilms

Polyether ionophores are complex natural products known to transport various cations across biological membranes. While several members of this family are used in agriculture, e.g. as anti-coccidiostats, and have potent antibacterial activity, they are not currently pursued as antibiotics for human use. Polyether ionophores are typically grouped as having similar functions, despite the fact that they differ significantly in structure, and for this reason, it remains unclear how structure and activity are related. To triage whether certain members of the family constitute particularly interesting springboards for in-depth investigations, and future synthetic optimization, we here conduct a systematic comparative study of nine different polyether ionophores for their potential as antibiotics. This includes clinical isolates from bloodstream infections and studies of the compounds effects on bacterial biofilms and persister cells. We uncover distinct differences within the compound class and identify the compounds lasalocid, calcimycin, and nanchangmycin as having particularly interesting activity profiles for further development.

microbiology↗

bioRxiv2021

ColFeatures: Automated data extraction and classification of bacterial colonies

Examining microbial colonies on agar plates have been at the core of microbiology for many decades. It is usually done manually, and therefore subject to bias besides requiring a considerable amount of time and effort. In order to optimize and standardize the identification of bacterial colonies growing on agar plates, we have developed an open access tool available on GitHub: ColFeatures. The software allows automated identification of bacterial colonies, extracts key morphological data and generate labels that ensure tracking of temporal development. We included machine learning algorithms that provide sorting of environmental isolates by using cluster methodologies. Furthermore, we show how cluster performance is evaluated using index scores (Silhouette, Calinski-Harabasz, Davies-Bouldin) to ensure the outcome of colony classification. As automation becomes more prominent in microbiology, tools as ColFeatures will assist identification of bacterial colonies on agar plates, bypassing human bias and complementing sequencing or mass spectrometry information that often comes attached with a considerable price tag.

microbiology↗