Biology subjects

Lange, H.

Publications and source records attributed to Lange, H..

5 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↗

bioRxiv2023

An annual gene expression profile of markers for programmed cell death and polyphenols biosynthesis across heartwood forming stems in Robinia pseudoacacia

Heartwood formation is a developmental defense strategy in trees that transforms the inner stem core through the deposition of natural antimicrobial preservatives. The defining cellular events in this process are the accumulation of specialized metabolites conjoined with the death of living cells in the transition zone. While previous studies have characterized heartwood compounds and deposition, the cell death aspects are often neglected. Thus, the correlation of these defining cellular events remained unclear, while the exact timing of occurrence and regional involvement within the stem became topics for debate. In this study, members of metacaspases and vacuolar processing enzymes were isolated as programmed cell death (PCD) markers to explore their correlation with those of polyphenol biosynthesis. We collected heartwood-forming stems from R. pseudoacacia monthly for a year and monitored their expression through real-time PCR. Our results revealed novel markers of PCD in xylem parenchyma cells and demonstrated their corresponding fluctuation in expression with markers of polyphenols across the stem regions. The annual expression profile demonstrated regional stem development along with weather data on a monthly scale. This work provides a framework to compare the xylem-specific PCD in stages of stem development and a preliminary overview of how they correspond to external conditions over an annual cycle.

plant biology↗

bioRxiv2022

Effect of chemical modifications of tannins on their antibiofilm effect against Gram-negative and Gram-positive bacteria

(1) BackgroundTannins have demonstrated antibacterial and antibiofilm activity, but the mechanisms of action are not completely elucidated. We are interested in understanding how to modulate the antibiofilm activity of tannins and in delineating the relationship between chemical determinants and antibiofilm activity. (2) Materials and methodsthe effect of five different naturally acquired tannins and their chemical derivatives on biofilm formation and planktonic growth of Salmonella Typhimurium, Pseudomonas aeruginosa, Escherichia coli and Staphylococcus aureus was determined in the Calgary biofilm device. (3) Resultsmost of the unmodified tannins exhibited specific antibiofilm activity against the assayed bacteria. The chemical modifications were found to alter the antibiofilm activity level and spectrum of the tannins, with the positive charge introducing C3NMe3Cl-0.5 derivatization shifting the anti-biofilm spectrum towards Gram-negative bacteria and C3NMe3Cl-0.1 and the acidifying CH3COOH derivatization shifting the spectrum towards Gram-positive bacteria. Also, the quantity of phenolic-OH groups per molecule has a weak impact on the anti-biofilm activity of the tannins. (4) Conclusionswe were able to modulate the antibiofilm activity of several tannins by specific chemical modifications, providing a first approach for fine tuning of their activity and spectrum.

microbiology↗

bioRxiv2020

SERRATE interacts with the nuclear exosome targeting (NEXT) complex to degrade primary miRNA precursors in Arabidopsis

SERRATE/ARS2 is a conserved RNA effector protein involved in transcription, processing and export of different types of RNAs. In Arabidopsis, the best-studied function of SERRATE (SE) is to promote miRNA processing. Here, we report that SE interacts with the Nuclear Exosome Targeting (NEXT) complex, comprising the RNA helicase HEN2, the RNA binding protein RBM7 and one of the two zinc-knuckle proteins ZCCHC8A/ZCCHC8B. The identification of common targets of SE and HEN2 by RNA-seq supports the idea that SE cooperates with NEXT for RNA surveillance by the nuclear exosome. Among the RNA targets accumulating in absence of SE or NEXT are miRNA precursors. Loss of NEXT components results in the accumulation of pri-miRNAs without affecting levels of miRNAs, indicating that NEXT is, unlike SE, not required for miRNA processing. As compared to se-2, se-2 hen2-2 double mutants showed increased accumulation of pri-miRNAs, but partially restored levels of mature miRNAs and attenuated developmental defects. We propose that the slow degradation of pri-miRNAs caused by loss of HEN2 compensates for the poor miRNA processing efficiency in se-2 mutants, and that SE regulates miRNA biogenesis through its double contribution in promoting miRNA processing but also pri-miRNA degradation through the recruitment of the NEXT complex.

plant biology↗

bioRxiv2019

RST1 and RIPR connect the cytosolic RNA exosome to the Ski complex in Arabidopsis

The RNA exosome is a key 3-5 exoribonuclease with an evolutionarily conserved structure and function. Its cytosolic functions require the co-factors SKI7 and the Ski complex. Here we demonstrate by co-purification experiments that the ARM repeat protein RESURRECTION1 (RST1) and RST1 INTERACTING PROTEIN (RIPR) connect the cytosolic Arabidopsis RNA exosome to the Ski complex. rst1 and ripr mutants accumulate RNA quality control siRNAs (rqc-siRNAs) produced by the post-transcriptional gene silencing (PTGS) machinery when mRNA degradation is compromised. The small RNA populations observed in rst1 and ripr mutants are also detected in mutants lacking the RRP45B/CER7 core exosome subunit. Thus, molecular and genetic evidence supports a physical and functional link between RST1, RIPR and the RNA exosome. Our data reveal the existence of additional cytosolic exosome co-factors besides the known SKI subunits. RST1 is not restricted to plants, as homologues with a similar domain architecture but unknown function exist in animals, including humans.

molecular biology↗