Biology subjects

Seebeck, F. P.

Publications and source records attributed to Seebeck, F. P..

3 recordsLinked to original sources

bioRxiv2026

Ovothiol A mediates singlet oxygen resistance and acclimation in Chlamydomonas

Light is essential for photosynthetic organisms, but excess light can generate toxic levels of reactive oxygen species (ROS). To neutralize these ROS, plants and algae produce a variety of antioxidants like carotenoids, tocopherols, and glutathione. However, the role of alternative ROS scavengers, such as ovothiols, has not been studied in the context of oxidative stress in photosynthetic organisms. Here, we report that many algal groups have the potential for the biosynthesis of ovothiols, a group of thiohistidines. We discovered that the model green microalga Chlamydomonas reinhardtii produces millimolar concentrations of ovothiol A, whose biosynthesis is mediated by the ovothiol synthase OVOA1. Using CRISPR-generated ovoa1 knockout mutants, we found that ovothiol production is essential for resistance and acclimation to singlet oxygen, a prominent ROS in photosynthetic organisms. Finally, we demonstrated that OVOA1 expression is activated by singlet oxygen and light signaling pathways in which we identified the major regulatory factors. Overall, our results show that ovothiol A is a major, previously overlooked antioxidant in Chlamydomonas. This work broadens our understanding of cellular mechanisms that combat the damaging effects of oxidative stress. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=200 SRC="FIGDIR/small/702910v2_ufig1.gif" ALT="Figure 1"> View larger version (54K): org.highwire.dtl.DTLVardef@cddb9corg.highwire.dtl.DTLVardef@10d0a43org.highwire.dtl.DTLVardef@11cc087org.highwire.dtl.DTLVardef@a40cc5_HPS_FORMAT_FIGEXP M_FIG C_FIG

plant biology↗

bioRxiv2025

A robust platform streamlining aromatic noncanonical amino acid biosynthesis and genetic code expansion in E. coli

Genetic code expansion has significantly enhanced the diversity and functionality of proteins in the biological world, leading to a wide range of applications in catalysis, biology, and medicine. Despite the extraordinary advances in genetic code expansion over the past years, the availability and cost of noncanonical amino acids (ncAAs) remain one of the major obstacles, particularly for large-scale industrial production. In situ biosynthesis of ncAAs from commercially available precursors offers a promising solution to this challenge, yet only a few biosynthetic pathways for specific amino acids have been reported to date. To address this gap, we present a robust platform that couples the biosynthesis of aromatic amino acids with genetic code expansion in E. coli, enabling the production of proteins and peptides containing incorporated ncAAs. Forty amino acids with diverse functional groups were synthesized from aryl aldehydes by a biosynthetic pathway comprising two heterologously expressed enzymes and one endogenous enzyme. Nineteen of these amino acids were successfully incorporated into superfolder GFP (sfGFP) using three classic orthogonal translation systems. The platforms versatility was further demonstrated by the production of macrocyclic peptides and antibodies containing functional ncAAs, such as para-azidophenylalanine and para-boronophenylalanine. We envision that the simplicity, efficiency, compatibility, and broad applicability of this biosynthetic pathway and the platform will greatly facilitate the production of peptides, enzymes, and antibodies containing ncAAs, thereby accelerating their use in various applications. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=175 SRC="FIGDIR/small/631627v1_ufig1.gif" ALT="Figure 1"> View larger version (52K): org.highwire.dtl.DTLVardef@8a6d2eorg.highwire.dtl.DTLVardef@5f8b9org.highwire.dtl.DTLVardef@c514aorg.highwire.dtl.DTLVardef@acd66d_HPS_FORMAT_FIGEXP M_FIG C_FIG

synthetic biology↗

bioRxiv2022

Biomimetic S-adenosylmethionine regeneration for nucleophilic and radical alkylation reactions and aminopropyltransfer

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. However, high cost and instability of the cofactor impedes the investigation and usage of these enzymes. While SAM regeneration protocols from the methyltransferase (MT) byproduct S-adenosylhomocysteine are available, aminopropyl transferases and radical SAM enzymes are not covered. Here, we report an efficient one-pot system to supply or regenerate SAM and SAM analogues for all three enzyme classes. The systems flexibility is showcased by the transfer of an ethyl group with a cobalamin-dependent radical SAM MT using S-adenosylethionine as a cofactor. This shows the potential of SAM (analogue) supply and regeneration for the application of diverse chemistry, as well as for mechanistic studies using cofactor analogues.

biochemistry↗