Biology subjects

Moerl, M.

Publications and source records attributed to Moerl, M..

3 recordsLinked to original sources

bioRxiv2026

A little feat in translation: miniaturized tRNAs in nematode and arachnid mitochondria

Transfer RNAs carry a highly conserved, cloverleaf-like secondary structure, which is essential to fulfill their task as adaptor molecules in translation. However, in mitochondria of metazoans, tRNA molecules were identified that deviate from this consensus structure and lack either the D- or T-arm, or, in some extreme cases, even both arms. These deviations are predominantly found in nematodes and arachnids, where in many cases the entire set of 22 mt tRNA genes are predicted to encode for such aberrant tRNAs or where even the complete loss of tRNA genes is proposed. Due to this unusual composition, we analyzed and characterized the mt tRNA pool of one representative of both groups. We identified the whole set of mt tRNAs and reannotated several tRNAs that differ significantly from previous genome-based predictions. In some cases, the sequence reads indicate putative tRNA editing events, showing that predictions exclusively based on mitogenome data have only a limited reliability. Our data also provide first insights into the modification pattern of such hairpin-like tRNAs.

Molecular Biology↗

bioRxiv2026

Functional class 2 CCA-adding enzymes in Asgard archaea and their implications for eukaryogenesis

CCA-adding enzymes are essential for transfer RNA (tRNA) maturation and translation among all domains of life. A long-standing dogma holds that archaea encode exclusively class one CCA-adding enzymes (CCA1), whereas bacteria and eukaryotes encode class two enzymes (CCA2), creating a perceived strict evolutionary separation between archaeal and eukaryotic CCA-adding enzymes. Here, we show that this view is incorrect. We identify widespread CCA2 enzymes across multiple archaeal superphyla, including Asgard archaea, and demonstrate that these enzymes are functional enzymes and can replace their archaeal CCA1 counterparts. Within Heimdallarchaeia, the proposed closest archaeal relatives of eukaryotes, we identify distinct clades with different CCA-adding enzyme repertoires that trace back to independent bacterial sources. One Heimdallarchaeia lineage exhibits strongest similarity to Bacteroidota/Chlorobiota/Rhodothermota, a bacterial group previously implicated in early gene contributions to eukaryogenesis. CCA-adding enzymes from early-branching eukaryotes share this deep signature, indicating that predecessors of the eukaryotic enzymes had already been long-established and functionally adapted within the ancestral Asgardian gene pool. Together, these findings challenge a central paradigm of CCA-adding enzyme evolution and provide molecular-level support for the ancestral integration and subsequent transmission of bacterial functions prior to or during eukaryogenesis, aligning with current evolutionary frameworks such as the Heimdall nucleation-decentralized innovation-hierarchical import (HDH) model.

evolutionary biology↗

bioRxiv2020

Monitoring the production of high diffraction-quality crystals of two enzymes in real time using in situ dynamic light scattering

The reproducible preparation of well diffracting crystals is a prerequisite for every structural study based on crystallography. An instrument called the XtalController has recently been designed that allows the monitoring of crystallization assays using dynamic light scattering and microscopy, and integrates piezo pumps to alter the composition of the mother liquor during the experiment. We have applied this technology to study the crystallization of two enzymes, the CCA-adding enzyme of the psychrophilic bacterium Planococcus halocryophilus and the hen egg white lysozyme in the presence of a synthetic chemical nucleant. We were able to i) detect early nucleation events and ii) drive the crystallization system (through cycles of dissolution/crystallization) towards growth conditions yielding crystals with excellent diffraction properties. This technology opens a way to the rational production of samples for crystallography, ranging from nanocrystals for electron diffraction, microcrystals for serial or conventional X-ray diffraction, to larger crystals for neutron diffraction.

biochemistry↗