Biology subjects

Albers, S. V.

Publications and source records attributed to Albers, S. V..

3 recordsLinked to original sources

bioRxiv2025

(R)-S-Adenosyl-L-methionine hydrolases counter sulfonium epimerisation in thermophilic archaea

S-Adenosyl-L-methionine (SAM) is the second most used enzyme cofactor and vital for numerous cellular reactions such as methylation or polyamine synthesis. While most stereocentres of the biologically active (SS,SC)-SAM are fixed, epimerisation at the methyl sulfonium centre is driven by heat, yielding biologically inactive (RS,SC)-SAM. This SAM diastereomer disturbs SAM-dependent pathways, posing a metabolic threat especially to thermophilic organisms. In vitro analysis shows that SAM hydrolases cleave the biologically inactive (RS,SC)-SAM, thereby constituting to a metabolic salvage pathway. For further analysis of the biological relevance, we characterised two archaeal SAM hydrolases from the thermophilic Sulfolobus acidocaldarius and the halophilic Haloferax volcanii, confirming their selectivity towards (RS,SC)-SAM in vitro. Genetic manipulation in the native hosts supports a significant role of the SAM-hydrolases in decreasing the share of intracellular (RS,SC)-SAM to sustain cellular functions in thermophilic organisms.

biochemistry↗

bioRxiv2024

New components of the community based DNA-repair mechanism in Sulfolobales

After exposure to UV light, Sulfolobus acidocaldarius cells aggregate in a species-specific manner to exchange DNA and repair double-strand breaks via homologous recombination. The formation of cell-cell interactions is mediated by Ups pili. DNA exchange subsequently occurs through the Ced system, which imports DNA. To identify novel players in these processes, we investigated several genes upregulated after UV exposure by creating in-frame deletion mutants and performing cell aggregation and DNA exchange assays. This led to the identification of two novel components involved in the Ups and Ced systems: UpsC, a minor pilin of the Ups pili, and CedD, a VirD4-like ATPase essential for DNA import. Altogether, these findings provide new insights into the fascinating DNA damage response of Sulfolobales.

microbiology↗

bioRxiv2019

Architecture and modular assembly of the Sulfolobus S-layers revealed by electron cryo-tomography

Surface protein layers (S-layers) often form the only structural component of the archaeal cell wall and are therefore important for cell survival. S-layers have a plethora of cellular functions including maintenance of cell shape, osmotic and mechanical stability, the formation of a semi-permeable protective barrier around the cell, cell-cell interaction, as well as surface adhesion. Despite the central importance of the S-layer for archaeal life, their three-dimensional architecture is still poorly understood. Here we present the first detailed 3D electron cryo-microscopy maps of archaeal S-layers from three different Sulfolobus strains. We were able to pinpoint the positions and determine the structure of the two subunits SlaA and SlaB. We also present a model describing the assembly of the mature S-layer.

microbiology↗