Advance online publication:

This section includes articles accepted for publication in Microbial Cell, which have not been released in a regular issue, yet. Please note that the PDF versions of advance publication articles are generally paginated starting with page 1. This does not correspond to the final pagination upon release of the issue it will appear in.

 

Urm1, not quite a ubiquitin-like modifier?

Lars Kaduhr, Cindy Brachmann, Keerthiraju Ethiraju Ravichandran, James D. West, Sebastian Glatt and Raffael Schaffrath

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Ubiquitin related modifier 1 (Urm1) is a unique eukaryotic member of the ubiquitin-fold (UbF) protein family and conserved from yeast to humans. Urm1 is dual-functional, acting both as a sulfur carrier for thiolation of tRNA anticodons and as a protein modifier in a lysine-directed Ub-like conjugation also known as urmylation. Although Urm1 conjugation coincides with oxidative stress and targets proteins like 2-Cys peroxiredoxins from yeast (Ahp1) and fly (Prx5), it was unclear how urmylation proceeds molecularly and whether it is affected by the activity of these antioxidant enzymes. An in-depth study of Ahp1 urmylation in yeast from our laboratory (Brachmann et al., 2020) uncovered that promiscuous lysine target sites and specific redox requirements determine the Urm1 acceptor activity of the peroxiredoxin. The results clearly show that the dimer interface and the 2-Cys based redox-active centers of Ahp1 are affecting the Urm1 conjugation reaction. Together with in vivo assays demonstrating that high organic peroxide concentrations can prevent Ahp1 from being urmylated, Brachmann et al. provide insights into a potential link between Urm1 utilization and oxidant defense of cells. Here, we highlight these major findings and discuss wider implications with regards to an emerging link between Urm1 conjugation and redox biology. Moreover, from these studies we propose to redefine our perspective on Urm1 and the molecular nature of urmylation, a post-translational conjugation that may not be that ubiquitin-like after all.

PDF | Published online: 21/09/2021 | In press

Using microbial metalo-aminopeptidases as targets in human infectious diseases

Jorge González-Bacerio, Maikel Izquierdo, Mirtha Elisa Aguado, Ana C. Varela, Maikel González-Matos and Maday Alonso del Rivero

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Several microbial metalo-aminopeptidases are emerging as novel targets for the treatment of human infectious diseases. Some of them are well validated as targets and some are not; some are essential enzymes and others are important for virulence and pathogenesis. For another group, it is not clear if their enzymatic activity is involved in the critical functions that they mediate. But one aspect has been established: they display relevant roles in bacteria and protozoa that could be targeted for therapeutic purposes. This work aims to describe these biological functions for several microbial metalo-aminopeptidases.

PDF | Published online: 09/08/2021 | In press

Airborne bacteria in show caves from Southern Spain

Irene Dominguez-Moñino, Valme Jurado, Miguel Angel Rogerio-Candelera, Bernardo Hermosin and Cesareo Saiz-Jimenez

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This work presents a study on the airborne bacteria recorded in three Andalusian show caves, subjected to different managements. The main differences within the caves were the absence of lighting and phototrophic biofilms in Cueva de Ardales, the periodic maintenance and low occurrence of phototrophic biofilms in Gruta de las Maravillas, and the abundance of phototrophic biofilms in speleothems and walls in Cueva del Tesoro. These factors conditioned the diversity of bacteria in the caves and therefore there are large differences among the CFU m-3, determined using a suction impact collector, equipment widely used in aerobiological studies. The study of the bacterial diversity, inside and outside the caves, indicates that the air is mostly populated by bacteria thriving in the subterranean environment. In addition, the diversity seems to be related with the presence of abundant phototrophic biofilms, but not with the number of visitors received by each cave.

PDF | Supplemental Information | Published online: 26/07/2021 | In press

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