Biology subjects

Frese, A.

Publications and source records attributed to Frese, A..

3 recordsLinked to original sources

bioRxiv2025

Engineered Proteins Mimic ssRNA Phage to Disrupt Type IV Pili

Antimicrobial resistance is a growing global health crisis, with ESKAPE pathogens, such as Acinetobacter species, contributing significantly to hospital-acquired infections. These bacteria employ various virulence factors, including extracellular type IV pili (T4P), which serve as essential appendages for DNA uptake, biofilm formation, and resistance to antibiotics. Single-stranded RNA (ssRNA) bacteriophages (phages) exploit these retractile pili as entry receptors, but the exact mechanism of viral RNA delivery following pilus binding and retraction remains poorly understood. In this study, we investigated the entry mechanism of the ssRNA phage AP205 by identifying the specific phage components necessary for T4P detachment, a key step in viral genome entry. Our data reveals the phages maturation protein (Mat) is sufficient to induce pilus detachment on its own, and the overall virion structure further enhances the efficiency of this process. These findings provide mechanistic insights into how ssRNA phages exploit bacterial T4P as part of their infection pathway and suggest a conserved strategy for host entry. ImportanceAcinetobacter species are widespread environmental bacteria and members of the ESKAPE group of pathogens, often associated with hospital-acquired infections amongst immunocompromised patients. A major reason for the increase in antibiotic resistance in Acinetobacter species is its use of T4P to evade antibiotic treatment. With antibiotic resistance becoming a global health crisis, targeting these virulence factors represents a promising approach to combat infections. Since T4P are critical for Acinetobacter virulence, understanding mechanisms that can disrupt them is highly important. ssRNA phages provide a natural model for this, as they can target T4P to initiate infection. Recent research has shown that ssRNA phages can detach pili during their infection process. However, the precise mechanism behind this phenomenon remains unknown. Our research addresses part of this knowledge gap by identifying the key components required for this pilus detachment. This work will enhance the current understanding of the virulent T4P in Acinetobacter species, which could ultimately lead to broader medical advancements.

microbiology↗

bioRxiv2024

Developmental editing control of mRNA ND7 involves KREH2 helicase-dependent gRNAselection and proposed RNA structure in Trypanosoma brucei

Unknown factors regulate mitochondrial U-insertion/deletion (U-indel) RNA editing in procyclic-form (PCF) and bloodstream-form (BSF) T. brucei. This editing, directed by anti-sense gRNAs, creates canonical protein-encoding mRNAs and may developmentally control respiration. Canonical editing by gRNAs that specify protein-encoding mRNA sequences occurs amid massive non-canonical editing of unclear sources and biological significance. We found PCF-specific repression at a major early checkpoint in mRNA ND7, involving helicase KREH2-dependent opposite modulation of canonical and non-canonical "terminator" gRNA utilization. Terminator-programmed editing derails canonical editing and installs proposed repressive structure in 30% of the ND7 transcriptome. BSF-to-PCF differentiation in vitro recreated this negative control. Remarkably, KREH2-RNAi knockdown relieved repression and increased editing progression by reverting canonical/terminator gRNA utilization. ND7 transcripts lacking early terminator-directed editing in PCF exhibited similar negative editing control along the mRNA sequence, suggesting global modulation of gRNA utilization fidelity. The terminator is a "moonlighting" gRNA also associated with mRNA COX3 canonical editing, so the gRNA transcriptome seems multifunctional. Thus, KREH2 is the first identified repressor in developmental editing control. This and our prior work support a model whereby KREH2 activates or represses editing in a stage and substrate-specific manner. KREH2s novel dual role tunes mitochondrial gene expression in either direction during development.

molecular biology↗

bioRxiv2019

Increasing motor skill acquisition by driving theta-gamma coupling

Skill learning is a fundamental adaptive process, but the mechanisms remain poorly understood. Hippocampal learning is closely associated with gamma activity, which is amplitude-modulated by the phase of underlying theta activity. Whether such nested activity patterns also underpin skill acquisition in non-hippocampal tasks is unknown. Here we addressed this question by using transcranial alternating current stimulation (tACS) over sensorimotor cortex to modulate theta-gamma activity during motor skill acquisition, as an exemplar of a non-hippocampal-dependent task. We demonstrated, and then replicated, a significant improvement in skill acquisition with theta-gamma tACS, which outlasted the stimulation by an hour. Our results suggest that theta-gamma activity may be a common mechanism for learning across the brain and provides a putative novel intervention for optimising functional improvements in response to training or therapy.

neuroscience↗