Biology subjects

Weber, M. M.

Publications and source records attributed to Weber, M. M..

3 recordsLinked to original sources

bioRxiv2023

Chromosome-level genome assembly for the angiosperm Silene conica

The angiosperm genus Silene has been the subject of extensive study in the field of ecology and evolution, but the availability of high-quality reference genome sequences has been limited for this group. Here, we report a chromosome-level assembly for the genome of Silene conica based on PacBio HiFi, Hi-C and Bionano technologies. The assembly produced 10 scaffolds (one per chromosome) with a total length of 862 Mb and only [~]1% gap content. These results confirm previous observations that S. conica and its relatives have a reduced base chromosome number relative to the genuss ancestral state of 12. Silene conica has an exceptionally large mitochondrial genome (>11 Mb), predominantly consisting of sequence of unknown origins. Analysis of shared sequence content suggests that it is unlikely that transfer of nuclear DNA is the primary driver of this mitochondrial genome expansion. More generally, this assembly should provide a valuable resource for future genomic studies in Silene, including comparative analyses with related species that recently evolved sex chromosomes. SignificanceWhole-genome sequences have been largely lacking for species in the genus Silene even though these flowering plants have been used for studying ecology, evolution, and genetics for over a century. Here, we address this gap by providing a high-quality nuclear genome assembly for S. conica, a species known to have greatly accelerated rates of sequence and structural divergence in its mitochondrial and plastid genomes. This resource will be valuable in understanding the coevolutionary interactions between nuclear and cytoplasmic genomes and in comparative analyses across this highly diverse genus.

genomics↗

bioRxiv2022

The Chlamydia trachomatis type III secreted effector protein CteG induces centrosome amplification through interactions with centrin-2

The centrosome is the main microtubule organizing center of the cell and is crucial for mitotic spindle assembly, chromosome segregation, and cell division. Centrosome duplication is tightly controlled, yet several pathogens, most notably oncogenic viruses, perturb this process leading to increased centrosome numbers. Infection by the obligate intracellular pathogen Chlamydia trachomatis (C.t.) correlates with blocked cytokinesis, supernumerary centrosomes, and multipolar spindles; however, the mechanisms behind how C.t. induces these cellular abnormalities from the confines of its inclusion, remain largely unknown. Here we show that the type III secreted effector protein, CteG, binds to centrin-2 (CETN2), a key structural component of centrosomes and regulator of centriole duplication. This interaction requires a functional calcium binding EF hand 4 of CETN2, which is recognized via the C-terminus of CteG. Significantly, we show that deletion of CteG, or knockdown of CETN2, significantly impairs chlamydias ability to induce centrosome amplification. Uniquely, we have identified the first bacterial effector to target centrins, crucial regulators of the eukaryotic cell cycle. These findings have not only allowed us to begin addressing how C.t. induces gross cellular abnormalities during infection, but also indicate that obligate intracellular bacteria may contribute to cellular transformation events that negatively impact host physiology even when the pathogen is long removed. Understanding the consequences of CteG-CETN2 interactions, its impact on centrosome amplification, and the long-term effect this has on host cells could explain why chlamydial infection leads to an increased risk of cervical or ovarian cancer. Significance StatementThe presence of more than two centrosomes is a hallmark of many types of cancer, including cervical and ovarian cancers of which Chlamydia trachomatis (C.t.) infection is a significant risk factor. Despite the importance of this problem, how C.t. orchestrates these drastic changes in the host cell remains poorly understood. Here, we describe how C.t. uses a single effector protein, CteG, to drive centrosome amplification via manipulation of a key regulator of centriole duplication, centrin-2. This work begins to define how C.t. induces centrosome amplification to promote its replication while potentially contributing to devastating long-term negative consequences for normal host physiology. Further it may help elucidate why chlamydial infection leads to an increased cancer risk.

microbiology↗

bioRxiv2021

A conserved uORF impacts APOBEC3G translation and is essential for translational inhibition by the HIV-1 Vif protein

The HIV-1 Vif protein is essential for viral fitness and pathogenicity. Vif decreases expression of cellular restriction factors APOBEC3G (A3G), A3F, A3D and A3H, which inhibit HIV-1 replication by inducing hypermutation during reverse transcription. Vif counteracts A3G at several levels (transcription, translation and protein degradation) that together reduce the levels of A3G in cells and prevent its incorporation into viral particles. How Vif affects A3G translation remains unclear. Here, we uncovered the importance of a short conserved uORF (upstream ORF) located within two critical stem-loop structures of the 5 untranslated region (5UTR) of A3G mRNA for this process. A3G translation occurs through a combination of leaky-scanning and translation re-initiation and the presence of an intact uORF decreases the extent of global A3G translation under normal conditions. Interestingly, the uORF is also absolutely required for Vif-mediated translation inhibition and redirection of A3G mRNA into stress granules. Overall, we discovered that A3G translation is regulated by a small uORF conserved in the human population and that Vif uses this specific feature to repress its translation.

microbiology↗