Biology subjects

Hardy, A.

Publications and source records attributed to Hardy, A..

5 recordsLinked to original sources

bioRxiv2021

Identification of DAXX As A Restriction Factor Of SARS-CoV-2 Through A CRISPR/Cas9 Screen

Interferon restricts SARS-CoV-2 replication in cell culture, but only a handful of Interferon Stimulated Genes with antiviral activity against SARS-CoV-2 have been identified. Here, we describe a functional CRISPR/Cas9 screen aiming at identifying SARS-CoV-2 restriction factors. We identified DAXX, a scaffold protein residing in PML nuclear bodies known to limit the replication of DNA viruses and retroviruses, as a potent inhibitor of SARS-CoV-2 and SARS-CoV replication in human cells. Basal expression of DAXX was sufficient to limit the replication of SARS-CoV-2, and DAXX over-expression further restricted infection. In contrast with most of its previously described antiviral activities, DAXX-mediated restriction of SARS-CoV-2 was independent of the SUMOylation pathway. SARS-CoV-2 infection triggered the re-localization of DAXX to cytoplasmic sites and promoted its degradation. Mechanistically, this process was mediated by the viral papain-like protease (PLpro) and the proteasome. Together, these results demonstrate that DAXX restricts SARS-CoV-2, which in turn has evolved a mechanism to counteract its action.

microbiology↗

bioRxiv2021

Aminoglycoside antibiotics inhibit phage infection by blocking an early step of the phage infection cycle

In response to viral predation, bacteria have evolved a wide range of defense mechanisms, which rely mostly on proteins acting at the cellular level. Here, we show that aminoglycosides, a well-known class of antibiotics produced by Streptomyces, are potent inhibitors of phage infection in widely divergent bacterial hosts. We demonstrate that aminoglycosides block an early step of the viral life cycle, prior to genome replication. Phage inhibition was also achieved using supernatants from natural aminoglycoside producers, hinting at a broad physiological significance of the antiviral properties of aminoglycosides. Strikingly, we show that acetylation of the aminoglycoside antibiotic apramycin abolishes its antibacterial effect, but retains its antiviral properties. Altogether, this study expands the knowledge of potential aminoglycoside functions in bacterial communities suggesting that aminoglycosides are not only used by their producers as toxic molecules against their bacterial competitors, but could also provide protection against the threat of phage predation at the community level.

microbiology↗

bioRxiv2021

Multilamellar mesoporous silica nanoparticles using a cationic co-surfactant dual-templating method.

The utility of mesoporous silica nanoparticles (MSNs) has been repeatedly proven in a wide range of biomedical applications. The general morphology of these particles is easily modifiable by various post-grafting possibilities and adjustments within the surfactant-based template. The synthesis of multilamellar vesicular silica nanoparticles has led to the discovery of beneficial attributes regarding said particles. Depending on the synthesis process, various parameters are affected including packaging capacity, stability, drug adsorption and release. This research focused on synthesis and characterization of multilamellar MSNs using a cationic-cationic co-surfactant templating route testing various ratios of cetyltrimethylammonium bromide (CTAB) and didodecyldimethylammonium bromide (DDAB). TEM imaging showed clear differences in size and morphology between the different samples, and was further characterized by BET and BJH analysis. All multilamellar nanoparticles did exhibit a similar pore size distribution and overall gradual release of drug contents. However, the degree of drug adsorption and overtime drug release was clearly influenced by the number of layers of the MSNs, proving the utility of adjusting the template. Further experiments could be conducted to validate the utility of beta-cyclodextrin as a template regulator and to investigate both biocompatibility and biodegradability of the multilamellar MSNs.

bioengineering↗

bioRxiv2021

Genome sequencing of the bacteriophage CL31 and interaction with the host strain Corynebacterium glutamicum ATCC 13032

In this study, we provide a comprehensive analysis of the genomic features of the phage CL31 and the infection dynamics with the biotechnologically relevant host strain Corynebacterium glutamicum ATCC 13032. Genome sequencing and annotation of CL31 revealed a 45-kbp genome composed of 72 open reading frames, mimicking the GC content of its host strain (54.4 %). An ANI-based distance matrix showed the highest similarity of CL31 to the temperate corynephage {Phi}16. While the C. glutamicum ATCC 13032 wild type strain showed only mild propagation of CL31, a strain lacking the cglIR-cglIIR-cglIM restriction-modification system was efficiently infected by this phage. Interestingly, the prophage-free strain C. glutamicum MB001 featured an even accelerated amplification of CL31 compared to the {Delta}resmod strain suggesting a role of cryptic prophage elements in phage defense. Proteome analysis of purified phage particles and transcriptome analysis provide important insights into structural components of the phage and the response of C. glutamicum to CL31 infection. Isolation and sequencing of CL31-resistant strains revealed SNPs in genes involved in mycolic acid biosynthesis suggesting a role of this cell envelope component in phage adsorption. Altogether, these results provide an important basis for further investigation of phage-host interactions in this important biotechnological model organism.

microbiology↗

bioRxiv2020

Genome sequence and characterization of five bacteriophages infecting Streptomyces coelicolor and Streptomyces venezuelae: Alderaan, Coruscant, Dagobah, Endor1 and Endor2

Streptomyces are well-known antibiotic producers, and are also characterized by a complex morphological differentiation. Streptomyces, like all bacteria, are confronted with the constant threat of phage predation, which in turn shapes bacterial evolution. However, despite significant sequencing efforts recently, relatively few phages infecting Streptomyces have been characterized compared to other genera. Here, we present the isolation and characterization of five novel Streptomyces phages. All five phages belong to the Siphoviridae family, based on their morphology as determined by transmission electron microscopy. Genome sequencing revealed that four of them were temperate phages, while one had a lytic lifestyle. Moreover, one of the newly sequenced phages shows very little homology to already described phages, highlighting the still largely untapped viral diversity. Altogether, this study expands the number of characterized phages of Streptomyces and sheds light on phage evolution and phage-host dynamics in Streptomyces.

microbiology↗