Biology subjects

Huennefeld, M.

Publications and source records attributed to Huennefeld, M..

4 recordsLinked to original sources

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

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↗

bioRxiv2021

Identification of Gip as a novel phage-encoded gyrase inhibitor protein featuring a broad activity profile

Bacteriophages represent a powerful source for the identification of novel antimicrobial proteins. In this study, a screening of small cytoplasmic proteins encoded by the CGP3 prophage of Corynebacterium glutamicum, resulted in the identification of the novel gyrase-inhibiting protein Cg1978 (Gip), which shows a direct interaction with the gyrase subunit A (GyrA). In vitro supercoiling assays further suggest a stabilization of the cleavage complex by Gip. Overproduction of Gip in C. glutamicum resulted in a severe growth defect as well as an induction of the SOS response. The cells adapted to gip overexpression by increasing expression levels of gyrAB and by reducing topA expression reflecting the homeostatic control of DNA topology. Interestingly, Gip features a similar activity profile towards gyrases of Escherichia coli, Mycobacterium tuberculosis and C. glutamicum. Therefore, the detailed elucidation of the mechanism of Gip action may provide novel directions for the design of drugs targeting DNA gyrase.

microbiology↗

bioRxiv2019

The MarR-type regulator MalR is involved in stress-responsive cell envelope remodeling in Corynebacterium glutamicum

1It is the enormous adaptive capacity of microorganisms, which is key to their competitive success in nature, but also challenges antibiotic treatment of human diseases. To deal with a diverse set of stresses, bacteria are able to reprogram gene expression using a wide variety of transcription factors. Here, we focused on the MarR-type regulator MalR conserved in the Corynebacterineae, including the prominent pathogens Corynebacterium diphtheriae and Mycobacterium tuberculosis. In several corynebacterial species, the malR gene forms an operon with a gene encoding a universal stress protein (uspA). Chromatin-affinity purification and sequencing (ChAP-Seq) analysis revealed that MalR binds more than 60 target promoters in the C. glutamicum genome as well as in the large cryptic prophage CGP3. Overproduction of MalR caused severe growth defects and an elongated cell morphology. ChAP-Seq data combined with a global transcriptome analysis of the malR overexpression strain emphasized a central role of MalR in cell envelope remodeling in response to environmental stresses. Prominent MalR targets are for example involved in peptidoglycan biosynthesis and synthesis of branched-chain fatty acids. Phenotypic microarrays suggest an altered sensitivity of a {Delta}malR mutant towards several {beta}-lactam antibiotics. We furthermore revealed MalR as a repressor of several prophage genes suggesting that MalR may be involved in the control of stress-responsive induction of the large CGP3 element. In conclusion, our results emphasize MalR as a regulator involved in stress-responsive remodeling of the cell envelope of C. glutamicum and suggest a link between cell envelope stress and the control of phage gene expression. ImportanceBacteria live in changing environments that force the cells to be highly adaptive. The cell envelope represents both, a barrier against harsh external conditions and an interaction interface. The dynamic remodeling of the cell envelope as a response towards, e.g. antibiotic treatment represents a major challenge in the treatment of diseases. Members of the MarR family of regulators are known to contribute to an adaptation of bacterial cells towards antibiotic stress. However, our knowledge on this adaptive response was so far restricted to a small number of well-described target genes. In this study, we performed a genome-wide profiling of DNA-binding of the MarR-type regulator MalR of C. glutamicum, which is conserved in several coryne- and mycobacterial species. By binding to more than 60 different target promoters, MalR is shaping a global reprogramming of gene expression conferring a remodeling of the cell envelope in response to stress.

microbiology↗