Biology subjects

Faurdal, D.

Publications and source records attributed to Faurdal, D..

3 recordsLinked to original sources

bioRxiv2025

Tying up loose ends: Recovering thousands of missing telomeres from Streptomyces and other Streptomycetaceae genomes

Members of the Gram-positive Streptomycetaceae family of bacteria have linear chromosomes and carry linear plasmids, which end in telomeres bound by proteins. In a large-scale analysis of 762 linear complete genomes, we discovered that the telomeres were truncated in most assemblies, as they are not captured by Oxford Nanopore sequencing. To address this issue, we present Telomore, a tool to reconstitute this missing telomeric sequence using ONT and Illumina data. In the studied dataset, Telomore increased detection of archetypal telomeres from 0% to 37%, which could be near the occurrence rate in nature. Combining these reconstituted telomeres with previously published telomeres and all complete Streptomycetaceae RefSeq genomes, we created a compendium of more than 2000 telomeres. Similarity-based clustering identified 137 telomere clusters. We find that 78% of Telomore-extended chromosomes encode both telomeres, while this is only the case for 15% of comparable RefSeq chromosomes. Therefore, most assignments of "complete" to Streptomycetaceae are erroneous. Finally, we mined the 762 genomes for known telomeric maintenance proteins and used those to identify a plasmid-specific archetypal telomere and to identify a previously unidentified protein family likely involved with the maintenance of Sg2247-class telomeres. Together, these results highlight a common issue assembling complete linear Streptomycetaceae genomes and provide a programmatic solution and identify a candidate for a new telomeric protein. VISUAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=78 SRC="FIGDIR/small/682034v1_ufig1.gif" ALT="Figure 1"> View larger version (13K): org.highwire.dtl.DTLVardef@1adbb96org.highwire.dtl.DTLVardef@f68519org.highwire.dtl.DTLVardef@9c50b4org.highwire.dtl.DTLVardef@768c00_HPS_FORMAT_FIGEXP M_FIG C_FIG

microbiology↗

bioRxiv2024

A treasure trove of 1,034 actinomycete genomes

Filamentous Actinobacteria, recently renamed Actinomycetia, are the most prolific source of microbial bioactive natural products. Studies on biosynthetic gene clusters benefit from or require chromosome-level assemblies. Here, we provide DNA sequences from more than 1,000 isolates: 881 complete genomes and 153 near-complete genomes, representing 28 genera and 389 species, including 244 likely novel species. All genomes are from filamentous isolates of the class Actinomycetia from the NBC culture collection. The largest genus is Streptomyces with 886 genomes including 742 complete assemblies. We use this data to show that analysis of complete genomes can bring biological understanding not previously derived from more fragmented sequences or less systematic datasets. We document the central and structured location of core genes and distal location of specialized metabolite biosynthetic gene clusters and duplicate core genes on the linear Streptomyces chromosome, and analyze the content and length of the terminal inverted repeats which are characteristic for Streptomyces. We then analyze the diversity of trans-AT polyketide synthase biosynthetic gene clusters, which encodes the machinery of a biotechnologically highly interesting compound class. These insights have both ecological and biotechnological implications in understanding the importance of high quality genomic resources and the complex role synteny plays in Actinomycetia biology.

microbiology↗

bioRxiv2023

CASCADE-Cas3 Enables Highly Efficient Genome Engineering in Streptomyces Species

Type I CRISPR systems are widespread in bacteria and archaea. The main differences compared to more widely applied type II systems are multi-effector CASCADE needed for crRNA processing and target recognition, as well as the processive nature of the hallmark nuclease Cas3. Given the widespread nature of type I systems, the processive nature of Cas3, as well as the recombinogenic overhangs created by Cas3, we hypothesized that Cas3 would be uniquely positioned to enable efficient genome engineering in streptomycetes. Here, we report a new type I based CRISPR genome engineering tool for streptomycetes. The plasmid system, called pCRISPR-Cas3, utilizes a compact type I-C CRISPR system and enables highly efficient genome engineering. pCRISPR-Cas3, outperforms pCRISPR-Cas9 and facilitates targeted and random sized deletions, as well as substitutions of large genomic regions such as biosynthetic gene clusters. Without additional modifications, pCRISPR-Cas3 enabled genome engineering in several Streptomyces species at high efficiencies.

synthetic biology↗