Biology subjects

Mansky, J.

Publications and source records attributed to Mansky, J..

3 recordsLinked to original sources

bioRxiv2023

Role of XerCD in release of over-replicated DNA through Outer Membrane Vesicles in Escherichia coli

Outer membrane vesicles (OMVs) are universally produced by prokaryotes and play important roles in symbiotic and pathogenic interactions. Here we show that the Gammaproteobacterium Escherichia coli produces OMVs that contain DNA enriched for the region around the terminus of replication ter, and specifically for the recognition sequence dif of the two site-specific recombinases XerCD, similar to OMVs from the Alphaproteobacterium Dinoroseobacter shibae. In deletion mutants of xerC or xerD, the enriched region around ter becomes broader while the peak directly at the dif sequence itself is reduced. ImportanceImprecise termination of replication can lead to over-replicated parts of bacterial chromosomes that have to be excised and removed from the dividing cell. The underlying mechanism is so far poorly understood. Our data suggest a conserved mechanism for repair and removal of over-replicated DNA through outer membrane vesicles and an active role of the site-specific XerCD recombinase complex therein.

microbiology↗

bioRxiv2022

Evolution of resilience against heat stress in a red-tide dinoflagellate

"Red tides" are harmful algal blooms (HABs) caused by dinoflagellate microalgae that accumulate toxins lethal to other organisms, including humans via consumption of contaminated seafood. Increasingly frequent, HABs are driven by a combination of environmental factors including nutrient enrichment, particularly in warm waters. Here, we present the de novo assembled genome (~4.75 Gbp), transcriptome, proteome, and metabolome from Prorocentrum cordatum, a globally abundant, bloom-forming dinoflagellate. Using axenic algal cultures, we studied the molecular mechanisms that underpin response to temperature stress, which is relevant to current ocean warming trends. We discovered a complementary interplay between RNA editing and exon usage that regulates the expression and functional diversity of biomolecules, reflected by reduction in photosynthesis, central metabolism, and protein synthesis. Our multi-omics analyses uncover the molecular response to heat stress in an important HAB species, which is driven by complex gene structures in a large, high-G+C genome, combined with multi-level transcriptional regulation.

genomics↗

bioRxiv2019

Dinoroseobacter shibae outer membrane vesicles are enriched for the chromosome dimer resolution site dif

Outer membrane vesicles (OMVs) of Gram-negative bacteria have key roles in pathogenesis. However, little is known about their biogenesis and cargo in marine bacteria. In Dinoroseobacter shibae, a marine member of the Rhodobacteraceae, OMVs were produced throughout exponential growth, and DNA could be detected by fluorescence microscopy inside appr. 65% of vesicles. Single cell analysis using time-lapse microscopy showed that individual cells secreted multiple OMVs, preferentially at the septum during cell division. OMVs were enriched for saturated fatty acids, thus their secretion likely increases the fluidity of the membrane of the releasing cell locally. DNA was isolated from the vesicle lumen and sequenced; it was up to 40fold enriched for the region around the terminus of replication (ter). Within this region, the peak of coverage of vesicle DNA was located at dif, a conserved 28 bp palindromic sequence required for binding of the site specific tyrosine recombinases XerCD which are activated by the divisome protein FtsK immediately prior to septum formation. Some of the most abundant proteins of the vesicle proteome were predicted to be required for direct interaction with peptidoglycan during cell division. Single cell analysis, electron microscopy, proteome and DNA cargo show that constitutive OMV secretion in D. shibae occurs mainly prior to septum formation. The footprint of the FtsK/XerCD molecular machinery which resolves chromosome dimers suggests a novel highly conserved route for incorporation of DNA into OMVs. Clearing the division site from small DNA fragments might be an important function of this type of vesicles.

microbiology↗