Jewett, A. I. | Search bioRxiv

bioRxiv2022

Dynamic structural adaptations enable the endobiotic predation of bdellovibrio bacteriovorus

Bdellovibrio bacteriovorus is an endobiotic microbial predator that offers promise as a living antibiotic for its ability to kill Gram-negative bacteria, including human pathogens. Even after six decades of study, fundamental details of its predation cycle remain mysterious. Here, we used cryo-electron tomography to comprehensively image the lifecycle of B. bacteriovorus at nanometer-scale resolution. In addition to providing the first high-resolution images of predation in a native (hydrated, unstained) state, we also discover several surprising features of the process, including novel macromolecular complexes involved in prey attachment/invasion and a flexible portal structure lining a hole in the prey peptidoglycan that tightly seals the prey outer membrane around the predator during entry. Unexpectedly, we find that B. bacteriovorus does not shed its flagellum during invasion, but rather resorbs it into its periplasm for degradation. Finally, following replication and division in the bdelloplast, we observe a transient and extensive ribosomal lattice on the condensed B. bacteriovorus nucleoid. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=200 SRC="FIGDIR/small/496000v1_ufig1.gif" ALT="Figure 1"> View larger version (46K): org.highwire.dtl.DTLVardef@35da74org.highwire.dtl.DTLVardef@19923f1org.highwire.dtl.DTLVardef@106a616org.highwire.dtl.DTLVardef@181f2fb_HPS_FORMAT_FIGEXP M_FIG C_FIG

microbiology↗

bioRxiv2017

Uncharacterized bacterial structures revealed by electron cryotomography

SUMMARY STATEMENTHere we present a survey of previously uncharacterized structures we have observed in bacterial cells by electron cryotomography, in the hopes of spurring their identification and study.\n\nABSTRACTElectron cryotomography (ECT) can reveal the native structure and arrangement of macromolecular complexes inside intact cells. This technique has greatly advanced our understanding of the ultrastructure of bacterial cells. Rather than undifferentiated bags of enzymes, we now view bacteria as structurally complex assemblies of macromolecular machines. To date, our group has applied ECT to nearly 90 different bacterial species, collecting more than 15,000 cryotomograms. In addition to known structures, we have observed several, to our knowledge, uncharacterized features in these tomograms. Some are completely novel structures; others expand the features or species range of known structure types. Here we present a survey of these uncharacterized bacterial structures in the hopes of accelerating their identification and study, and furthering our understanding of the structural complexity of bacterial cells.

microbiology↗