Biology subjects

Sockett, R. E.

Publications and source records attributed to Sockett, R. E..

4 recordsLinked to original sources

bioRxiv2026

A C-terminal Processing Protease Implicated in Flagellin Turnover and Developmental Progression in a Bacterial Predator

Carboxy-terminal processing proteases (CTPs) are widely conserved bacterial proteases implicated in protein maturation, quality control, and stress responses, yet many family members functions remain unclear. Here, we characterise Bd0967, a previously unstudied CTP from the predatory bacterium Bdellovibrio bacteriovorus, and its role in flagellar function during predatory development. Crystal structures reveal a self-compartmentalised protease in which a PDZ domain forms a lid over a large internal cavity accessed through a proteolytic tunnel. Co-purifying peptides occupied two distinct substrate-binding sites, suggesting a coordinated recognition mechanism. Affinity pulldowns coupled with mass spectrometry identified several Bdellovibrio flagellins as candidate substrates, which were subsequently validated by biochemical assays and shown to be selectively degraded through recognition of a conserved C-terminal motif. A Bd0967-mCherry translational fusion localised to periplasmic foci during the intracellular predatory growth, consistent with flagellar resorption and flagellin turnover following prey invasion. Deletion of bd0967 caused developmental defects, including aberrant Bdellovibrio cell morphology and reduced predation efficiency. Together, these findings establish Bd0967 as a specialised CTP that couples flagellin degradation and developmental progression in a predatory bacterium.

biochemistry↗

bioRxiv2023

Histone-organized chromatin in bacteria

Histones are the principal constituents of chromatin in eukaryotes and most archaea, while bacteria generally rely on an orthogonal set of proteins to organize their chromosomes. However, several bacterial genomes encode proteins with putative histone fold domains. Whether these proteins are structurally and functionally equivalent to archaeal and eukaryotic histones is unknown. Here, we demonstrate that histones are essential and are major components of chromatin in the bacteria Bdellovibrio bacteriovorus and Leptospira interrogans. Patterns of sequence evolution suggest important roles in several additional bacterial clades. Structural analysis of the B. bacteriovorus histone (Bd0055) dimer shows that histone fold topology is conserved between bacteria, archaea, and eukaryotes. Yet, unexpectedly, Bd0055 binds DNA end-on and forms a sheath of tightly packed histone dimers to encase straight DNA. This binding mode is in stark contrast to archaeal, eukaryotic, and viral histones, which invariably bend and wrap DNA around their outer surface. Our results demonstrate that histones are integral chromatin components across the tree of life and highlight organizational innovation in the domain Bacteria.

molecular biology↗

bioRxiv2021

Asymmetric peptidoglycan editing generates the curvature of predatory bacteria, optimizing invasion and replication within a spherical prey niche

The vibrioid predatory bacterium Bdellovibrio bacteriovorus secretes prey wall-modifying enzymes to invade and replicate within the periplasm of Gram-negative prey bacteria. Studying self-modification of predator wall peptidoglycan during predation, we discover that Bd1075 generates self-wall curvature by exerting LD-carboxypeptidase activity in the vibrioid B. bacteriovorus strain HD100 as it grows inside spherical prey. Bd1075 localizes to the outer curved face of B. bacteriovorus, in contrast to most known shape-determinants. Asymmetric protein localization is determined by the novel function of a nuclear transport factor 2-like (NTF2) domain at the protein C-terminus. The solved structure of Bd1075 is monomeric, with key differences to other LD-carboxypeptidases. Rod-shaped {Delta}bd1075 mutants invade prey more slowly than curved wild-type predators, and stretch and deform the invaded prey cell from within. Vibrioid morphology increases the evolutionary fitness of wild predatory bacteria, facilitating efficient prey invasion and intracellular growth of curved predators inside a spherical prey niche.

microbiology↗

bioRxiv2019

Dynamics of chromosome replication and its relationship to predatory attack lifestyles in Bdellovibrio bacteriovorus

Bdellovibrio bacteriovorus is a small Gram-negative, an obligate predatory bacterium that is largely found in wet, aerobic environments (i.e. soil). This bacterium attacks and invades other Gram-negative bacteria, including animal and plant pathogens. The intriguing life cycle of B. bacteriovorus consists of two phases: a free-living non-replicative attack phase wherein the predatory bacterium searches for its prey, and a reproductive phase, in which B. bacteriovorus degrades a hosts macromolecules and reuses them for its own growth and chromosome replication. Although the cell biology of this predatory bacterium has gained considerable interest in recent years, we know almost nothing about the dynamics of chromosome replication in B. bacteriovorus. Here, we performed a real-time investigation into the subcellular localization of the replisome(s) in single cells of B. bacteriovorus. Our results confirm that in B. bacteriovorus chromosome replication fires only during the reproductive phase, and show for the first time that this predatory bacterium exhibits a novel spatiotemporal arrangement of chromosome replication. The replication process starts at the invasive pole of the predatory bacterium inside the prey cell and proceeds until several copies of the chromosome have been completely synthesized. This chromosome replication is not coincident with the predator-cell division, and it terminates shortly before synchronous predator-filament septation occurs. In addition, we demonstrate that if this lifecycle fails in some cells of B. bacteriovorus, they can instead use two prey cells sequentially to complete their life cycle.\n\nImportanceNew strategies are needed to combat multidrug-resistant bacterial infections. Application of the predatory bacterium, Bdellovibrio bacteriovorus, which kills other bacteria including pathogens, is considered promising for bacterial infections. The B. bacteriovorus life cycle consists of two phases, a free-living, invasive attack phase and an intracellular reproductive phase, in which this predatory bacterium degrades the hosts macromolecules and reuses them for its own growth. To understand the use of B. bacteriovorus as a living antibiotic, it is first necessary to dissect its life cycle including chromosome replication. Here, we present for the first time a real-time investigation into subcellular localization of chromosome replication in a single cells of B. bacteriovorus. This process initiates at the invasion pole of B. bacteriovorus and proceeds until several copies of the chromosome have been completely synthesized. Interestingly, we demonstrate that some cells of B. bacteriovorus require two prey cells sequentially to complete their life cycle.

microbiology↗