Lateral interactions govern self-assembly of the bacterial biofilm matrix protein BslA.

The soil bacterium is a model organism to investigate the formation of biofilms, the predominant form of microbial life. The secreted protein BslA self-assembles at the surface of the biofilm to give the biofilm its characteristic hydrophobicity. To understand the mechanism of BslA self-assembly at interfaces, here we built a molecular model based on the previous BslA crystal structure and the crystal structure of the BslA paralogue YweA that we determined.

Klebsiella pneumoniae Reduces SUMOylation To Limit Host Defense Responses.

is an important cause of multidrug-resistant infections worldwide. Understanding the virulence mechanisms of is a priority and timely to design new therapeutics. Here, we demonstrate that limits the SUMOylation of host proteins in epithelial cells and macrophages (mouse and human) to subvert cell innate immunity.

Klebsiella pneumoniae type VI secretion system-mediated microbial competition is PhoPQ controlled and reactive oxygen species dependent.

Klebsiella pneumoniae is recognized as an urgent threat to human health due to the increasing isolation of multidrug resistant strains. Hypervirulent strains are a major concern due to their ability to cause life-threating infections in healthy hosts. The type VI secretion system (T6SS) is widely implicated in microbial antagonism, and it mediates interactions with host eukaryotic cells in some cases.

Dual Predation by Bacteriophage and Can Eradicate Prey in Situations where Single Predation Cannot.

Bacteria are preyed upon by diverse microbial predators, including bacteriophage and predatory bacteria, such as While bacteriophage are used as antimicrobial therapies in Eastern Europe and are being applied for compassionate use in the United States, predatory bacteria are only just beginning to reveal their potential therapeutic uses. However, predation by either predator type can falter due to different adaptations arising in the prey bacteria. When testing poultry farm wastewater for novel isolates on prey lawns, individual composite plaques were isolated containing both an RTP (rosette-tailed-phage)-like-phage and a strain and showing central prey lysis and halos of extra lysis.

Nucleotide signaling pathway convergence in a cAMP-sensing bacterial c-di-GMP phosphodiesterase.

Bacterial usage of the cyclic dinucleotide c-di-GMP is widespread, governing the transition between motile/sessile and unicellular/multicellular behaviors. There is limited information on c-di-GMP metabolism, particularly on regulatory mechanisms governing control of EAL c-di-GMP phosphodiesterases. Herein, we provide high-resolution structures for an EAL enzyme Bd1971, from the predatory bacterium Bdellovibrio bacteriovorus, which is controlled by a second signaling nucleotide, cAMP.

Social behaviour and making attachments: a report from the fifth 'Young Microbiologists Symposium on Microbe Signalling, Organisation and Pathogenesis'.

The fifth Young Microbiologists Symposium was held in Queen's University Belfast, Northern Ireland, in late August 2018. The symposium, focused on 'Microbe signalling, organization and pathogenesis', attracted 121 microbiologists from 15 countries. The meeting allowed junior scientists to present their work to a broad audience, and was supported by the European Molecular Biology Organization, the Federation of European Microbiological Societies, the Society of Applied Microbiology, the Biochemical Society and the Microbiology Society.

Identification and Characterization of Two Klebsiella pneumoniae Lipid A Late Acyltransferases and Their Role in Virulence.

causes a wide range of infections, from urinary tract infections to pneumonia. The lipopolysaccharide is a virulence factor of this pathogen, although there are gaps in our understanding of its biosynthesis. Here we report on the characterization of , which encodes one of the enzymes responsible for the late secondary acylation of immature lipid A molecules.

Spermidine promotes biofilm formation by activating expression of the matrix regulator .

Ubiquitous polyamine spermidine is not required for normal planktonic growth of but is essential for robust biofilm formation. However, the structural features of spermidine required for biofilm formation are unknown and so are the molecular mechanisms of spermidine-stimulated biofilm development. We report here that in a spermidine-deficient mutant, the structural analogue norspermidine, but not homospermidine, restored biofilm formation.

A antibiotic resistance mechanism that subdues host defences and promotes virulence.

is an important cause of multidrug-resistant infections worldwide. Recent studies highlight the emergence of multidrug-resistant strains which show resistance to colistin, a last-line antibiotic, arising from mutational inactivation of the regulatory gene. However, the precise molecular resistance mechanisms of -associated colistin resistance and its impact on virulence remain unclear.

Giving structure to the biofilm matrix: an overview of individual strategies and emerging common themes.

Biofilms are communities of microbial cells that underpin diverse processes including sewage bioremediation, plant growth promotion, chronic infections and industrial biofouling. The cells resident in the biofilm are encased within a self-produced exopolymeric matrix that commonly comprises lipids, proteins that frequently exhibit amyloid-like properties, eDNA and exopolysaccharides. This matrix fulfils a variety of functions for the community, from providing structural rigidity and protection from the external environment to controlling gene regulation and nutrient adsorption.

Interfacial self-assembly of a bacterial hydrophobin.

The majority of bacteria in the natural environment live within the confines of a biofilm. The Gram-positive bacterium Bacillus subtilis forms biofilms that exhibit a characteristic wrinkled morphology and a highly hydrophobic surface. A critical component in generating these properties is the protein BslA, which forms a coat across the surface of the sessile community.

Biofilm formation by Bacillus subtilis: new insights into regulatory strategies and assembly mechanisms.

Biofilm formation is a social behaviour that generates favourable conditions for sustained survival in the natural environment. For the Gram-positive bacterium Bacillus subtilis the process involves the differentiation of cell fate within an isogenic population and the production of communal goods that form the biofilm matrix. Here we review recent progress in understanding the regulatory pathways that control biofilm formation and highlight developments in understanding the composition, function and structure of the biofilm matrix.

Norspermidine is not a self-produced trigger for biofilm disassembly.

Formation of Bacillus subtilis biofilms, consisting of cells encapsulated within an extracellular matrix of exopolysaccharide and protein, requires the polyamine spermidine. A recent study reported that (1) related polyamine norspermidine is synthesized by B. subtilis using the equivalent of the Vibrio cholerae biosynthetic pathway, (2) exogenous norspermidine at 25 μM prevents B.

Phosphorylated DegU manipulates cell fate differentiation in the Bacillus subtilis biofilm.

Cell differentiation is ubiquitous and facilitates division of labor and development. Bacteria are capable of multicellular behaviors that benefit the bacterial community as a whole. A striking example of bacterial differentiation occurs throughout the formation of a biofilm.

BslA is a self-assembling bacterial hydrophobin that coats the Bacillus subtilis biofilm.

Biofilms represent the predominant mode of microbial growth in the natural environment. Bacillus subtilis is a ubiquitous Gram-positive soil bacterium that functions as an effective plant growth-promoting agent. The biofilm matrix is composed of an exopolysaccharide and an amyloid fiber-forming protein, TasA, and assembles with the aid of a small secreted protein, BslA.

Genome analysis of a simultaneously predatory and prey-independent, novel Bdellovibrio bacteriovorus from the River Tiber, supports in silico predictions of both ancient and recent lateral gene transfer from diverse bacteria.

Background: Evolution equipped Bdellovibrio bacteriovorus predatory bacteria to invade other bacteria, digesting and replicating, sealed within them thus preventing nutrient-sharing with organisms in the surrounding environment. Bdellovibrio were previously described as "obligate predators" because only by mutations, often in gene bd0108, are 1 in ~1x10(7) of predatory lab strains of Bdellovibrio converted to prey-independent growth. A previous genomic analysis of B.

A small predatory core genome in the divergent marine Bacteriovorax marinus SJ and the terrestrial Bdellovibrio bacteriovorus.

Bacteriovorax marinus SJ is a predatory delta-proteobacterium isolated from a marine environment. The genome sequence of this strain provides an interesting contrast to that of the terrestrial predatory bacterium Bdellovibrio bacteriovorus HD100. Based on their predatory lifestyle, Bacteriovorax were originally designated as members of the genus Bdellovibrio but subsequently were re-assigned to a new genus and family based on genetic and phenotypic differences.

Mutagenesis of RpoE-like sigma factor genes in Bdellovibrio reveals differential control of groEL and two groES genes.

Background: Bdellovibrio bacteriovorus HD100 must regulate genes in response to a variety of environmental conditions as it enters, preys upon and leaves other bacteria, or grows axenically without prey. In addition to "housekeeping" sigma factors, its genome encodes several alternate sigma factors, including 2 Group IV-RpoE-like proteins, which may be involved in the complex regulation of its predatory lifestyle.

Results: We find that one sigma factor gene, bd3314, cannot be deleted from Bdellovibrio in either predatory or prey-independent growth states, and is therefore possibly essential, likely being an alternate sigma 70.

Discrete cyclic di-GMP-dependent control of bacterial predation versus axenic growth in Bdellovibrio bacteriovorus.

Bdellovibrio bacteriovorus is a Delta-proteobacterium that oscillates between free-living growth and predation on Gram-negative bacteria including important pathogens of man, animals and plants. After entering the prey periplasm, killing the prey and replicating inside the prey bdelloplast, several motile B. bacteriovorus progeny cells emerge.

The structure of an unconventional HD-GYP protein from Bdellovibrio reveals the roles of conserved residues in this class of cyclic-di-GMP phosphodiesterases.

Unlabelled: Cyclic-di-GMP is a near-ubiquitous bacterial second messenger that is important in localized signal transmission during the control of various processes, including virulence and switching between planktonic and biofilm-based lifestyles. Cyclic-di-GMP is synthesized by GGDEF diguanylate cyclases and hydrolyzed by EAL or HD-GYP phosphodiesterases, with each functional domain often appended to distinct sensory modules. HD-GYP domain proteins have resisted structural analysis, but here we present the first structural representative of this family (1.

The Bdellovibrio bacteriovorus twin-arginine transport system has roles in predatory and prey-independent growth.

Bdellovibrio bacteriovorus grows in one of two ways: either (i) predatorily [in a host-dependent (HD) manner], when it invades the periplasm of another Gram-negative bacterium, exporting into the prey co-ordinated waves of soluble enzymes using the prey cell contents for growth; or (ii) in a host-independent (HI) manner, when it grows (slowly) axenically in rich media. Periplasmic invasion potentially exposes B. bacteriovorus to extremes of pH and exposes the need to scavenge electron donors from prey electron transport components by synthesis of metalloenzymes.

Effects of orally administered Bdellovibrio bacteriovorus on the well-being and Salmonella colonization of young chicks.

Bdellovibrio bacteriovorus is a bacterium which preys upon and kills Gram-negative bacteria, including the zoonotic pathogens Escherichia coli and Salmonella. Bdellovibrio has potential as a biocontrol agent, but no reports of it being tested in living animals have been published, and no data on whether Bdellovibrio might spread between animals are available. In this study, we tried to fill this knowledge gap, using B.

Predatory Bdellovibrio bacteria use gliding motility to scout for prey on surfaces.

Bdellovibrio bacteriovorus is a famously fast, flagellate predatory bacterium, preying upon Gram-negative bacteria in liquids; how it interacts with prey on surfaces such as in medical biofilms is unknown. Here we report that Bdellovibrio bacteria "scout" for prey bacteria on solid surfaces, using slow gliding motility that is present in flagellum-negative and pilus-negative strains.