Adaptive remodeling of the bacterial proteome by specific ribosomal modification regulates Pseudomonas infection and niche colonisation

Post-transcriptional control of protein abundance is a highly important, underexplored regulatory process by which organisms respond to their environments. Here we describe an important and previously unidentified regulatory pathway involving the ribosomal modification protein RimK, its regulator proteins RimA and RimB, and the widespread bacterial second messenger cyclic-di-GMP (cdG). Disruption of rimK affects motility and surface attachment in pathogenic and commensal Pseudomonas species, with rimK deletion significantly compromising rhizosphere colonisation by the commensal soil bacterium P. fluorescens, and plant infection by the pathogens P. syringae and P. aeruginosa. RimK functions as an ATP-dependent glutamyl ligase, adding glutamate residues to the C-terminus of ribosomal protein RpsF and inducing specific effects on both ribosome protein complement and function. Deletion of rimK in P. fluorescens leads to markedly reduced levels of multiple ribosomal proteins, and also of the key translational regulator Hfq. In turn, reduced Hfq levels induce specific downstream proteomic changes, with significant increases in multiple ABC transporters, stress response proteins and non-ribosomal peptide synthetases seen for both ΔrimK and Δhfq mutants. The activity of RimK is itself controlled by interactions with RimA, RimB and cdG. We propose that control of RimK activity represents a novel regulatory mechanism that dynamically influences interactions between bacteria and their hosts; translating environmental pressures into dynamic ribosomal changes, and consequently to an adaptive remodeling of the bacterial proteome

A Communal Bacterial Adhesin Anchors Biofilm and Bystander Cells to Surfaces

While the exopolysaccharide component of the biofilm matrix has been intensively studied, much less is known about matrix-associated proteins. To better understand the role of these proteins, we undertook a proteomic analysis of the V. cholerae biofilm matrix. Here we show that the two matrix-associated proteins, Bap1 and RbmA, perform distinct roles in the biofilm matrix. RbmA strengthens intercellular attachments. In contrast, Bap1 is concentrated on surfaces where it serves to anchor the biofilm and recruit cells not yet committed to the sessile lifestyle. This is the first example of a biofilm-derived, communally synthesized conditioning film that stabilizes the association of multilayer biofilms with a surface and facilitates recruitment of planktonic bystanders to the substratum. These studies define a novel paradigm for spatial and functional differentiation of proteins in the biofilm matrix and provide evidence for bacterial cooperation in maintenance and expansion of the multilayer biofilm

FHA-Mediated Cell-Substrate and Cell-Cell Adhesions Are Critical for Bordetella pertussis Biofilm Formation on Abiotic Surfaces and in the Mouse Nose and the Trachea

Bordetella spp. form biofilms in the mouse nasopharynx, thereby providing a potential mechanism for establishing chronic infections in humans and animals. Filamentous hemagglutinin (FHA) is a major virulence factor of B. pertussis, the causative agent of the highly transmissible and infectious disease, pertussis. In this study, we dissected the role of FHA in the distinct biofilm developmental stages of B. pertussis on abiotic substrates and in the respiratory tract by employing a murine model of respiratory biofilms. Our results show that the lack of FHA reduced attachment and decreased accumulation of biofilm biomass on artificial surfaces. FHA contributes to biofilm development by promoting the formation of microcolonies. Absence of FHA from B. pertussis or antibody-mediated blockade of surface-associated FHA impaired the attachment of bacteria to the biofilm community. Exogenous addition of FHA resulted in a dose-dependent inhibitory effect on bacterial association with the biofilms. Furthermore, we show that FHA is important for the structural integrity of biofilms formed on the mouse nose and trachea. Together, these results strongly support the hypothesis that FHA promotes the formation and maintenance of biofilms by mediating cell-substrate and inter-bacterial adhesions. These discoveries highlight FHA as a key factor in establishing structured biofilm communities in the respiratory tract

Cyclic di-GMP-Responsive Transcriptional Reporter Bioassays in \u27Pseudomonas aeruginosa\u27

3′,5′-cyclic diguanosine monophosphate (cyclic di-GMP) is a bacterial secondary messenger molecule that regulates many important cellular activities and behaviors, such as motility and biofilm formation. While mass spectrometry protocols for quantitative analyses of intracellular cyclic di-GMP concentrations have been developed, they are time intensive, expensive, low-throughput, and incapable of directly monitoring dynamic changes in vivo. In this protocol, we provide a Pseudomonas aeruginosa-specific detailed methodology to assay the intracellular levels of cyclic di-GMP using biological reporters

Mortality in Meningococcal Disease in Belgium

A survey of children admitted with meningococcal disease to 53 paediatric units in Belgium between 1975 and 1979 was made in order to assess the case mortality rate (CMR) and to identify risk factors associated with death. A total of 309 cases (226 bacteriologically confirmed and 83 unconfirmed) was recorded. The overall CMR was 6·1 per cent. It was 4·4 for bacteriologically confirmed cases and 10·8 for unconfirmed cases. The CMR was higher for septicaemia without meningitis (22·2 per cent) than for meningitis with or without signs of septicaemia (3·4 per cent). The risk of death was not related to the sex or nationality of the patients. Age was a major determinant of the CMR, independently of the clinical picture. The highest risk of death was in children under one year of age. Poor socio-economic conditions were a significant risk factor. Failure to recognise the severity of the disease by some poorly educated mothers, and the admission of the patient to a hospital lacking adequate facilities for managing severely affected children, were the two significant causes of delay of adequate treatment. © 1984 The British Society for the Study of Infection.SCOPUS: ar.jinfo:eu-repo/semantics/publishe