Characterization of the pgf operon involved in the posttranslational modification of Streptococcus mutans surface proteins.

Protein glycosylation has been described as the most abundant and complex post-translational modification occurring in nature. Recent studies have enhanced our view of how this modification occurs in bacteria highlighting the role of protein glycosylation in various processes such as biofilm formation, virulence and host-microbe interactions. We recently showed that the collagen- and laminin-binding adhesin Cnm of the dental pathogen Streptococcus mutans is post-translationally modified by the PgfS glycosyltransferase.

K+ modulates genetic competence and the stress regulon of Streptococcus mutans.

Potassium (K+) is the most abundant cation in dental plaque fluid. Previously, we reported the link between K+ transport via Trk2 in Streptococcus mutans and its two critical virulence attributes: acid tolerance and surface adhesion. Herein, we build further on the intimate link between K+ levels and S.

Functional amyloids in Streptococcus mutans, their use as targets of biofilm inhibition and initial characterization of SMU_63c.

Amyloids have been identified as functional components of the extracellular matrix of bacterial biofilms. Streptococcus mutans is an established aetiologic agent of dental caries and a biofilm dweller. In addition to the previously identified amyloidogenic adhesin P1 (also known as AgI/II, PAc), we show that the naturally occurring antigen A derivative of S.

Extracellular protease digestion to evaluate membrane protein cell surface localization.

Membrane proteins have crucial roles in signaling and as anchors for cell surface display. Proper secretion of a membrane protein can be evaluated by its susceptibility to digestion by an extracellular protease, but this requires a crucial control to confirm membrane integrity during digestion. This protocol describes how to use this approach to determine how efficiently a protein is secreted to the outer surface of Gram-negative bacteria.

Identification of a supramolecular functional architecture of Streptococcus mutans adhesin P1 on the bacterial cell surface.

P1 (antigen I/II) is a sucrose-independent adhesin of Streptococcus mutans whose functional architecture on the cell surface is not fully understood. S. mutans cells subjected to mechanical extraction were significantly diminished in adherence to immobilized salivary agglutinin but remained immunoreactive and were readily aggregated by fluid-phase salivary agglutinin.

Association of cytokine and Toll-like receptor gene polymorphisms with severe malaria in three regions of Cameroon.

P. falciparum malaria is one of the most widespread and deadliest infectious diseases in children under five years in endemic areas. The disease has been a strong force for evolutionary selection in the human genome, and uncovering the critical human genetic factors that confer resistance to the disease would provide clues to the molecular basis of protective immunity that would be invaluable for vaccine development.

An alternative outer membrane secretion mechanism for an autotransporter protein lacking a C-terminal stable core.

Autotransporter (AT) proteins are a broad class of virulence factors from Gram-negative pathogens. AT outer membrane (OM) secretion appears simple in many regards, yet the mechanism that enables transport of the central AT 'passenger' across the OM remains unclear. OM secretion efficiency for two AT passengers is enhanced by approximately 20 kDa stable core at the C-terminus of the passenger, but studies on a broader range of AT proteins are needed in order to determine whether a stability difference between the passenger N- and C-terminus represents a truly common mechanistic feature.

ATP-independent control of autotransporter virulence protein transport via the folding properties of the secreted protein.

Autotransporter (AT) proteins are the largest class of extracellular virulence proteins secreted from Gram-negative bacteria. The mechanism by which AT proteins cross the bacterial outer membrane (OM), in the absence of ATP or another external energy source, is unknown. Here we demonstrate a linear correlation between localized regions of stability (ΔG(folding)) in the mature virulence protein (the AT "passenger") and OM secretion efficiency.

Vectorial transport and folding of an autotransporter virulence protein during outer membrane secretion.

Autotransporter (AT) proteins are a large and diverse family of extracellular virulence proteins from Gram-negative bacteria, characterized by a central beta-helix domain within the mature virulence protein. It is not clear how these proteins cross the outer membrane (OM) quickly and efficiently, without assistance from an external energy source such as ATP or a proton gradient. Conflicting results in the literature have led to several proposed mechanisms for AT OM secretion, including a concerted process, or vectorial secretion with different directionalities.