Lynham, S. | bioRxiv Science

bioRxiv2021

Molecular and cellular insight into Escherichia coli SslE and its role during biofilm maturation

Escherichia coli is a Gram-negative bacterium that colonizes the human intestine and virulent strains can cause severe diarrhoeal and extraintestinal diseases. The protein SslE is secreted by a range of pathogenic and some commensal E. coli strains. It can degrade mucins in the intestine, promotes biofilm maturation and it is a major determinant of infection in virulent strains, although how it carries out these functions is not well understood. Here we examine SslE from the E. coli Waksman and H10407 strains and reveal that it has a novel and dynamic structure. In response to acidification within mature biofilms we show how SslE forms a unique functional aggregate that interacts with cellulose and regulates the distribution of exopolysaccharides in macrocolony biofilms. Our data indicates that the spatial organization of SslE polymers and local pH are critical for biofilm maturation and SslE is a key factor that drives persistence of SslE-secreting bacteria during acidic stress.

microbiology↗

bioRxiv2020

Identification of Chlorophyll a-b Binding Protein AB96 as a novel TGFbeta1 binding agent.

The discovery of compounds and proteins from plants has greatly contributed to modern medicine, especially in malaria where both quinine and artemisinin have been the cornerstone of therapeutics. Here we describe the first known plant-derived cytokine binding agent. Chlorophyll a-b binding protein AB96, present to varying levels in the leaves of all chlorophyll-containing plants, binds to active TGF{beta}1. Active TGF{beta}1 contributes to the pathology of many infectious and neoplastic diseases and therefore, by inhibiting these processes, chlorophyll a-b binding protein opens up new approaches with therapeutic potential.

immunology↗

bioRxiv2020

Agonists of orally expressed TRP channels stimulate salivary secretion and modify the salivary proteome

Natural compounds that can stimulate salivary secretion are of interest in developing treatments for xerostomia, the perception of a dry mouth, that affects between 10 and 30% of the adult and elderly population. Chemesthetic transient receptor potential (TRP) channels are expressed in the surface of the oral mucosa. The TRPV1 agonists capsaicin and piperine have been shown to increase salivary flow when introduced into the oral cavity but the sialogogic properties of other TRP channel agonists have not been investigated. In this study we have determined the influence of different TRP channel agonists on the flow and protein composition of saliva.Mouth rinsing with the TRPV1 agonist nonivamide or menthol, a TRPM8 agonist, increased whole mouth saliva (WMS) flow and total protein secretion compared to unstimulated saliva, the vehicle control mouth rinse or cinnamaldehyde, a TRPA1 agonist. Nonivamide also increased the flow of labial minor gland saliva but parotid saliva flow rate was not increased. The influence of TRP channel agonists on the composition and function of the salivary proteome was investigated using a multi-batch quantitative mass spectrometry method novel to salivary proteomics. Inter-personal and inter-mouth rinse variation was observed in the secreted proteomes and, using a novel bioinformatics method, inter-day variation was identified with some of the mouth rinses. Significant changes in specific salivary proteins were identified after all mouth rinses. In the case of nonivamide, these changes were attributed to functional shifts in the WMS secreted, primarily the over representation of salivary and non-salivary cystatins which was confirmed by immunoassay.This study provides new evidence of the impact of TRP channel agonists on the salivary proteome and the stimulation of salivary secretion by a TRPM8 channel agonist, which suggests that TRP channel agonists are potential candidates for developing treatments for sufferers of xerostomia.AbbreviationsCARD10CAspase Recruitment Domain-containing protein 10DTTDiThioThreitolLC-MS/MSLiquid Chromatography - tandem Mass SpectrometryGOGene OntologyIEFIsoElectric FocusingLDSLithium Dodecyl SulphateMSMass SpectrometryPGPropylene GlycolPGK1PhosphoGlycerate Kinase 1TCEPTris (2-CarboxyEthyl) PhosphineTEABTriEthylAmmonium BicarbonateTMTTandem Mass TagTRPTransient Receptor PotentialTRPA1Transient Receptor Potential cation channel, subfamily A, member 1TRPM8Transient Receptor Potential cation channel subfamily M member 8TRPV1Transient Receptor Potential cation channel subfamily V member 1WMSWhole Mouth SalivaUWMSUnstimulated Whole Mouth SalivaView Full Text

physiology↗