Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.2.1.17 (lysozyme)
 21,489 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Acquisition of mutans streptococci at an early age is a risk factor for later caries development. Following our recent finding that human milk may inhibit adhesion of Streptococcus mutans the aim of the present study was to identify compounds in human milk preventing adhesion of mutans streptococci to saliva- or gp340-coated hydroxyapatite (s-HA and gp340-HA) using an in vitro model system. Superdex 200 fractions of human milk and purified proteins were screened for binding inhibition of the S. mutans strain Ingbritt. Avid inhibition was seen to both s-HA and gp340-HA for caseins, lactoferrin, IgA and IgG, and moderate inhibition for alpha-lactalbumin and bile salt-stimulated lipase, whereas albumin and lysozyme had no effect. The inhibitory epitope in beta-casein was delineated to its C-terminal LLNQELLNPTHQIYPVTQPLAPVHNPISV stretch by use of synthetic peptides. Similarly, a peptide (SCKFDEYFSQSCA) corresponding to the human lactoferrin stretch that is highly homologous to the previously shown inhibitory stretch of bovine lactoferrin was found to inhibit S. mutans Ingbritt binding. Inhibition by human milk, IgA, and the inhibitory beta-casein peptide was universal among 4 strains of S. mutans (Ingbritt, NG8, LT11, JBP) and 2 strains of S. sobrinus (6715 and OMZ176). IgG inhibited 4, alpha-lactalbumin 3 and lactoferrin 2 of these 6 strains. It was also confirmed that none of the milk components coated on HA mediated S. mutans Ingbritt adhesion, which was consistent with the finding that no milk protein was recognized on Western blots by gp340/DMBT1 monoclonal antibodies.
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PMID:Human milk compounds inhibiting adhesion of mutans streptococci to host ligand-coated hydroxyapatite in vitro. 1939 Jan 91

It is generally thought that mucosal fluids protect underlying epithelial surfaces against opportunistic infection via their antimicrobial activity. However, our published data show that human tear fluid can protect against the major opportunistic pathogen Pseudomonas aeruginosa independently of bacteriostatic activity. Here, we explored the mechanisms for tear protection, focusing on impacts of tear fluid on bacterial virulence factor expression. Results showed that tear fluid suppressed twitching motility, a type of surface-associated movement conferred by pili. Previously, we showed that twitching is critical for P. aeruginosa traversal of corneal epithelia, exit from epithelial cells after internalization, and corneal virulence. Inhibition of twitching by tear fluid was dose-dependent with dilutions to 6.25% retaining activity. Purified lactoferrin, lysozyme, and contrived tears containing these, and many other, tear components lacked the activity. Systematic protein fractionation, mass spectrometry, and immunoprecipitation identified the glycoprotein DMBT1 (Deleted in Malignant Brain Tumors 1) in tear fluid as required. DMBT1 purified from human saliva also inhibited twitching, as well as P. aeruginosa traversal of human corneal epithelial cells in vitro, and reduced disease pathology in a murine model of corneal infection. DMBT1 did not affect PilA expression, nor bacterial intracellular cyclicAMP levels, and suppressed twitching motility of P. aeruginosa chemotaxis mutants (chpB, pilK), and an adenylate cyclase mutant (cyaB). However, dot-immunoblot assays showed purified DMBT1 binding of pili extracted from PAO1 suggesting that twitching inhibition may involve a direct interaction with pili. The latter could affect extension or retraction of pili, their interactions with biotic or abiotic surfaces, or cause their aggregation. Together, the data suggest that DMBT1 inhibition of twitching motility contributes to the mechanisms by which mucosal fluids protect against P. aeruginosa infection. This study also advances our understanding of how mucosal fluids protect against infection, and suggests directions for novel biocompatible strategies to protect our surface epithelia against a major opportunistic pathogen.
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PMID:Mucosal fluid glycoprotein DMBT1 suppresses twitching motility and virulence of the opportunistic pathogen Pseudomonas aeruginosa. 2889 91