title: Host-derived pentapeptide affecting adhesion, proliferation, and local pH in biofilm communities composed of Streptococcus and Actinomyces species.
abstract: Salivary proline-rich proteins (PRPs) attach commensal Actinomyces and Streptococcus species to teeth. Here, gel filtration, mass spectrometry and Edman degradation were applied to show the release of a pentapeptide, RGRPQ, from PRP-1 upon proteolysis by Streptococcus gordonii. Moreover, synthetic RGRPQ and derivatives were used to investigate associated innate properties and responsible motifs. The RGRPQ peptide increased 2.5-fold the growth rate of S. gordonii via a Q-dependent sequence motif and selectively stimulated oral colonization of this organism in a rat model in vivo. In contrast, the growth of Streptococcus mutans, implicated in caries, was not affected. While the entire RGRPQ sequence was required to block sucrose-induced pH-decrease by S. gordonii and S. mutans, the N-terminal Arg residue mediated the pH increase (i.e., ammonia production) by S. gordonii alone (which exhibits Arg catabolism to ammonia). Strains of commensal viridans streptococci exhibited PRP degradation and Arg catabolism, whereas cariogenic species did not. The RGRPQ peptide mediated via a differential Q-dependent sequence motif, adhesion inhibition, and desorption of PRP-1-binding strains of A. naeslundii genospecies 2 (5 of 10 strains) but not of S. gordonii (n=5). The inhibitable A. naeslundii strains alone displayed the same binding profile as S. gordonii to hybrid peptides terminating in RGRPQ or GQSPQ, derived from the middle or C-terminal segments of PRP-1. The present findings indicate the presence of a host-bacterium interaction in which a host peptide released by bacterial proteolysis affects key properties in biofilm formation.
authors.affiliation: Department of Odontology/Cariology, Umeå University, SE-901 87 Umeå, and Division of Clinical Immunology, Karolinska University Hospital Huddinge, Stockholm, Sweden.
authors.forename: Mirva
authors.initials: M
authors.lastname: Drobni
authors.forename: Tong
authors.initials: T
authors.lastname: Li
authors.forename: Carina
authors.initials: C
authors.lastname: Krüger
authors.forename: Vuokko
authors.initials: V
authors.lastname: Loimaranta
authors.forename: Mogens
authors.initials: M
authors.lastname: Kilian
authors.forename: Lennart
authors.initials: L
authors.lastname: Hammarström
authors.forename: Hans
authors.initials: H
authors.lastname: Jörnvall
authors.forename: Tomas
authors.initials: T
authors.lastname: Bergman
authors.forename: Nicklas
authors.initials: N
authors.lastname: Strömberg
mesh_terms: D000190:Actinomyces / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D000196:Actinomycosis / Q000276:immunology; D000818:Animals; D001422:Bacterial Adhesion / Q000276:immunology / Q000502:physiology*; D018441:Biofilms / Q000254:growth & development; D049109:Cell Proliferation; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D009842:Oligopeptides / Q000502:physiology*; D010455:Peptides / Q000378:metabolism; D055232:Proline-Rich Protein Domains; D051381:Rats; D017207:Rats, Sprague-Dawley; D013290:Streptococcal Infections / Q000276:immunology; D013291:Streptococcus / Q000166:cytology / Q000378:metabolism / Q000502:physiology*
chemical_list: D009842:Oligopeptides; D010455:Peptides