title: Shortening of the Lactobacillus paracasei subsp. paracasei BGNJ1-64 AggLb Protein Switches Its Activity from Auto-aggregation to Biofilm Formation.
abstract: AggLb is the largest (318.6 kDa) aggregation-promoting protein of Lactobacillus paracasei subsp. paracasei BGNJ1-64 responsible for forming large cell aggregates, which causes auto-aggregation, collagen binding and pathogen exclusion in vitro. It contains an N-terminus leader peptide, followed by six successive collagen binding domains, 20 successive repeats (CnaB-like domains) and an LPXTG sorting signal at the C-terminus for cell wall anchoring. Experimental information about the roles of the domains of AggLb is currently unknown. To define the domain that confers cell aggregation and the key domains for interactions of specific affinity between AggLb and components of the extracellular matrix, we constructed a series of variants of the aggLb gene and expressed them in Lactococcus lactis subsp. lactis BGKP1-20 using a lactococcal promoter. All of the variants contained a leader peptide, an inter collagen binding-CnaB domain region (used to raise an anti-AggLb antibody), an anchor domain and a different number of collagen binding and CnaB-like domains. The role of the collagen binding repeats of the N-terminus in auto-aggregation and binding to collagen and fibronectin was confirmed. Deletion of the collagen binding repeats II, III, and IV resulted in a loss of the strong auto-aggregation, collagen and fibronectin binding abilities whereas the biofilm formation capability was increased. The strong auto-aggregation, collagen and fibronectin binding abilities of AggLb were negatively correlated to biofilm formation.
authors.affiliation: Laboratory for Molecular Microbiology, Institute of Molecular Genetics and Genetic Engineering, University of Belgrade Belgrade, Serbia.
authors.forename: Marija
authors.initials: M
authors.lastname: Miljkovic
authors.affiliation: Bacteriology Group, International Centre for Genetic Engineering and Biotechnology, Area Science Park Trieste, Italy.
authors.forename: Iris
authors.initials: I
authors.lastname: Bertani
authors.affiliation: Laboratory for Molecular Microbiology, Institute of Molecular Genetics and Genetic Engineering, University of BelgradeBelgrade, Serbia; Department of Biochemistry, Faculty of Biology, University of BelgradeBelgrade, Serbia.
authors.forename: Djordje
authors.initials: D
authors.lastname: Fira
authors.affiliation: Laboratory for Molecular Microbiology, Institute of Molecular Genetics and Genetic Engineering, University of BelgradeBelgrade, Serbia; Department of Biochemistry, Faculty of Biology, University of BelgradeBelgrade, Serbia.
authors.forename: Branko
authors.initials: B
authors.lastname: Jovcic
authors.affiliation: Laboratory for Molecular Microbiology, Institute of Molecular Genetics and Genetic Engineering, University of Belgrade Belgrade, Serbia.
authors.forename: Katarina
authors.initials: K
authors.lastname: Novovic
authors.affiliation: Bacteriology Group, International Centre for Genetic Engineering and Biotechnology, Area Science Park Trieste, Italy.
authors.forename: Vittorio
authors.initials: V
authors.lastname: Venturi
authors.affiliation: Laboratory for Molecular Microbiology, Institute of Molecular Genetics and Genetic Engineering, University of Belgrade Belgrade, Serbia.
authors.forename: Milan
authors.initials: M
authors.lastname: Kojic
keywords: AggLb; CnaB-like domains; auto-aggregation; biofilm formation; collagen binding domains