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.

Novel Aggregation Promoting Factor AggE Contributes to the Probiotic Properties of Enterococcus faecium BGGO9-28

“…A comparison of the ability of aggregation and the size of the deleted region in aggE gene/protein indicates that there is no corelation between the size of deletion and agregation, collagen, fibronectin and mucin binding ability, and biofilm formation. It seems that the structure and the presence of the respective domains, not the length of the peptide, is responsible for the expression of certain auto-aggregation phenotypes or adhesion ability, as demonstrated previously for AggLb (Miljkovic et al, 2016 ).…”

“…Aggregation and biofilm formation are multicellular processes that allow a community to be more resistant to stress conditions. Given that these are similar processes, it is not surprising that the same protein could be involved in both functions (Miljkovic et al, 2016 ). It is considered that the expressed aggE gene contributes to the increase of biofilm formation in a heterologous host, but it is not entirely (clones carrying AggE increased only about two times formation of biofim), indicated that additional factors/genes in enterococci are responsible for the full expression of this phenotype (Figure 7D ).…”

RadA, a MSCRAMM Adhesin of the Dominant Symbiote Ruminococcus gnavus E1, Binds Human Immunoglobulins and Intestinal Mucins

“…Previous works reported that the region involved in the recognition of extracellular matrix components by CNA-like adhesins is located in the N-terminal part of the protein, upstream of the repeated domains [ 29 ]. For the Cna adhesins of S. aureus and the AggLb adhesin of Lactobacillus paracasei , it was also proposed that the CnaB-domains act as a “stalk” that projects the N-terminal domain from the bacterial surface and facilitates its adherence to the matrix [ 32 , 33 ]. Similarly, we hypothesized that the 10 CnaB-like domains of RadA act as an antenna that projects the Ig-like domain and facilitates its adherence to mucus.…”

Characterization of the phosphate-specific transport system inCronobacter sakazakiiBAA-894

“…Auto‐aggregation activity was measured according to published methods (Miljkovic et al . ) with modification. Briefly, cells were grown in LP or LB broth for 3 h at 37°C, harvested by centrifugation at 12 000 g for 3 min, and then gently washed twice and resuspended in PBS.…”