Expression of Internalin a and Biofilm Formation among Listeria Monocytogenes Clinical Isolates

Abstract

Internalin A (InlA), a cell wall-bound protein of Listeria monocytogenes, is among the major components involved in the adhesion to and invasion of host cells expressing specific forms of E-cadherin. Some L. monocytogenes strains secrete truncated non-functional forms of InlA. The purpose of this study is to compare the biofilm-forming abilities of L. monocytogenes strains from clinical sources expressing InlA proteins in the different forms. A total of 70 L. monocytogenes strains were examined using SDS-PAGE, Western blot, DNA sequencing, and microtitre plate biofilm formation assays. We found that 8 of the 70 strains expressed truncated InlA, and that this group of strains exhibited significantly enhanced biofilm-forming ability compared to the group expressing full-length InlA. Further experiments showed that: (i) L. monocytogenes biofilms were detached by treatment with protease K; (ii) protein fragments resulting from proteolysis, rather than intact proteins, are responsible for biofilm enhancement, because biofilm formation was impaired by the protease inhibitor alpha2-macroglobulin; (iii) truncated and/or proteolytically cleaved InlA are likely involved in the biofilm enhancement, based on the effects that anti-InlA monoclonal antibodies produced on the biofilm formation of L. monocytogenes strains expressing either truncated or full-length InlA. These data provide a basis for further investigation of the molecular structure and composition of L. monocytogenes biofilms.

Inhibitory effects of the κ-casein macropeptide isolated from milk protein on the biofilm formation and virulence of Listeria monocytogenes

“…The biofilm-forming ability of L. monocytogenes strains has recently been reported to be significantly influenced by the modification of internalin A. 37) We have indicated here that the mRNA level of inlA in HT-29 cells was specifically repressed in the presence of 0.4 mg/mL. These findings are consistent with our results that CMP significantly inhibited the invasion of L. monocytogenes in mammalian cells (Table 2) as well as the biofilm formation (Fig.…”

Bacterial community assembly based on functional genes rather than species

“…An array of proteins functionally assigned to attachment and biofilm formation were overrepresented across U. australis samples. Functions include homologs of the OmpA protein (COG2197), which is required for adhesion to both mammalian and fish epithelial cells in a range of Proteobacteria (23,24), Listeria internalin-like proteins, which enhance attachment and biofilm formation (25,26), and the widespread colonization island, which is essential for biofilm formation, colonization, and pathogenesis in a range of bacteria (27). Proteins related to the production and excretion of galactoglycan, or exopolysaccharide II, were more abundant in the U. australis community, and apart from forming part of the biofilm matrix, is also essential for the establishment and maintenance of symbiosis in several Rhizobium strains (28)(29)(30)(31)(32).…”

Role of PBPD1 in Stimulation of Listeria monocytogenes Biofilm Formation by Subminimal Inhibitory β-Lactam Concentrations

“…S2 in the supplemental material), an interesting finding as biofilms are typically considered more tolerant of antibiotics than planktonic cells (10,68). Small molecules or fatty acids can cause dispersal of biofilms (69)(70)(71)(72), as can degradation of the EPS matrix (7,65,73). In our assays, none of the ␤-lactams tested could fully disperse established biofilms ( Fig.…”

“…Along these lines, stimulation of biofilm formation in some Staphylococcus aureus strains by sub-MIC methicillin requires expression of the AtlA autolysin, a PG hydrolase, which enhances release of eDNA (64). In addition to eDNA, L. monocytogenes EPS contains proteins (65). Protease pretreatment of L. monocytogenes reduced the levels of the surface-exposed Ami4b autolysin, resulting in decreased biofilm formation (66).…”