LAP, an alcohol acetaldehyde dehydrogenase enzyme in Listeria, promotes bacterial adhesion to enterocyte-like Caco-2 cells only in pathogenic species

Abstract

Listeria adhesion protein (LAP), an alcohol acetaldehyde dehydrogenase (lmo1634), interacts with host-cell receptor Hsp60 to promote bacterial adhesion during the intestinal phase of Listeria monocytogenes infection. The LAP homologue is present in pathogens (L. monocytogenes, L. ivanovii) and non-pathogens (L. innocua, L. welshimeri, L. seeligeri); however, its role in nonpathogens is unknown. Sequence analysis revealed 98 % amino acid similarity in LAP from all Listeria species. The N-terminus contains acetaldehyde dehydrogenase (ALDH) and the Cterminus an alcohol dehydrogenase (ADH). Recombinant LAP from L. monocytogenes, L. ivanovii, L. innocua and L. welshimeri exhibited ALDH and ADH activities, and displayed strong binding affinity (K D 2-31 nM) towards Hsp60. Flow cytometry, ELISA and immunoelectron microscopy revealed more surface-associated LAP in pathogens than non-pathogens. Pathogens exhibited significantly higher adhesion (P,0.05) to Caco-2 cells than non-pathogens; however, pretreatment of bacteria with Hsp60 caused 47-92 % reduction in adhesion only in pathogens. These data suggest that biochemical properties of LAP from pathogenic Listeria are similar to those of the protein from non-pathogens in many respects, such as substrate specificity, immunogenicity, and binding affinity to Hsp60. However, protein fractionation analysis of extracts from pathogenic and non-pathogenic Listeria species revealed that LAP was greatly reduced in intracellular and cell-surface protein fractions, and undetectable in the extracellular milieu of nonpathogens even though the lap transcript levels were similar for both. Furthermore, a LAP preparation from L. monocytogenes restored adhesion in a lap mutant (KB208) of L. monocytogenes but not in L. innocua, indicating possible lack of surface reassociation of LAP molecules in this bacterium. Taken together, these data suggest that LAP expression level, cellsurface localization, secretion and reassociation are responsible for LAP-mediated pathogenicity and possibly evolved to adapt to a parasitic life cycle in the host.

Mucosal Antibodies to the C Terminus of Toxin A Prevent Colonization of Clostridium difficile

“…The two dehydrogenases recognized by TcdA 26 -39 -specific antibodies, AdhE1 and LdhA, could also have potential roles in virulence. In Listeria monocytogenes, an aldehyde alcohol dehydrogenase is a housekeeping enzyme but is also a surface-exposed adhesin commonly referred to as LAP (Listeria adhesion protein) (33). In C. difficile, LdhA participates in a biosynthetic pathway, another member of which, HadA, has been found to be associated with biofilms, a key attribute linked to colonization (34).…”

The arsenal of virulence factors deployed byListeria monocytogenesto promote its cell infection cycle

“…The interaction of this alcohol acetaldehyde dehydrogenase with Hsp60, its host cell receptor, promotes bacterial adhesion to intestinal cells. [29][30][31][32] Anaerobic growth induces significant increases in the level of lap transcript and Lap secretion via the accessory secretion system SecA2 (see regulation section). Oral administration of lap-deficient strains to mice confirmed that Lap is essential for full virulence.…”

Listeria monocytogenes Uses Listeria Adhesion Protein (LAP) To Promote Bacterial Transepithelial Translocation and Induces Expression of LAP Receptor Hsp60

“…Our lab has identified Listeria adhesion protein (LAP), a 104-kDa alcohol acetaldehyde dehydrogenase (lmo1634), as a putative adhesion factor which promotes binding to cell lines of intestinal origin (29,31,32,46) and promotes translocation to the liver and spleen following oral infection of mice (6,31). LAP is present on the bacterial cell wall and is secreted by the SecA2 system (6).…”