A Structural Study on the Listeria Monocytogenes Internalin A—Human E-cadherin Interaction: A Molecular Tool to Investigate the Effects of Missense Mutations

Abstract

Listeria monocytogenes is a widespread foodborne pathogen of high concern and internalin A is an important virulence factor that mediates cell invasion upon the interaction with the host protein E-cadherin. Nonsense mutations of internalin A are known to reduce virulence. Although missense mutations are largely overlooked, they need to be investigated in respect to their effects in cell invasion processes. This work presented a computational workflow to early characterize internalin A missense mutations. The method reliably estimated the effects of a set of engineered missense mutations in terms of their effects on internalin A–E-cadherin interaction. Then, the effects of mutations of an internalin A variant from a L. monocytogenes isolate were calculated. Mutations showed impairing effects on complex stability providing a mechanistic explanation of the low cells invasion capacity previously observed. Overall, our results provided a rational approach to explain the effects of internalin A missense mutations. Moreover, our findings highlighted that the strength of interaction may not directly relate to the cell invasion capacity reflecting the non-exclusive role of internalin A in determining the virulence of L. monocytogenes. The workflow could be extended to other virulence factors providing a promising platform to support a better molecular understanding of L. monocytogenes epidemiology.

Assessment of Internalin A Gene Sequences and Cell Adhesion and Invasion Capacity of Listeria monocytogenes Strains Isolated from Foods of Animal and Related Origins

“…There are several internalins identified in the genome, being encoded by different genes, as an example inlD which is related to invasion activity (Seveau et al, 2007). Therefore, the results of this research corroborate with the literature that InlA has an important, although not exclusive, role in determining the virulence of L. monocytogenes strains (Van Stelten et al, 2016;Dellafiora et al, 2020). Among other factors related to invasion is listeriolysin O (poreforming toxin), which is known as an important cooperative determinant to increase the efficiency of host cell invasion (Phelps et al, 2018).…”

“…Thus, in this way, several virulence factors may be involved at the same stage of the cycle, with some operating at the same stage and others having a more restricted action. Dellafiora et al (2020) argue that despite the prevalence of full-length InlA sequences in clinical isolates, a growing body of evidence suggests that there is no direct correlation between the inlA sequence or InlA integrity and the ability to invade cells or cause infection. Experimental data pointed out that a strong InlA-Ecad interaction may not be essential to determine the cell invasion capacity of L. monocytogenes (Dellafiora et al, 2020).…”

“…Analyses of missense mutations, using computational models, demonstrate possible effects of its mutations on the capability to interact with Ecad and that a strong interaction between InlA and Ecad is important, but perhaps not essential in the capacity for cell invasion (Dellafiora et al, 2020). Dellafiora et al (2020) call attention to missense mutations, even though they are largely ignored; they need to be investigated in relation to their effects on cell invasion processes. The strength of the interaction may not be directly related to the capacity for cellular invasion, reflecting the nonexclusive role of inlA in determining the virulence of L. monocytogenes (Dellafiora et al, 2020).…”

“…Dellafiora et al (2020) call attention to missense mutations, even though they are largely ignored; they need to be investigated in relation to their effects on cell invasion processes. The strength of the interaction may not be directly related to the capacity for cellular invasion, reflecting the nonexclusive role of inlA in determining the virulence of L. monocytogenes (Dellafiora et al, 2020).…”

The Compromised Intestinal Barrier Induced by Mycotoxins

“…In vivo studies, based on information from whole-animal systems, can effectively emulate the toxicity mechanisms in humans. The role of live animals for education and research purposes has been recognized by the World Organisation for Animal Health (OIE) [ 73 ]. In general, several animal species, such as mice, rats, chickens, turkey, fish, pigs, sheep, and cows, have been used to evaluate the toxicology of mycotoxins.…”