Disease relevance of inlB

• Differential inlA and inlB expression and interaction with human intestinal and liver cells by Listeria monocytogenes strains of different origins [1].
• Other examples for targeted proteins are the surface S-layer proteins of bacilli and clostridia, as well as virulence factors required for the pathogenesis of L. monocytogenes (internalin B) and Streptococcus pneumoniae (PspA) infections [2].
• The gene sequence encoding for the InlB protein was cloned into a Qiagen pQE-60 vector, expressed in Escherichia coli, and purified by immobilized metal affinity chromatography [3].

High impact information on inlB

• It is thought that InlB acts by binding directly to the hepatocyte growth factor (HGF) receptor, present on the surface of host cells [4].
• Analysis of a series of deletion mutants suggests that it is the B repeat region between the leucine-rich repeat and GW domains that endows InlB with an increased ability to turn on the Ras-MAP kinase pathway [4].
• Binding of InlB to the HGF receptor results in mitogen-activated protein (MAP) kinase and phosphoinositide 3-kinase activation, followed by changes in the organization of the actin cytoskeleton [4].
• This process requires the activation of phosphoinositide (PI) 3-kinase by InlB [5].
• Transfection of Hep2 cells with dominant negative Ras N17 or dominant negative Akt inhibited the induction of a reporter gene linked to the interleukin-8 promoter by InlB [5].

Biological context of inlB

• The interaction of the bacteria with different types of endothelial cells was recently analyzed, and it was shown that invasion into, but not adhesion to, human brain microvascular endothelial cells (HBMEC) depends on the product of the inlB gene, the surface molecule InlB, which is a member of the internalin multigene family [6].
• The results of this study indicate that differential expression levels of inlA and inlB possibly play a role in the virulence capacities of L. monocytogenes strains [1].
• Internalin B (InlB), a surface protein of the human pathogen Listeria monocytogenes, promotes invasion into various host cell types by inducing phagocytosis of the entire bacterium [7].
• In contrast, Internalin B, an adhesion/invasion protein from L. monocytogenes, used as a control, had binding kinetics (ka) of only 2.9 x 10(6) M(-1) s(-1) [8].

Anatomical context of inlB

• This observation led us to study the mRNA expression levels of inlA, inlB, and ami, important virulence genes mediating adhesion and invasion of eukaryotic cells, by real-time reverse transcription-PCR for 27 clinical and 37 nonclinical L. monocytogenes strains [1].

Other interactions of inlB

• Significant differences in inlA and inlB expression were observed, with clinical strains showing a lower expression level than nonclinical strains [1].
• A subsequent gel extraction and sequence typing analysis of the highly polymorphic intragenic regions in inlB and inlC simplified a previously developed multi-virulence-locus sequence typing scheme and provided discriminatory power for subtyping L. monocytogenes similar to pulsed-field gel electrophoresis analysis [9].

Analytical, diagnostic and therapeutic context of inlB

• In this study, a multiplex PCR assay was developed to allow rapid identification and easily interpretable differentiation of serotypes 1/2a and 4b from other serotypes of L. monocytogenes by simultaneously targeting two virulence genes (inlB and inlC) and two serotype-specific genes (ORF2372 and Imo0171) [9].
• Purification of the InlB fragments by immobilised metal affinity chromatography (IMAC) was optimised and confirmed by electrophoresis and Western blotting [10].
• A polyclonal antibody was produced against Internalin B (InlB)-enriched extract and used to develop an inhibition assay to detect Listeria monocytogenes cells in solution using surface plasmon resonance [3].

References