Abstract
The adhesin Legionella collagen-like (Lcl) protein can bind to extracellular matrix components and mediate the binding of Legionella pneumophila to host cells. In this study, electrochemical impedance spectroscopy (EIS) and surface plasmon resonance (SPR)-based biosensors were employed to characterize these interactions between glycosaminoglycans (GAGs) and the adhesin Lcl protein. Fucoidan displayed a high affinity (KD 18 nM) for Lcl protein. Chondroitin sulfate A and dermatan sulfate differ in the position of a carboxyl group replacing D-glucuronate with D-iduronate. Our results indicated that the presence of D-iduronate in dermatan sulfate strongly hindered its interaction with Lcl. These biophysical studies provided valuable information in our understanding of adhesin-ligand interactions related to Legionella pneumophila infections.
Highlights
Legionella pneumophila is a Gram-negative, facultative intracellular pathogen and the causative agent of Legionnaire’s disease
His-tagged Legionella collagen-like (Lcl) proteins were attached to the Ni-NTA surface (Supplementary Figure S2) on the sensor chips to allow further interactions with the analytes
As the GAGs were exposed to the surface-immobilized Lcl protein, the surface plasmon resonance (SPR) angle shifted, which, in turn, increased the response unit
Summary
Legionella pneumophila is a Gram-negative, facultative intracellular pathogen and the causative agent of Legionnaire’s disease. The latter could lead to severe pneumonia and even death, if not treated at an early stage [1,2,3]. The molecular basis of biofilm formation by L. pneumophila was reported along with the role of other microbial species in L. pneumophila biofilm colonization [6]. Bacterial aggregates of L. pneumophila have been reported to have the ability to resist various host defenses and colonize their biofilm environment efficiently [7]. Recent studies have hypothesized that Legionella collagen-like (Lcl) protein induced the auto-aggregation process in a divalent-cation-dependent manner. The isolates from Legionella species which did not produce Lcl, were deficient in auto-aggregation [7]
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