Insights into the Binding Mode of Lipid A to the Anti-lipopolysaccharide Factor ALFPm3 from Penaeus monodon: An In
Cristina González-Fernández1, Christoph Öhlknecht2, Matthias Diem2
1Departamento de Ingenierías Química y Biomolecular, Universidad de Cantabria, Avda. Los Castros, s/n, 39005 Santander, Spain.
Abstract:
The globally expanding threat of antibiotic resistance calls for the development of new strategies for abating Gram-negative bacterial infections. The use of extracorporeal blood cleansing devices with affinity sorbents to selectively capture bacterial lipopolysaccharide (LPS), which is the major constituent of Gram-negative bacterial outer membranes and the responsible agent for eliciting an exacerbated innate immune response in the host during infection, has received outstanding interest. For that purpose, molecules that bind tightly to LPS are required to functionalize the affinity sorbents. Particularly, anti-LPS factors (ALFs) are promising LPS-sequestrating molecules. Hence, in this work, molecular dynamics (MD) simulations are used to investigate the interaction mechanism and binding pose of the ALF isoform 3 from Penaeus monodon (ALFPm3), which is referred to as "AL3" for the sake of simplicity, and lipid A (LA, the component of LPS that represents its endotoxic principle). We concluded that hydrophobic interactions are responsible for AL3-LA binding and that LA binds to AL3 within the protein cavity, where it buries its aliphatic tails, whereas the negatively charged phosphate groups are exposed to the medium. AL3 residues that are key for its interaction with LA were identified, and their conservation in other ALFs (specifically Lys39 and Tyr49) was also analyzed. Additionally, based on the MD-derived results, we provide a picture of the possible AL3-LA interaction mechanism. Finally, an in vitro validation of the in silico predictions was performed. Overall, the insights gained from this work can guide the design of novel therapeutics for treating sepsis, since they may be significantly valuable for designing LPS-sequestrating molecules that could functionalize affinity sorbents to be used for extracorporeal blood detoxification.
Insights
New research uses molecular dynamics to understand how anti-LPS factors (ALFs) bind to lipid A (LA), a key component of Gram-negative bacteria. This study reveals hydrophobic interactions are crucial for binding, guiding the development of new sepsis treatments.
Area of Science:
- Biochemistry and Molecular Biology
- Infectious Diseases and Microbiology
- Computational Biology
Background:
- Antibiotic resistance necessitates novel strategies against Gram-negative bacterial infections.
- Lipopolysaccharide (LPS) from Gram-negative bacteria triggers severe immune responses.
- Extracorporeal blood cleansing using affinity sorbents is a promising therapeutic approach.
Purpose of the Study:
- To investigate the interaction mechanism between anti-LPS factor 3 from Penaeus monodon (AL3) and lipid A (LA) using molecular dynamics simulations.
- To identify key residues involved in AL3-LA binding and analyze their conservation.
- To provide insights for designing effective LPS-sequestering molecules for blood detoxification.
Main Methods:
- Molecular dynamics (MD) simulations were employed to study the binding of AL3 to LA.
- Analysis of hydrophobic interactions and binding pose within the protein cavity.
- Identification and conservation analysis of key amino acid residues (Lys39, Tyr49).
Main Results:
- Hydrophobic interactions are the primary driving force for AL3-LA binding.
- Lipid A binds within the AL3 protein cavity, with aliphatic tails buried and phosphate groups exposed.
- Key residues, Lys39 and Tyr49, were identified as critical for the interaction and found to be conserved in other ALFs.
Conclusions:
- The study elucidates the molecular mechanism of AL3-LA interaction, driven by hydrophobic forces.
- In silico predictions were validated through in vitro experiments.
- Findings can guide the development of novel therapeutics and affinity sorbents for sepsis treatment and extracorporeal blood detoxification.
