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Published on: August 25, 2020
Molecular characterization of direct interactions between MPP1 and flotillins
Agnieszka Biernatowska1, Paulina Olszewska1, Krzysztof Grzymajło2
1Department of Cytobiochemistry, Faculty of Biotechnology, University of Wrocław, 50-383, Wrocław, Poland.
Abstract:
Flotillins are the major structural proteins in erythroid raft domains. We have shown previously that the dynamic nanoscale organization of raft domains in erythroid cells may depend on flotillin-MPP1 interactions. Here, by using molecular dynamic simulations and a surface plasmon resonance-based approach we determined that high-affinity complexes of MPP1 and flotillins are formed via a so far unidentified region within the D5 domain of MPP1. Significantly, this particular "flotillin binding motif" is of key physiological importance, as overexpression of peptides containing this motif inhibited endogenous MPP1-flotillin interaction in erythroid precursor cells, thereby causing lateral disorganization of raft domains. This was reflected by both reduction in the plasma membrane order and markedly decreased activation of signal transduction via the raft-dependent insulin receptor pathway. Our data highlight new molecular details concerning the mechanism whereby MPP1 functionally links flotillins to exert their physiological role in raft domain formation.
Insights
Flotillins and MPP1 form high-affinity complexes in erythroid cells through a novel MPP1 binding motif. This interaction is crucial for maintaining raft domain organization and insulin receptor signaling.
Area of Science:
- Cell biology
- Molecular biology
- Biophysics
Background:
- Flotillins are key structural proteins in erythroid cell raft domains.
- Flotillin-MPP1 interactions are critical for raft domain nanoscale organization.
Purpose of the Study:
- To identify the specific binding region between MPP1 and flotillins.
- To investigate the physiological role of the MPP1-flotillin interaction in erythroid cells.
Main Methods:
- Molecular dynamic simulations
- Surface plasmon resonance (SPR) assays
- Peptide overexpression in erythroid precursor cells
Main Results:
- A high-affinity binding motif was identified within the D5 domain of MPP1.
- Overexpression of this motif disrupted MPP1-flotillin interactions and raft domain organization.
- Disorganization led to reduced plasma membrane order and impaired insulin receptor pathway activation.
Conclusions:
- MPP1 binds flotillins via a novel motif in its D5 domain.
- This interaction is essential for maintaining raft domain integrity and function in erythroid cells.
- The findings elucidate a key mechanism linking flotillins to raft-dependent signaling pathways.
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