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Homo and hetero dimerisation of the human guanylate‐binding proteins hGBP ‐1 and hGBP ‐5 characterised by affinities and kinetics
Author(s) -
Kutsch Miriam,
Ince Semra,
Herrmann Christian
Publication year - 2018
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/febs.14459
Subject(s) - homomeric , affinities , dimer , chemistry , biophysics , mutant , plasma protein binding , biochemistry , biology , gene , protein subunit , organic chemistry
The human guanylate‐binding proteins ( hGBP s) exhibit diverse antipathogenic and tumour‐related functions which make them key players in the innate immune response. The isoforms hGBP ‐1 to hGBP ‐5 form homomeric complexes and localise to specific cellular compartments. Upon heteromeric interactions, hGBP s are able to guide each other to their specific compartments. Thus, homo‐ and heteromeric interactions allow the hGBP s to build a network within the cell which might be important for their diverse biological functions. We characterised homomeric complexes of hGBP s in vitro and presented most recently that nonprenylated hGBP ‐1 and hGBP ‐5 form dimers as highest oligomeric species while farnesylated hGBP ‐1 is able to form polymers. We continued to work on the biochemical characterisation of the heteromeric interactions between hGBP s and present here results for nonprenylated hGBP ‐1 and hGBP ‐5. Multiangle light scattering identified the GTP ‐dependent heteromeric complex as dimer. Also hGBP ‐5's tumour‐associated splice variant ( hGBP ‐5ta) was able to form a hetero dimer with hGBP ‐1. Intriguingly, both hGBP ‐5 splice variants were able to induce domain rearrangements within hGBP ‐1. We further characterised the homo and hetero dimers with Förster resonance energy transfer‐based experiments. This allowed us to obtain affinities and kinetics of the homo and hetero dimer formation. Furthermore, we identified that the LG domains of hGBP ‐1 and hGBP ‐5 build an interaction site within the hetero dimer. Our in vitro study provides mechanistic insights into the homomeric and heteromeric interactions of hGBP ‐1 and hGBP ‐5 and present useful strategies to characterise the hGBP network further.