Characterization of a novel prokaryotic GDP dissociation inhibitor domain from the G protein coupled membrane protein FeoB |
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Authors: | Eng Edward T Jalilian Amir R Spasov Krasimir A Unger Vinzenz M |
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Affiliation: | 1 Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, PO Box 208024, New Haven, CT 06520-8024, USA 2 Nuclear Medicine Group, Agriculture, Medicine and Industrial Research School (AMIRS), Nuclear Science and Technology Research Institute (NSTRI), Karaj, Iran |
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Abstract: | The FeoB family of membrane embedded G proteins are involved with high affinity Fe(II) uptake in prokaryotes. Here, we report that FeoB harbors a novel GDP dissociation inhibitor-like domain that specifically stabilizes GDP-binding through an interaction with the switch I region of the G protein. We show that the stabilization of GDP binding is conserved between species despite a high degree of sequence variability in their guanine nucleotide dissociation inhibitor (GDI)-like domains, and demonstrate that the presence of the membrane embedded domain increases GDP-binding affinity roughly 150-fold over the level accomplished by action of the GDI-like domain alone. To our knowledge, this is the first example for a prokaryotic GDI, targeting a bacterial G protein-coupled membrane process. Our findings suggest that Fe(II) uptake in bacteria involves a G protein regulatory pathway reminiscent of signaling mechanisms found in higher-order organisms. |
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Keywords: | GEF, guanine nucleotide exchange factor GAP, GTPase activating protein GDI, guanine nucleotide dissociation inhibitor mant, N-methylanthraniloyl GMPPNP, guanosine-5&prime [(β,γ)-imido]triphosphate MBP, maltose binding protein LB, Luria broth |
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