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@ARTICLE{Mosaddeghzadeh:912178,
author = {Mosaddeghzadeh, Niloufar and Pudewell, Silke and Bazgir,
Farhad and Kazemein Jasemi, Neda S and Krumbach, Oliver H F
and Gremer, Lothar and Willbold, Dieter and Dvorsky, Radovan
and Ahmadian, Mohammad R},
title = {{CDC}42-{IQGAP} {I}nteractions {S}crutinized: {N}ew
{I}nsights into the {B}inding {P}roperties of the
{GAP}-{R}elated {D}omain.},
journal = {International journal of molecular sciences},
volume = {23},
number = {16},
issn = {1422-0067},
address = {Basel},
publisher = {Molecular Diversity Preservation International},
reportid = {FZJ-2022-05394},
pages = {8842 -},
year = {2022},
abstract = {The IQ motif-containing GTPase-activating protein (IQGAP)
family composes of three highly-related and evolutionarily
conserved paralogs (IQGAP1, IQGAP2 and IQGAP3), which fine
tune as scaffolding proteins numerous fundamental cellular
processes. IQGAP1 is described as an effector of CDC42,
although its effector function yet re-mains unclear.
Biophysical, biochemical and molecular dynamic simulation
studies have proposed that IQGAP RASGAP-related domains
(GRDs) bind to the switch regions and the insert helix of
CDC42 in a GTP-dependent manner. Our kinetic and equilibrium
studies have shown that IQGAP1 GRD binds, in contrast to its
C-terminal 794 amino acids (called C794), CDC42 in a
nucleotide-independent manner indicating a binding outside
the switch regions. To resolve this discrepancy and move
beyond the one-sided view of GRD, we carried out affinity
measurements and a systematic mutational analysis of the
interfacing residues between GRD and CDC42 based on the
crystal structure of the IQGAP2 GRD-CDC42Q61L GTP complex.
We determined a 100-fold lower affinity of the GRD1 of
IQGAP1 and of GRD2 of IQGAP2 for CDC42 mGppNHp in comparison
to C794/C795 proteins. Moreover, partial and major mutation
of CDC42 switch regions substantially affected C794/C795
binding but only a little GRD1 and remarkably not at all the
GRD2 binding. However, we clearly showed that GRD2
contributes to the overall affinity of C795 by using a 11
amino acid mutated GRD variant. Furthermore, the GRD1
binding to the CDC42 was abolished using specific point
mutations within the insert helix of CDC42 clearly
supporting the notion that CDC42 binding site(s) of IQGAP
GRD lies outside the switch regions among others in the
insert helix. Collectively, this study provides further
evidence for a mechanistic framework model that is based on
a multi-step binding process, in which IQGAP GRD might act
as a 'scaffolding domain' by binding CDC42 irrespective of
its nucleotide-bound forms, followed by other IQGAP domains
downstream of GRD that act as an effector domain and is in
charge for a GTP-dependent interaction with CDC42.},
keywords = {Binding Sites / GTPase-Activating Proteins: metabolism /
Guanosine Triphosphate: metabolism / Nucleotides: metabolism
/ Protein Binding / cdc42 GTP-Binding Protein: genetics /
cdc42 GTP-Binding Protein: metabolism / ras
GTPase-Activating Proteins: genetics / ras GTPase-Activating
Proteins: metabolism / CDC42 (Other) / GAP (Other) /
GAP-related domain (Other) / GRD (Other) / GTPase activating
protein (Other) / IQGAP (Other) / RASGAP (Other) / RHO
GTPases (Other) / nucleotide-independent binding (Other) /
scaffold protein (Other) / scaffolding protein (Other) /
switch regions (Other) / GTPase-Activating Proteins (NLM
Chemicals) / Nucleotides (NLM Chemicals) / ras
GTPase-Activating Proteins (NLM Chemicals) / Guanosine
Triphosphate (NLM Chemicals) / cdc42 GTP-Binding Protein
(NLM Chemicals)},
cin = {IBI-7},
ddc = {540},
cid = {I:(DE-Juel1)IBI-7-20200312},
pnm = {5244 - Information Processing in Neuronal Networks
(POF4-524)},
pid = {G:(DE-HGF)POF4-5244},
typ = {PUB:(DE-HGF)16},
pubmed = {pmid:36012107},
pmc = {pmc:PMC9408373},
UT = {WOS:000845717700001},
doi = {10.3390/ijms23168842},
url = {https://juser.fz-juelich.de/record/912178},
}