GTP analogue hydrolysis by the Gs protein: implication for the role of catalytic glutamine in the GTPase reaction

Zor, Tsaffrir; Andorn, Ronit; Sofer, Ilya; Chorev, Michael; Selinger, Zvi

doi:10.1016/s0014-5793(98)00930-2

Cited by 19 publications

(15 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In conclusion, it appears that the benzoyl group has some effect on the phosphoryl transfer reaction but that the most important contribution comes from the aromatic amine group. Following an earlier suggestion (14,26) and from this study, it appeared plausible that the aromatic amino group of DABP-GTP would, at least partially, substitute for the loss of function of the carbonamide side chain of Gln61, which is involved in stabilization of the transition state but possibly also in increasing the nucleophilicity of the water molecule.…”

Section: Resultssupporting

confidence: 66%

“…1; Table 1) is increased as compared with monoaminobenzophenone-GTP and phenylene-monoamine-GTP but is lower than DABP-GTP, suggesting that the benzoyl group does contribute to the rate acceleration. This is different from with G␣, where the benzoyl group has no effect on the cleavage rate (26). Hydrolysis resistance of monoaminobenzophenone-GTP and phenylene-monoamine-GTP underscores the critical role of the aromatic amino group as a catalytically functional group (Fig.…”

Section: Resultsmentioning

confidence: 86%

“…One possible explanation could be the shielding of the attacking water molecule from the bulk solvent by the aromatic ring, thus increasing its nucleophilicity. Another explanation, as discussed before (26), could be that the aromatic amino group serves as a H-bond donor for the ␥-phosphate to stabilize negative charges developing in the transition state similar to the role of Gln61 in the intrinsic and of Gln61 and an arginine from GAP in the GAP-accelerated GTPase reaction. Such an effect should be stronger in DABP-GTP, whose amino group is more acidic, in line with the experimental results.…”

Section: Resultsmentioning

confidence: 95%

See 2 more Smart Citations

Guanosine triphosphatase stimulation of oncogenic Ras mutants

Ahmadian

Zor

Vogt

et al. 1999

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

135

View full text Add to dashboard Cite

Interest in the guanosine triphosphatase (GTPase) reaction of Ras as a molecular drug target stems from the observation that, in a large number of human tumors, Ras is characteristically mutated at codons 12 or 61, more rarely 13. Impaired GTPase activity, even in the presence of GTPase activating proteins, has been found to be the biochemical reason behind the oncogenicity of most Gly12͞ Gln61 mutations, thus preventing Ras from being switched off. Therefore, these oncogenic Ras mutants remain constitutively activated and contribute to the neoplastic phenotype of tumor cells. Here, we show that the guanosine 5-triphosphate (GTP) analogue diaminobenzophenonephosphoroamidate-GTP (DABP-GTP) is hydrolyzed by wildtype Ras but more efficiently by frequently occurring oncogenic Ras mutants, to yield guanosine 5-diphosphate-bound inactive Ras and DABP-P i . The reaction is independent of the presence of Gln61 and is most dramatically enhanced with Gly12 mutants. Thus, the defective GTPase reaction of the oncogenic Ras mutants can be rescued by using DABP-GTP instead of GTP, arguing that the GTPase switch of Ras is not irreversibly damaged. An exocyclic aromatic amino group of DABP-GTP is critical for the reaction and bypasses the putative rate-limiting step of the intrinsic Ras GTPase reaction. The crystal structures of Ras-bound DABP-␤,␥-imido-GTP show a disordered switch I and identify the Gly12͞Gly13 region as the hydrophobic patch to accommodate the DABPmoiety. The biochemical and structural studies help to define the requirements for the design of anti-Ras drugs aimed at the blocked GTPase reaction.

show abstract

Section: Resultssupporting

confidence: 66%

Section: Resultsmentioning

confidence: 86%

Section: Resultsmentioning

confidence: 95%

See 1 more Smart Citation

Guanosine triphosphatase stimulation of oncogenic Ras mutants

Ahmadian

Zor

Vogt

et al. 1999

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

135

View full text Add to dashboard Cite

show abstract

“…The latter notion has gained impetus by recent reports showing for the fi rst time that oncogenic Ras mutants can be chemically inactivated and are not irreversibly damaged in their capability to act as molecular switches. The defective GTPase reaction of different oncogenic mutants of Ras could be increased by up to three orders of magnitude by using a modifi ed GTP analog, 3,4-diaminobenzophenone-phosphoramidate-GTP (DABP-GTP [114,115]), instead of GTP [63]. The structures of DABP-GppNHp bound to Pro12 and Val12 mutants of Ras have shown that the DABP moiety is accommodated close to a hydrophobic patch of Pro12 or Val12 in the P-loop.…”

Section: Rasgapsmentioning

confidence: 99%

GTPase activating proteins: structural and functional insights 18 years after discovery

Scheffzek

Ahmadian

2005

Cell. Mol. Life Sci.

132

104

View full text Add to dashboard Cite

The conversion of guanosine triphosphate (GTP) to guanosine diphosphate (GDP) and inorganic phosphate (P(i)) by guanine nucleotide binding proteins (GNBPs) is a fundamental process in living cells and represents an important timer in intracellular signalling and transport processes. While the rate of GNBP-mediated GTP hydrolysis is intrinsically slow, direct interaction with GTPase activating proteins (GAPs) accelerates the reaction by up to five orders of magnitude in vitro. Eighteen years after the discovery of the first GAP, biochemical and structural research has been accumulating evidence that GAPs employ a much wider spectrum of chemical mechanisms than had originally been assumed, in order to regulate the chemical players on the catalytic protein-protein interaction stage.

show abstract

“…In other analogues, phosphate groups were introduced at the 5′-position with the aim of targeting P2 receptors, 9 G proteins (in the case of a guanosine 5′-triphosphate analogue) 10 or enzymes involved in purine metabolism (such as IMP dehydrogenase). 11 The structures of (N)-methanocarba purine analogues (5-12) synthesized for testing in binding and other biochemical assays are shown in Table 1.…”

mentioning

confidence: 99%

Synthesis and purine receptor affinity of 6-oxopurine nucleosides and nucleotides containing (N)-methanocarba-pseudoribose rings

Ravi

Lee

et al. 2001

Bioorganic & Medicinal Chemistry Letters

View full text Add to dashboard Cite

Abstract6-Oxopurine derivatives containing a northern (N) methanocarba modification (i.e., fused cyclopropane and cyclopentane rings in place of the ribose) were synthesized and the adenosine receptor affinity measured. Guanine or hypoxanthine was coupled at the 7-position, or 1,3-dibutylxanthine was coupled at the 9-position. The pseudoribose ring was also substituted at the 5′-position with an N-methyluronamide or with phosphate groups.We recently examined conformational requirements of the ribose moiety in adenosine derivatives acting as agonists or partial agonists at P2 receptors and at subtypes of adenosine receptors (A 1 , A 2A , and A 3 ARs). 1-3 Using a methanocarba modification originally introduced by Marquez and co-workers, 4 the ribose-like moiety of these derivatives was constrained to either a northern [(N), 2′-exo] or southern [(S), 2′-endo] conformation through fused cyclopropane and cyclopentane rings. Such analogues helped to define the role of ribofuranosyl puckering in stabilizing the active AR-bound conformation, and thereby allowed identification of the (N)-methanocarba conformation as the isomer which preserved affinity at the A 3 and to a lesser extent, A 1 AR. Thus, the (N)-methanocarba analogues, 1 and 2, were highly potent as full agonist (2) 3 or partial agonist (1) at the human A 3 AR. 2 These analogues contained substituent groups known to enhance A 3 affinity in the ribose series [i.e., N 6 -(3-iodobenzyl) and 2-chloro]. The affinity of adenosine methanocarba analogues at the A 2A AR was greatly decreased for the (N)-methanocarba isomer and nearly absent for the (S)-methanocarba isomer.In this study, we combined the (N)-methanocarba modification with known purine receptor ligands containing a 6-oxo-substitution. Among the nucleoside analogues synthesized were derivatives of hypoxanthine, guanosine, and xanthine. For inosine 5,6 and xanthine-7-riboside 7 analogues, a 5′-methyluronamide modification (nucleoside numbering) known to enhance the A 3 AR affinity was included. 3,5 In comparison, xanthine-7-riboside derivatives 3 and 4 bound to and activated the rat A 3 AR with partial or full efficacy, respectively, 7,8 and

show abstract

GTP analogue hydrolysis by the Gs protein: implication for the role of catalytic glutamine in the GTPase reaction

Cited by 19 publications

References 22 publications

Guanosine triphosphatase stimulation of oncogenic Ras mutants

Guanosine triphosphatase stimulation of oncogenic Ras mutants

GTPase activating proteins: structural and functional insights 18 years after discovery

Synthesis and purine receptor affinity of 6-oxopurine nucleosides and nucleotides containing (N)-methanocarba-pseudoribose rings

Contact Info

Product

Resources

About