PDBsum entry 1tx4

Complex(gtpase activatn/proto-oncogene)

PDB id: 1tx4

Contents

Protein chains

196 a.a. *

174 a.a. *

Ligands

ALF-GDP

Metals

_MG

Waters ×497

* Residue conservation analysis

PDB id:

1tx4

Name:

Complex(gtpase activatn/proto-oncogene)

Title:

Rho/rhogap/gdp(dot)alf4 complex

Structure:

P50-rhogap. Chain: a. Synonym: gtpase-activating protein rhogap. Engineered: yes. Transforming protein rhoa. Chain: b. Engineered: yes

Source:

Homo sapiens. Human. Organism_taxid: 9606. Expressed in: escherichia coli bl21. Expression_system_taxid: 511693.

Biol. unit:

Dimer (from PQS)

Resolution:

1.65Å R-factor: 0.169 R-free: 0.215

Authors:

K.Rittinger,P.A.Walker,S.J.Smerdon,S.J.Gamblin

Key ref:

K.Rittinger et al. (1997). Structure at 1.65 A of RhoA and its GTPase-activating protein in complex with a transition-state analogue. Nature, 389, 758-762. PubMed id: 9338791 DOI: 10.1038/39651

Date:

29-Jul-97 Release date: 16-Sep-98

Protein chain

Q07960  (RHG01_HUMAN) -  Rho GTPase-activating protein 1 from Homo sapiens

Seq: 439 a.a.

Struc: 196 a.a.*

Protein chain

P61586  (RHOA_HUMAN) -  Transforming protein RhoA from Homo sapiens

Seq: 193 a.a.

Struc: 174 a.a.*

* PDB and UniProt seqs differ at 2 residue positions (black crosses)

Enzyme reactions

• Enzyme class 2: Chain A: E.C.?
• Enzyme class 3: Chain B: E.C.3.6.5.2 - small monomeric GTPase.
• Reaction: GTP + H2O = GDP + phosphate + H⁺

GTP + H2O = GDP (Bound ligand (Het Group name = GDP) corresponds exactly) + phosphate + H(+)

Note, where more than one E.C. class is given (as above), each may correspond to a different protein domain or, in the case of polyprotein precursors, to a different mature protein.

Molecule diagrams generated from .mol files obtained from the KEGG ftp site

reference

DOI no: 10.1038/39651

Nature 389:758-762 (1997)

PubMed id: 9338791

Structure at 1.65 A of RhoA and its GTPase-activating protein in complex with a transition-state analogue.

K.Rittinger, P.A.Walker, J.F.Eccleston, S.J.Smerdon, S.J.Gamblin.

ABSTRACT

Small G proteins of the Rho family, which includes Rho, Rac and Cdc42Hs, regulate phosphorylation pathways that control a range of biological functions including cytoskeleton formation and cell proliferation. They operate as molecular switches, cycling between the biologically active GTP-bound form and the inactive GDP-bound state. Their rate of hydrolysis of GTP to GDP by virtue of their intrinsic GTPase activity is slow, but can be accelerated by up to 10(5)-fold through interaction with rhoGAP, a GTPase-activating protein that stimulates Rho-family proteins. As such, rhoGAP plays a crucial role in regulating Rho-mediated signalling pathways. Here we report the crystal structure of RhoA and rhoGAP complexed with the transition-state analogue GDP.AlF4- at 1.65 A resolution. There is a rotation of 20 degrees between the Rho and rhoGAP proteins in this complex when compared with the ground-state complex Cdc42Hs.GMPPNP/rhoGAP, in which Cdc42Hs is bound to the non-hydrolysable GTP analogue GMPPNP. Consequently, in the transition state complex but not in the ground state, the rhoGAP domain contributes a residue, Arg85(GAP) directly into the active site of the G protein. We propose that this residue acts to stabilize the transition state of the GTPase reaction. RhoGAP also appears to function by stabilizing several regions of RhoA that are important in signalling the hydrolysis of GTP.

Selected figure(s)

Figure 2.
Figure 2 Stereo ball-and-stick representation of the complete RhoA.GDP.AlF[4]^-/p50rhoGAP interface viewed in an orientation similar to that in Fig. 1a. The carbon atoms of RhoA are shown in grey and those of rhoGAP are in yellow. GDP.AlF[4]^-is coloured magenta and water molecules are shown as small magenta spheres.

Figure 3.
Figure 3 Stereo view of a portion of the final 2 F [o] - F [c] electron density map around the nucleotide-binding site on RhoA contoured at 2.0 , with the final refined atomic model for selected residues from RhoA and GAP superimposed. Carbon, white; oxygen, red; nitrogen, blue; fluorine, green. The proposed hydrolytic water molecule is shown in red. b, Stereo ball-and-stick representation of the interactions around the diphosphate/AlF[4]^-of the nucleotide. Residues from rhoGAP are coloured yellow with those of rhoA are in grey. The position of Arg 178[Gi 1] following overlap of the G-protein component of G[i 1] with RhoA is shown in green.

The above figures are reprinted by permission from Macmillan Publishers Ltd: Nature (1997, 389, 758-762) copyright 1997.

Figures were selected by an automated process.