Format

Send to

Choose Destination
Structure. 2018 Nov 6;26(11):1451-1461.e4. doi: 10.1016/j.str.2018.07.015. Epub 2018 Aug 30.

The N-Terminal GTPase Domain of p190RhoGAP Proteins Is a PseudoGTPase.

Author information

1
Department of Pharmacology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA.
2
Department of Pharmacology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA; Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA; Yale Cancer Center, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA. Electronic address: titus.boggon@yale.edu.

Abstract

The pseudoGTPases are a rapidly growing and important group of pseudoenzymes. p190RhoGAP proteins are critical regulators of Rho signaling and contain two previously identified pseudoGTPase domains. Here we report that p190RhoGAP proteins contain a third pseudoGTPase domain, termed N-GTPase. We find that GTP constitutively purifies with the N-GTPase domain, and a 2.8-Å crystal structure of p190RhoGAP-A co-purified with GTP reveals an unusual GTP-Mg2+ binding pocket. Six inserts in N-GTPase indicate perturbed catalytic activity and inability to bind to canonical GTPase activating proteins, guanine nucleotide exchange factors, and effector proteins. Biochemical analysis shows that N-GTPase does not detectably hydrolyze GTP, and exchanges nucleotide only under harsh Mg2+ chelation. Furthermore, mutational analysis shows that GTP and Mg2+ binding stabilizes the domain. Therefore, our results support that N-GTPase is a nucleotide binding, non-hydrolyzing, pseudoGTPase domain that may act as a protein-protein interaction domain. Thus, unique among known proteins, p190RhoGAPs contain three pseudoGTPase domains.

KEYWORDS:

ARHGAP35; ARHGAP5; PseudoGTPase; Rho signaling; crystal structure; pseudoenzyme

PMID:
30174148
PMCID:
PMC6249675
[Available on 2019-11-06]
DOI:
10.1016/j.str.2018.07.015

Supplemental Content

Full text links

Icon for Elsevier Science
Loading ...
Support Center