Journal article
Unique Structural and Nucleotide Exchange Features of the Rho1 GTPase of Entamoeba histolytica
The Journal of biological chemistry, Vol.286(45), pp.39236-39246
11/11/2011
DOI: 10.1074/jbc.M111.253898
PMCID: PMC3234748
PMID: 21930699
Abstract
The single-celled human parasite Entamoeba histolytica possesses a dynamic actin cytoskeleton vital for its intestinal and systemic pathogenicity. The E. histolytica genome encodes several Rho family GTPases known to regulate cytoskeletal dynamics. EhRho1, the first family member identified, was reported to be insensitive to the Rho GTPase-specific Clostridium botulinum C3 exoenzyme, raising the possibility that it may be a misclassified Ras family member. Here, we report the crystal structures of EhRho1 in both active and inactive states. EhRho1 is activated by a conserved switch mechanism, but diverges from mammalian Rho GTPases in lacking a signature Rho insert helix. EhRho1 engages a homolog of mDia, EhFormin1, suggesting a role in mediating serum-stimulated actin reorganization and microtubule formation during mitosis. EhRho1, but not a constitutively active mutant, interacts with a newly identified EhRhoGDI in a prenylation-dependent manner. Furthermore, constitutively active EhRho1 induces actin stress fiber formation in mammalian fibroblasts, thereby identifying it as a functional Rho family GTPase. EhRho1 exhibits a fast rate of nucleotide exchange relative to mammalian Rho GTPases due to a distinctive switch one isoleucine residue reminiscent of the constitutively active F28L mutation in human Cdc42, which for the latter protein, is sufficient for cellular transformation. Nonconserved, nucleotide-interacting residues within EhRho1, revealed by the crystal structure models, were observed to contribute a moderating influence on fast spontaneous nucleotide exchange. Collectively, these observations indicate that EhRho1 is a bona fide member of the Rho GTPase family, albeit with unique structural and functional aspects compared with mammalian Rho GTPases.
Background: Rho family GTPases regulate Entamoeba histolytica pathogenesis.
Results: Despite Ras-like structural features and fast intrinsic nucleotide exchange, EhRho1 engages classical Rho effectors and regulates actin.
Conclusion: EhRho1 is a true Rho family GTPase with a unique mode of nucleotide interaction.
Significance: Possibly representing an early Rho subfamily divergence from the Ras superfamily, EhRho1 likely regulates actin polymerization in E. histolytica.
Details
- Title: Subtitle
- Unique Structural and Nucleotide Exchange Features of the Rho1 GTPase of Entamoeba histolytica
- Creators
- Dustin E Bosch - University of North Carolina at Chapel HillErika S Wittchen - University of North Carolina at Chapel HillConnie Qiu - University of North Carolina at Chapel HillKeith Burridge - University of North Carolina at Chapel HillDavid P Siderovski - University of North Carolina at Chapel HillArgonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
- Resource Type
- Journal article
- Publication Details
- The Journal of biological chemistry, Vol.286(45), pp.39236-39246
- DOI
- 10.1074/jbc.M111.253898
- PMID
- 21930699
- PMCID
- PMC3234748
- NLM abbreviation
- J Biol Chem
- ISSN
- 0021-9258
- eISSN
- 1083-351X
- Publisher
- Elsevier Inc
- Grant note
- R01GM082892; R01GM029860 / National Institutes of Health T32GM008719; T32GM007040 / National Institutes of Health
- Language
- English
- Date published
- 11/11/2011
- Academic Unit
- Pathology
- Record Identifier
- 9984200021902771
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