scholarly journals Structural and functional analyses confirm the presence of functional P‐loops and intrinsic GTPase activity in Evc protein (1013.9)

2014 ◽  
Vol 28 (S1) ◽  
Author(s):  
Odutayo Odunuga
Keyword(s):  
Gtpase Activity ◽  
Functional Analyses ◽  
Intrinsic Gtpase Activity

G13A Substitution Affects the Biochemical and Physical Properties of the Elongation Factor 1α. A Reduced Intrinsic GTPase Activity Is Partially Restored by Kirromycin†

Biochemistry ◽  
2002 ◽  
Vol 41 (2) ◽  
pp. 628-633 ◽  
Author(s):  
Mariorosario Masullo ◽  
Piergiuseppe Cantiello ◽  
Barbara de Paola ◽  
Francesca Catanzano ◽  
Paolo Arcari ◽  
...  
Keyword(s):  
Physical Properties ◽  
Elongation Factor ◽  
Gtpase Activity ◽  
Elongation Factor 1Α ◽  
Intrinsic Gtpase Activity

scholarly journals Ubiquitously Expressed Dynamin-II Has a Higher Intrinsic GTPase Activity and a Greater Propensity for Self-assembly Than Neuronal Dynamin-I

1997 ◽  
Vol 8 (12) ◽  
pp. 2553-2562 ◽  
Author(s):  
Dale E. Warnock ◽  
Takeshi Baba ◽  
Sandra L. Schmid
Keyword(s):  
Self Assembly ◽  
Intrinsic Rate ◽  
Biochemical Properties ◽  
Gtpase Activity ◽  
Coated Pits ◽  
Gtp Hydrolysis ◽  
Rich Domain ◽  
Dynamin I ◽  
Intrinsic Gtpase Activity

To begin to understand mechanistic differences in endocytosis in neurons and nonneuronal cells, we have compared the biochemical properties of the ubiquitously expressed dynamin-II isoform with those of neuron-specific dynamin-I. Like dynamin-I, dynamin-II is specifically localized to and highly concentrated in coated pits on the plasma membrane and can assemble in vitro into rings and helical arrays. As expected, the two closely related isoforms share a similar mechanism for GTP hydrolysis: both are stimulated in vitro by self-assembly and by interaction with microtubules or the SH3 domain-containing protein, grb2. Deletion of the C-terminal proline/arginine-rich domain from either isoform abrogates self-assembly and assembly-dependent increases in GTP hydrolysis. However, dynamin-II exhibits a ∼threefold higher rate of intrinsic GTP hydrolysis and higher affinity for GTP than dynamin-I. Strikingly, the stimulated GTPase activity of dynamin-II can be >40-fold higher than dynamin-I, due principally to its greater propensity for self-assembly and the increased resistance of assembled dynamin-II to GTP-triggered disassembly. These results are consistent with the hypothesis that self-assembly is a major regulator of dynamin GTPase activity and that the intrinsic rate of GTP hydrolysis reflects a dynamic, GTP-dependent equilibrium of assembly and disassembly.

scholarly journals Regulation of Cdc42 GTPase Activity in the Formation of Hyphae inCandida albicans

2007 ◽  
Vol 18 (1) ◽  
pp. 265-281 ◽  
Author(s):  
Helen Court ◽  
Peter Sudbery
Keyword(s):  
Fungal Pathogen ◽  
Germ Tube ◽  
Gtpase Activity ◽  
Negative Regulators ◽  
Human Fungal Pathogen ◽  
Gtpase Activating Proteins ◽  
Characteristic Features ◽  
Increased Activity ◽  
Intrinsic Gtpase Activity ◽  
Incandida Albicans

The human fungal pathogen Candida albicans can switch between yeast, pseudohyphal, and hyphal morphologies. To investigate whether the distinctive characteristics of hyphae are due to increased activity of the Cdc42 GTPase, strains lacking negative regulators of Cdc42 were constructed. Unexpectedly, the deletion of the Cdc42 Rho guanine dissociation inhibitor RDI1 resulted in reduced rather than enhanced polarized growth. However, when cells lacking both Cdc42 GTPase-activating proteins, encoded by RGA2 and BEM3, were grown under pseudohyphal-promoting conditions the bud was highly elongated and lacked a constriction at its base, so that its shape resembled a hyphal germ tube. Moreover, a Spitzenkörper was present at the bud tip, a band of disorganized septin was present at bud base, true septin rings formed within the bud, and nuclei migrated out of the mother cell before the first mitosis. These are all characteristic features of a hyphal germ tube. Intriguingly, we observed hyphal-specific phosphorylation of Rga2, suggesting a possible mechanism for Cdc42 activation during normal hyphal development. In contrast, expression of Cdc42G12V, which is constitutively GTP bound because it lacks GTPase activity, resulted in swollen cells with prominent and stable septin bars. These results suggest the development of hyphal-specific characteristics is promoted by Cdc42-GTP in a process that also requires the intrinsic GTPase activity of Cdc42.

Regulation of mitochondrial fission by GIPC-mediated Drp1 retrograde transport

2021 ◽  
Author(s):  
Aaron Ramonett ◽  
Eun-A Kwak ◽  
Tasmia Ahmed ◽  
Paola Cruz Flores ◽  
Hannah R. Ortiz ◽  
...  
Keyword(s):  
Cancer Progression ◽  
Metabolic Disorders ◽  
Mitochondrial Fission ◽  
Retrograde Transport ◽  
Binding Motif ◽  
Cell Periphery ◽  
Gtpase Activity ◽  
Migratory Capacity ◽  
Essential Enzyme ◽  
Intrinsic Gtpase Activity

Drp1 is a key regulator of mitochondrial fission, a large cytoplasmic GTPase recruited to the mitochondrial surface via transmembrane adaptors to initiate scission. While Brownian motion likely accounts for the local interactions between Drp1 and the mitochondrial adaptors, how this essential enzyme is targeted from more distal regions like the cell periphery remains unknown. Based on proteomic interactome screening and cell-based studies, we report that GIPC mediates the actin-based retrograde transport of Drp1 towards the perinuclear mitochondria to enhance fission. Drp1 interacts with GIPC through its atypical C-terminal PDZ-binding motif. Loss of this interaction abrogates Drp1 retrograde transport resulting in cytoplasmic mislocalization and reduced fission despite retaining normal intrinsic GTPase activity. Functionally, we demonstrate that GIPC potentiates the Drp1-driven proliferative and migratory capacity in cancer cells. Together, these findings establish a direct molecular link between altered GIPC expression and Drp1 function in cancer progression and metabolic disorders.

scholarly journals Drosophila Orc6 Facilitates GTPase Activity and Filament Formation of the Septin Complex

2009 ◽  
Vol 20 (1) ◽  
pp. 270-281 ◽  
Author(s):  
Richard P.H. Huijbregts ◽  
Anton Svitin ◽  
Monica W. Stinnett ◽  
Matthew B. Renfrow ◽  
Igor Chesnokov
Keyword(s):  
Origin Recognition Complex ◽  
Complex Function ◽  
Coiled Coil ◽  
Active Role ◽  
Gtpase Activity ◽  
Filament Formation ◽  
Cell Functions ◽  
Coiled Coil Domain ◽  
Intrinsic Gtpase Activity ◽  
Drosophila Embryos

The origin recognition complex or ORC is a six-subunit protein important for DNA replication and other cell functions. Orc6, the smallest subunit of ORC, is essential for both replication and cytokinesis in Drosophila, and interacts with the septin protein Pnut, which is part of the Drosophila septin complex. In this study, we describe the analysis of the interaction of Orc6 with Pnut and whole Drosophila septin complex. Septin complex was purified from Drosophila embryos and also reconstituted from recombinant proteins. The interaction of Orc6 with the septin complex is dependent on the coiled-coil domain of Pnut. Furthermore, the binding of Orc6 to Pnut increases the intrinsic GTPase activity of the Drosophila septin complex, whereas in the absence of GTP it enhances septin complex filament formation. These results suggest an active role for Orc6 in septin complex function. Orc6 might be a part of a control mechanism directing the cytokinesis machinery during the final steps of mitosis.

scholarly journals Differential regulation of cellular activities by GTPase-activating protein and NF1.

1993 ◽  
Vol 13 (4) ◽  
pp. 2497-2503 ◽  
Author(s):  
N al-Alawi ◽  
G Xu ◽  
R White ◽  
R Clark ◽  
F McCormick ◽  
...  
Keyword(s):  
Signal Transduction ◽  
Biological Effects ◽  
Type I ◽  
Type Ii ◽  
Gtpase Activity ◽  
Ras Proteins ◽  
Ras Gtpase ◽  
Intrinsic Gtpase Activity

The regulation of the GTPase activity of the Ras proteins is thought to be a key element of signal transduction. Ras proteins have intrinsic GTPase activity and are active in signal transduction when bound to GTP but not following hydrolysis of GTP to GDP. Three cellular Ras GTPase-activating proteins (Ras-gaps) which increase the GTPase activity of wild-type (wt) Ras but not activated Ras in vitro have been identified: type I and type II GAP and type I NF1. Mutations of wt Ras resulting in lowered intrinsic GTPase activity or loss of response to cellular Ras-gap proteins are thought to be the primary reason for the transforming properties of the Ras proteins. In vitro assays show type I and type II GAP and the GAP-related domain of type I NF1 to have similar biochemical properties with respect to activation of the wt Ras GTPase, and it appears as though both type I GAP and NF1 can modulate the GTPase function of Ras in cells. Here we report the assembling of a full-length coding clone for type I NF1 and the biological effects of microinjection of Ras and Ras-gap proteins into fibroblasts. We have found that type I GAP, type II GAP, and type I NF1 show markedly different biological activities in vivo. Coinjection of type I GAP or type I NF1, but not type II GAP, with wt Ras abolished the ability of wt Ras to induce expression from an AP-1-controlled reporter gene. We also found that serum-stimulated DNA synthesis was reduced by prior injection of cells with type I GAP but not type II GAP or type I NF1. These results suggest that type I GAP, type II GAP, and type I NF1 may have different activities in vivo and support the hypothesis that while type I forms of GAP and NF1 may act as negative regulators of wt Ras, they may do so with differential efficiencies.

scholarly journals Intraflagellar transport protein RABL5/IFT22 recruits the BBSome to the basal body through the GTPase ARL6/BBS3

2020 ◽  
Vol 117 (5) ◽  
pp. 2496-2505 ◽  
Author(s):  
Bin Xue ◽  
Yan-Xia Liu ◽  
Bin Dong ◽  
Jenna L. Wingfield ◽  
Mingfu Wu ◽  
...  
Keyword(s):  
Basal Body ◽  
In Vivo Imaging ◽  
Bound States ◽  
Intraflagellar Transport ◽  
Signaling Proteins ◽  
Gtpase Activity ◽  
Guanosine Triphosphate ◽  
Bardet Biedl Syndrome ◽  
Intrinsic Gtpase Activity

Bardet-Biedl syndrome (BBS) is a ciliopathy caused by defects in the assembly or distribution of the BBSome, a conserved protein complex. The BBSome cycles via intraflagellar transport (IFT) through cilia to transport signaling proteins. How the BBSome is recruited to the basal body for binding to IFT trains for ciliary entry remains unknown. Here, we show that the Rab-like 5 GTPase IFT22 regulates basal body targeting of the BBSome in Chlamydomonas reinhardtii. Our functional, biochemical and single particle in vivo imaging assays show that IFT22 is an active GTPase with low intrinsic GTPase activity. IFT22 is part of the IFT-B1 subcomplex but is not required for ciliary assembly. Independent of its association to IFT-B1, IFT22 binds and stabilizes the Arf-like 6 GTPase BBS3, a BBS protein that is not part of the BBSome. IFT22/BBS3 associates with the BBSome through an interaction between BBS3 and the BBSome. When both IFT22 and BBS3 are in their guanosine triphosphate (GTP)-bound states they recruit the BBSome to the basal body for coupling with the IFT-B1 subcomplex. The GTP-bound BBS3 likely remains to be associated with the BBSome upon ciliary entry. In contrast, IFT22 is not required for the transport of BBSomes in cilia, indicating that the BBSome is transferred from IFT22 to the IFT trains at the ciliary base. In summary, our data propose that nucleotide-dependent recruitment of the BBSome to the basal body by IFT22 regulates BBSome entry into cilia.

scholarly journals The role of Gln61 and Glu63 of Ras GTPases in their activation by NF1 and Ras GAP.

1992 ◽  
Vol 3 (12) ◽  
pp. 1437-1442 ◽  
Author(s):  
M S Nur-E-Kamal ◽  
H Maruta
Keyword(s):  
Rho Gtpases ◽  
Primary Role ◽  
Gtpase Activity ◽  
Signal Transducers ◽  
Ras Gtpases ◽  
Dependent Signal ◽  
Gtpase Activation ◽  
Guanosine Triphosphatase ◽  
Intrinsic Gtpase Activity

Two distinct GAPs of 120 and 235 kDa called GAP1 and NF1 serve as attenuators of Ras, a member of GTP-dependent signal transducers, by stimulating its intrinsic guanosine triphosphatase (GTPase) activity. The GAP1 (also called Ras GAP) is highly specific for Ras and does not stimulate the intrinsic GTPase activity of Rap1 or Rho. Using GAP1C, the C-terminal GTPase activating domain (residues 720-1044) of bovine GAP1, we have shown previously that the GAP1 specificity is determined by the Ras domain (residues 61-65) where Gln61 plays the primary role. The corresponding domain (residues 1175-1531) of human NF1 (called NF1C), which shares only 26% sequence identity with the GAP1C, also activates Ras GTPases. In this article, we demonstrate that the NF1C, like the GAP1C, is highly specific for Ras and does not activate either Rap1 or Rho GTPases. Furthermore, using a series of chimeric Ras/Rap1 and mutated Ras GTPases, we show that Gln at position 61 of the GTPases primarily determines that NF1C as well as GAP1C activates Ras GTPases, but not Rap1 GTPases, and Glu at position 63 of the GTPases is required for maximizing the sensitivity of Ras GTPases to both NF1C and GAP1C. Interestingly, replacement of Glu63 of c-HaRas by Lys reduces its intrinsic GTPase activity and abolishes the GTPase activation by both NF1C and GAP1C. Thus, the potentiation of oncogenicity by Lys63 mutation of c-HaRas appears primarily to be due to the loss of its sensitivity to the two major Ras signal attenuators (NF1 and GAP1).

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