Search results for "GTP"
showing 10 items of 346 documents
GTPases of the Rho Subfamily Are Required for Brucella abortus Internalization in Nonprofessional Phagocytes
2001
Members of the genus Brucella are intracellular -Proteobacteria responsible for brucellosis, a chronic disease of humans and animals. Little is known about Brucella virulence mechanisms, but the abilities of these bacteria to invade and to survive within cells are decisive factors for causing disease. Transmission electron and fluorescence microscopy of infected nonprofessional phagocytic HeLa cells revealed minor membrane changes accompanied by discrete recruitment of F-actin at the site of Brucella abortus entry. Cell uptake of B. abortus was negatively affected to various degrees by actin, actin-myosin, and microtubule chemical inhibitors. Modulators of MAPKs and protein-tyrosine kinases…
PURINE AND PYRIMIDINE NUCLEOTIDES IN THE BRAIN OF NORMAL AND CONVULSANT RATS
1969
— Purine and pyrimidine nucleotides were measured in the brain of normal and electroshocked rats after chromatographic separation on ion-exchange resin of mono-, di- and tri-phosphorylated derivatives. CMP, IMP and NAD did not show any significant quantitative change. Adenine nucleotides showed an abrupt change followed by a rapid return to the control value. GTP was the only purine nucleotide exhibiting a relatively slow return to its starting concentration. The greatest percentage increase after electroshock was observed in UMP, which returned to its control value only after 5 min; UDPCoenzymes (i.e. UDPA plus UDPG) showed a relatively small drop during the development of the seizure and …
Delivery of proteins into living cells by reversible membrane permeabilization with streptolysin-O
2001
The pore-forming toxin streptolysin O (SLO) can be used to reversibly permeabilize adherent and nonadherent cells, allowing delivery of molecules with up to 100 kDa mass to the cytosol. Using FITC-labeled albumin, 10 5 –10 6 molecules were estimated to be entrapped per cell. Repair of toxin lesions depended on Ca 2+ -calmodulin and on intact microtubules, but was not sensitive to actin disruption or to inhibition of protein synthesis. Resealed cells were viable for days and retained the capacity to endocytose and to proliferate. The active domains of large clostridial toxins were introduced into three different cell lines. The domains were derived from Clostridium difficile B-toxin and Clo…
Structural insights into the GTPase domain of Escherichia coli MnmE protein
2007
The Escherichia coli MnmE protein is a 50-kDa multidomain GTPase involved in tRNA modification. Its homologues in eukaryotes are crucial for mitochondrial respiration and, thus, it is thought that the human protein might be involved in mitochondrial diseases. Unlike Ras, MnmE shows a high intrinsic GTPase activity and requires effective GTP hydrolysis, and not simply GTP binding, to be functionally active. The isolated MnmE G-domain (165 residues) conserves the GTPase activity of the entire protein, suggesting that it contains the catalytic residues for GTP hydrolysis. To explore the GTP hydrolysis mechanism of MnmE, we analyzed the effect of low pH on binding and hydrolysis of GTP, as well…
A novel cytotoxin from Clostridium difficile serogroup F is a functional hybrid between two other large clostridial cytotoxins.
1999
Abstract The large clostridial cytotoxins (LCTs) constitute a group of high molecular weight clostridial cytotoxins that inactivate cellular small GTP-binding proteins. We demonstrate that a novel LCT (TcdB-1470) from Clostridium difficile strain 1470 is a functional hybrid between “reference” TcdB-10463 andClostridium sordellii TcsL-1522. It bound to the same specific receptor as TcdB-10463 but glucosylated the same GTP-binding proteins as TcsL-1522. All three toxins had equal enzymatic potencies but were equally cytotoxic only when microinjected. When applied extracellularly TcdB-1470 and TcdB-10463 were considerably more potent cytotoxins than TcsL-1522. The small GTP-binding protein R-R…
Phylogenetic profiling and cellular analyses of ARL16 reveal roles in traffic of IFT140 and INPP5E
2021
ABSTRACTThe ARF family of regulatory GTPases is ancient, with 16 members predicted to have been present in the last eukaryotic common ancestor. Our phylogenetic profiling of paralogs in diverse species identified four family members whose presence correlates with that of a cilium/flagellum: ARL3, ARL6, ARL13, and ARL16. No prior evidence links ARL16 to cilia or other cell functions, despite its presence throughout eukaryotes. Deletion of ARL16 in MEFs results in decreased ciliogenesis yet increased ciliary length. We also found Arl16 KO in MEFs to alter ciliary protein content, including loss of ARL13B, ARL3, INPP5E, and the IFT-A core component IFT140. Instead, both INPP5E and IFT140 accum…
Role of glycine-82 as a pivot point during the transition from the inactive to the active form of the yeast Ras2 protein
1991
AbstractRas proteins bind either GDP or GTP with high affinity. However, only the GTP-bound form of the yeast Ras2 protein is able to stimulate adenylyl cyclase. To identify amino acid residues that play a role in the conversion from the GDP-bound to the GTP-bound state of Ras proteins, we have searched for single amino acid substitutions that selectively affected the binding of one of the two nucleotides. We have found that the replacement of glycine-82 of the Ras2 protein by serine resulted in an increased rate of dissociation of Gpp(NH)p, a nonhydrolysable analog of GTP, while the GDP dissociation rate was not significantly modified. Glycine-82 resides in a region that is highly conserve…
Impact of NADPH oxidase functional polymorphisms in acute myeloid leukemia induction chemotherapy.
2016
Efficacy and toxicity of anthracycline treatment in acute myeloid leukemia (AML) is mediated by reactive oxygen species (ROS). NADPH oxidase is the major endogenous source of ROS and a key mediator of oxidative cardiac damage. The impact of NADPH oxidase polymorphisms (CYBA:rs4673, NCF4:rs1883112, RAC2:rs13058338) was evaluated in 225 adult de novo AML patients. Variant alleles of NCF4 and RAC2 were related to higher complete remission (P=0.035, P=0.016), and CYBA homozygous variant showed lower overall survival with recessive model (P=0.045). Anthracycline-induced cardiotoxicity was associated to NCF4 homozygous variant (P=0.012) and CYBA heterozygous genotype (P=0.027). Novel associations…
Rho GTPases in human breast tumours: expression and mutation analyses and correlation with clinical parameters
2002
In the present study, we addressed the question of a putative relevance of Rho proteins in tumour progression by analysing their expression on protein and mRNA level in breast tumours. We show that the level of RhoA, RhoB, Rac1 and Cdc42 protein is largely enhanced in all tumour samples analysed (n=15) as compared to normal tissues originating from the same individual. The same is true for 32P-ADP-ribosylation of Rho proteins which is catalysed by Clostridium botulinum exoenzyme C3. Also the amount of Rho-GDI and ERK2 as well as the level of overall 32P-GTP binding acvitity was tumour-specific elevated, yet to a lower extent than Rho proteins. Although the amount of Rho proteins was enhance…
A genome-wide association study of monozygotic twin-pairs suggests a locus related to variability of serum high-density lipoprotein cholesterol
2012
Serum lipid levels have been associated with cardiovascular diseases, metabolic syndrome and type II diabetes (Kannel et al., 1961; Miller & Miller, 1975; Pilia et al., 2006). Variation in lipids levels is highly influenced by heritable factors (Friedlander et al., 1997) and 95 loci have already been associated with levels of high density lipoprotein (HDL) cholesterol, low density lipoprotein (LDL) cholesterol, triglycerides (TG) and total cholesterol (TC) in numerous study samples and replicated in various populations using genome-wide approaches (Aulchenko et al., 2008; Kathiresan et al., 2008; Kooner et al., 2008; Teslovich et al., 2010; Willer et al., 2008). However, the genetic associa…