scholarly journals A novel antibacterial agent derived from the C-terminal domain of Streptococcus mutans GTP-binding protein

2000 ◽  
Vol 46 (1) ◽  
pp. 95-99 ◽  
Author(s):  
S.-H. Ohk
Keyword(s):  
Streptococcus Mutans ◽  
Antibacterial Agent ◽  
Binding Protein ◽  
Gtp Binding Protein ◽  
Terminal Domain ◽  
Gtp Binding

scholarly journals Stress-Induced Membrane Association of the Streptococcus mutans GTP-Binding Protein, an Essential G Protein, and Investigation of Its Physiological Role by Utilizing an Antisense RNA Strategy

1999 ◽  
Vol 67 (9) ◽  
pp. 4510-4516 ◽  
Author(s):  
Didi Baev ◽  
Reg England ◽  
Howard K. Kuramitsu
Keyword(s):  
Elevated Temperature ◽  
Stress Response ◽  
Streptococcus Mutans ◽  
Antisense Rna ◽  
Binding Protein ◽  
Physiological Role ◽  
Acidic Ph ◽  
Gtp Binding Protein ◽  
Gtp Binding

ABSTRACT SGP (for Streptococcus GTP-binding protein) is aStreptococcus mutans essential GTPase which has significant sequence identity to the previously identified Escherichia coli Era protein and to numerous other prokaryotic GTPase proteins of unknown function. Recent studies in our laboratory have addressed the possible role of SGP in the stress response of the oral pathogen S. mutans. Here we report that during growth in the early stationary phase, and in response to elevated temperatures or acidic pH, the distribution of SGP between the cytoplasm and the membranes of S. mutans cells varies. Immunoblot analysis of soluble and membrane protein fractions collected from the mid-log and early stationary growth phases of bacterial populations grown at normal temperature (37°C) and at the elevated temperature of 43°C, or at acidic pH, demonstrated that the total amount of SGP increased with the age of the bacterial culture, elevated temperature, or acidic pH. Furthermore, it was established that a substantial amount of SGP is associated with the membrane fraction under stress conditions. In order to investigate the physiological role of SGP, we constructed anS. mutans strain capable of chromosomalsgp antisense RNA expression, which interferes with the normal information processing of the sgp gene. Utilizing this strain, we determined conditions whereby the streptococcal cells can be depleted of SGP, thus avoiding the problem of constructing a conditional lethal system. From the results of measurements of the nucleotide pools extracted from the antisense strain and its isogenic counterpart, we propose that one of the physiological roles of SGP is regulation and modulation of the GTP/GDP ratio under different growth conditions. Moreover, we observed that in SGP-depleted cells the levels of glucan-binding protein A (GbpA) substantially increased, suggesting that GbpA may have stress response-related physiological functions. Finally, the potential applications of the antisense RNA approach that we employed are discussed.

Small GTP-binding Protein RalA Associates with Weibel-Palade Bodies in Endothelial Cells

1999 ◽  
Vol 82 (09) ◽  
pp. 1177-1181 ◽  
Author(s):  
Hubert de Leeuw ◽  
Pauline Wijers-Koster ◽  
Jan van Mourik ◽  
Jan Voorberg
Keyword(s):  
Endothelial Cells ◽  
Binding Proteins ◽  
Binding Protein ◽  
Control Release ◽  
Small Gtpase ◽  
Gtp Binding Protein ◽  
Two Dimensional Gel Electrophoresis ◽  
Gtp Binding Proteins ◽  
Dense Granules ◽  
Gtp Binding

SummaryIn endothelial cells von Willebrand factor (vWF) and P-selectin are stored in dense granules, so-called Weibel-Palade bodies. Upon stimulation of endothelial cells with a variety of agents including thrombin, these organelles fuse with the plasma membrane and release their content. Small GTP-binding proteins have been shown to control release from intracellular storage pools in a number of cells. In this study we have investigated whether small GTP-binding proteins are associated with Weibel-Palade bodies. We isolated Weibel-Palade bodies by centrifugation on two consecutive density gradients of Percoll. The dense fraction in which these subcellular organelles were highly enriched, was analysed by SDS-PAGE followed by GTP overlay. A distinct band with an apparent molecular weight of 28,000 was observed. Two-dimensional gel electrophoresis followed by GTP overlay revealed the presence of a single small GTP-binding protein with an isoelectric point of 7.1. A monoclonal antibody directed against RalA showed reactivity with the small GTP-binding protein present in subcellular fractions that contain Weibel-Palade bodies. The small GTPase RalA was previously identified on dense granules of platelets and on synaptic vesicles in nerve terminals. Our observations suggest that RalA serves a role in regulated exocytosis of Weibel-Palade bodies in endothelial cells.

Rap1b Association with the Platelet Cytoskeleton Occurs in the Absence of Glycoproteins IIb/IIIa

1998 ◽  
Vol 79 (04) ◽  
pp. 832-836 ◽  
Author(s):  
Thomas Fischer ◽  
Christina Duffy ◽  
Gilbert White
Keyword(s):  
Molecular Weight ◽  
Divalent Cation ◽  
Binding Proteins ◽  
Binding Protein ◽  
Platelet Membrane ◽  
Low Molecular Weight ◽  
Membrane Glycoproteins ◽  
Gtp Binding Protein ◽  
Gtp Binding Proteins ◽  
Gtp Binding

SummaryPlatelet membrane glycoproteins (GP) IIb/IIIa and rap1b, a 21 kDa GTP binding protein, associate with the triton-insoluble, activation-dependent platelet cytoskeleton with similar rates and divalent cation requirement. To examine the possibility that GPIIb/IIIa was required for rap1b association with the cytoskeleton, experiments were performed to determine if the two proteins were linked under various conditions. Chromatography of lysates from resting platelets on Sephacryl S-300 showed that GPIIb/IIIa and rap1b were well separated and distinct proteins. Immunoprecipitation of GPIIb/IIIa from lysates of resting platelets did not produce rap1b or other low molecular weight GTP binding proteins and immunoprecipitation of rap1b from lysates of resting platelets did not produce GPIIb/IIIa. Finally, rap1b was associated with the activation-dependent cytoskeleton of platelets from a patient with Glanzmann’s thrombasthenia who lacks surface expressed glycoproteins IIb and IIIa. Based on these findings, we conclude that no association between GPIIb/IIIa and rap1b is found in resting platelets and that rap1b association with the activation-dependent cytoskeleton is at least partly independent of GPIIb/IIIa.

Characterization and Functional Analysis of a Small GTP-binding Protein AtRAB Interacting with H+-pyrophosphatase AVP1 inArabidopsis thaliana

2014 ◽  
Vol 40 (10) ◽  
pp. 1756
Author(s):  
Rong-Bang LIU ◽  
Ming CHEN ◽  
Meng-Meng GUO ◽  
Qing-Lin SI ◽  
Shi-Qing GAO ◽  
...  
Keyword(s):  
Functional Analysis ◽  
Binding Protein ◽  
Gtp Binding Protein ◽  
Gtp Binding

Crystal Structure of the GTP-binding Protein Obg from Thermus thermophilus HB8

2004 ◽  
Vol 337 (3) ◽  
pp. 761-770 ◽  
Author(s):  
Mutsuko Kukimoto-Niino ◽  
Kazutaka Murayama ◽  
Mio Inoue ◽  
Takaho Terada ◽  
Jeremy R.H. Tame ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Binding Protein ◽  
Thermus Thermophilus ◽  
Gtp Binding Protein ◽  
Thermus Thermophilus Hb8 ◽  
Gtp Binding
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