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Various Cellular Activities (various + cellular_activity)
Selected AbstractsCommunication between E,54, promoter DNA and the conserved threonine residue in the GAFTGA motif of the PspF ,54 -dependent activator during transcription activationMOLECULAR MICROBIOLOGY, Issue 2 2004Patricia Bordes Summary Conversion of E,54 closed promoter complexes to open promoter complexes requires specialized activators which are members of the AAA (ATPases Associated with various cellular Activities) protein family. The ATP binding and hydrolysis activity of E,54 activators is used in an energy coupling reaction to remodel the E,54 closed promoter complex and to overcome the ,54 -imposed block on open complex formation. The remodelling target for the AAA activator within the E,54 closed complex includes a complex interface contributed to by Region I of ,54, core RNA polymerase and a promoter DNA fork junction structure, comprising the E,54 regulatory centre. One ,54 binding surface on E,54 activators is a conserved sequence known as the GAFTGA motif. Here, we present a detailed characterization of the interaction between Region I of ,54 and the Escherichia coli AAA ,54 activator Phage shock protein F. Using E,54 promoter complexes that mimic different conformations adopted by the DNA during open complex formation, we investigated the contribution of the conserved threonine residue in the GAFTGA motif to transcription activation. Our results suggest that the organization of the E,54 regulatory centre, and in particular the conformation adopted by the ,54 Region I and the DNA fork junction structure during open complex formation, is communicated to the AAA activator via the conserved T residue of the GAFTGA motif. [source] Human spastin has multiple microtubule-related functionsJOURNAL OF NEUROCHEMISTRY, Issue 5 2005Sara Salinas Abstract Hereditary spastic paraplegias (HSPs) are neurodegenerative diseases caused by mutations in more than 20 genes, which lead to progressive spasticity and weakness of the lower limbs. The most frequently mutated gene causing autosomal dominant HSP is SPG4, which encodes spastin, a protein that belongs to the family of ATPases associated with various cellular activities (AAAs). A number of studies have suggested that spastin regulates microtubule dynamics. We have studied the ATPase activity of recombinant human spastin and examined the effect of taxol-stabilized microtubules on this activity. We used spastin translated from the second ATG and provide evidence that this is the physiologically relevant form. We showed that microtubules enhance the ATPase activity of the protein, a property also described for katanin, an AAA of the same spastin subgroup. Furthermore, we demonstrated that human spastin has a microtubule-destabilizing activity and can bundle microtubules in vitro, providing new insights into the molecular pathogenesis of HSP. [source] Characterization of a Mycobacterium tuberculosis proteasomal ATPase homologueMOLECULAR MICROBIOLOGY, Issue 2 2005K. Heran Darwin Summary A screen for Mycobacterium tuberculosis (Mtb) mutants sensitive to reactive nitrogen intermediates identified transposon insertions in the presumptive proteasomal ATPase gene mpa (mycobacterium proteasome ATPase; Rv2115c). mpa mutants are attenuated in both wild type and nitric oxide synthase 2 deficient mice. In this work, we show that attenuation of mpa mutants is severe, and that Mpa is an ATPase associated with various cellular activities (AAA) ATPase that forms hexameric rings resembling the eukaryotic complex p97/valosin-containing protein (VCP). Point mutations in the conserved Walker box ATPase motifs of Mpa greatly reduced or abolished ATPase activity in vitro and abrogated protection of Mtb against acidified nitrite. A mutant Mpa protein missing only its last two amino acids retained ATPase activity, yet failed to protect Mtb against nitrite. The corresponding strain was attenuated in mice. Thus, Mpa is an ATPase whose enzymatic activity is necessary but not sufficient to protect against reactive nitrogen intermediates. [source] Cloning, expression, purification and preliminary X-ray crystallographic studies of Escherichia coli Hsp100 nucleotide-binding domain 2 (NBD2)ACTA CRYSTALLOGRAPHICA SECTION D, Issue 6-2 2002Jingzhi Li Escherichia coli Hsp100 ClpB has been identified recently as playing critical roles in multi-chaperone systems. ClpB binds and disaggregates denatured polypeptides by employing ATP hydrolysis and allows other molecular chaperones such as Hsp70 DnaK and Hsp40 DnaJ to refold the non-native polypeptides. ClpB contains two nucleotide-binding domains (NBD1 and NBD2) in its primary sequence. Walker A and Walker B motifs exist in both nucleotide-binding domains. Therefore, ClpB belongs to the large ATPase family known as ATPase associated with various cellular activities (AAA). The mechanisms by which NBD1 and NBD2 function to support the ClpB molecular-chaperone activity are currently unknown. To investigate how NBD2 participates in ClpB function to disaggregate denatured proteins, ClpB NBD2 has been cloned and crystallized. The ClpB NBD2 crystals diffract X-rays to 2.5,Å using synchrotron X-ray sources. The crystals belong to space group P212121, with unit-cell parameters a = 99.57, b = 149.34, c = 164.69,Å. [source] Purification, crystallization and preliminary X-ray diffraction analysis of disease-related mutants of p97ACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 11 2009Wai-Kwan Tang The human type II AAA+ protein p97 participates in various cellular activities, presumably through its involvement in the ubiquitin,proteasome degradation pathway. Mutations in p97 have been implicated in patients with inclusion-body myopathy associated with Paget's disease of the bone and frontotemporal dementia (IBMPFD). In this work, three mutant p97 N-D1 fragments, R86A, R95G and R155H, were crystallized in the presence of ATP,S with PEG 3350 as a main precipitant, yielding two different crystal forms. The R155H mutant crystal belonged to space group R3, with unit-cell parameters in the hexagonal setting of a = b = 134.2, c = 182.9,Å, and was merohedrally twinned, with an estimated twin fraction of 0.34. The crystals of the R86A and R95G mutants belonged to space group P1, with similar unit-cell parameters of a = 90.89, b = 102.6, c = 107.2,Å, , = 97.5, , = 90.6, , = 91.5° and a = 92.76, b = 103.7, c = 107.7,Å, , = 97.7, , = 91.9, , = 89.7°, respectively. [source] Crystallographic characterization of the N-terminal domain of a plant NADPH oxidaseACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 9 2008Takashi Oda Respiratory burst oxidase homologue (Rboh), which is found in the plasma membrane, is a generator of reactive oxygen species (ROS) in plants. Many studies have indicated that the ROS produced by Rboh play critical roles in various cellular activities, including plant defence against pathogens. Crystals of the N-terminal domain of Oryza sativa RbohB (OsRbohB) have been obtained. The crystals belonged to space group P212121, with unit-cell parameters a = 60.4, b = 72.2, c = 118.9,Å. An intensity data set was collected to 2.4,Å resolution. [source] | |||||||||||||