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Simultaneous data acquisition in time-sharing (TS) multi-dimensional NMR experiments has been shown an effective means to reduce experimental time, and thus to accelerate structure determination of proteins. This has been accomplished by spin evolution time-sharing of the X and Y heteronuclei, such as 15N and 13C, in one of the time dimensions. In this work, we report a new 3D TS experiment, which allows simultaneous 13C and 15N spin labeling coherence in both t
1 and t
2 dimensions to give four NOESY spectra in a single 3D experiment. These spectra represent total NOE correlations between 1HN and 1HC resonances. This strategy of double time-sharing (2TS) results in an overall four-fold reduction in experimental time compared with its conventional counterpart. This 3D 2TS CN-CN-H HSQC-NOESY-HSQC pulse sequence also demonstrates improvements in water suppression, 15N spectral resolution and sensitivity, which were developed based on 2D TS CN-H HSQC and 3D TS H-CN-H NOESY-HSQC experiments. Combining the 3D TS and the 3D 2TS NOESY experiments, NOE assignment ambiguities and errors are considerably reduced. These results will be useful for rapid protein structure determination to complement the effort of discerning the functions of diverse genomic proteins. 相似文献
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Cort JR Yee A Edwards AM Arrowsmith CH Kennedy MA 《Journal of structural and functional genomics》2000,1(1):15-25
The solution structure of MTH1175, a 124-residue protein from the archaeon Methanobacterium thermoautotrophicum has been determined
by NMR spectroscopy. MTH1175 is part of a family of conserved hypothetical proteins (COG1433) with unknown functions which
contains multiple paralogs from all complete archaeal genomes and the archaeal gene-rich bacterium Thermotoga maritima. Sequence
similarity indicates this protein family may be related to the nitrogen fixation proteins NifB and NifX. MTH1175 adopts an
α/β topology with a single mixed β-sheet, and contains two flexible loops and an unstructured C-terminal tail. The fold resembles
that of Ribonuclease H and similar proteins, but differs from these in several respects, and is not likely to have a nuclease
activity.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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Li PX Wong J Ayed A Ngo D Brade AM Arrowsmith C Austin RC Klamut HJ 《The Journal of biological chemistry》2000,275(26):20127-20135
The p53 tumor suppressor gene and members of the transforming growth factor-beta (TGF-beta) superfamily play central roles in signaling cell cycle arrest and apoptosis (programmed cell death) in normal development and differentiation, as well as in carcinogenesis. Here we describe a distantly related member of the TGF-beta superfamily, designated placental TGF-beta (PTGF-beta), that is up-regulated in response to both p53-dependent and -independent apoptotic signaling events arising from DNA damage in human breast cancer cells. PTGF-beta is normally expressed in placenta and at lower levels in kidney, lung, pancreas, and muscle but could not be detected in any tumor cell line studied. The PTGF-beta promoter is activated by p53 and contains two p53 binding site motifs. Functional studies demonstrated that one of these p53 binding sites is essential for p53-mediated PTGF-beta promoter induction and specifically binds recombinant p53 in gel mobility shift assays. PTGF-beta overexpression from a recombinant adenoviral vector (AdPTGF-beta) led to an 80% reduction in MDA-MB-468 breast cancer cell viability and a 50-60% reduction in other human breast cancer cell lines studied, including MCF-7 cells, which are resistant to growth inhibition by recombinant wild-type p53. Like p53, PTGF-beta overexpression was seen to induce both G(1) cell cycle arrest and apoptosis in breast tumor cells. These results provide the first evidence for a direct functional link between p53 and the TGF-beta superfamily and implicate PTGF-beta as an important intercellular mediator of p53 function and the cytostatic effects of radiation and chemotherapeutic cancer agents. 相似文献
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Relative importance of osmotic-stress and ion-specific effects on ABA-mediated inhibition of leaf expansion growth in Phaseolus vulgaris 总被引:2,自引:1,他引:1
The osmotic and ion-specific components of salt-induced inhibition of leaf expansion growth were investigated in beans grown from 12 h to several days in either NaCl-containing solution cultures, an isosmotic concentrated macronutrient solution, or a vermiculite–compost mixture with low Na+ but high Cl– availability. Inhibition of leaf expansion and leaf ABA increase was more intense in the NaCl than in the isosmotic macronutrient treatment. Root Na+ was highly correlated to inhibition of leaf expansion and leaf or xylem sap ABA. When Na+ was sequestered in soil, salinized plants showed no reduction in leaf expansion or ABA increase, regardless of the presence of high leaf Cl– concentrations. Stomatal conductance exhibited an exponential relationship with the reciprocal value of xylem sap ABA. Our results indicate that an ion-specific effect caused by Na+ in roots may account for an ABA-mediated reponse of both stomatal closure and leaf expansion inhibition. 相似文献
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