Weak Interactions between Salmonella enterica FlhB and Other Flagellar Export Apparatus Proteins Govern Type III Secretion Dynamics

The bacterial flagellum contains its own type III secretion apparatus that coordinates protein export with assembly at the distal end. While many interactions among export apparatus proteins have been reported, few have been examined with respect to the differential affinities and dynamic relationships that must govern the mechanism of export. FlhB, an integral membrane protein, plays critical roles in both export and the substrate specificity switching that occurs upon hook completion. Reported herein is the quantitative characterization of interactions between the cytoplasmic domain of FlhB (FlhBC) and other export apparatus proteins including FliK, FlhAC and FliI. FliK and FlhAC bound with micromolar affinity. KD for FliI binding in the absence of ATP was 84 nM. ATP-induced oligomerization of FliI induced kinetic changes, stimulating fast-on, fast-off binding and lowering affinity. Full length FlhB purified under solubilizing, nondenaturing conditions formed a stable dimer via its transmembrane domain and stably bound FliH. Together, the present results support the previously hypothesized central role of FlhB and elucidate the dynamics of protein-protein interactions in type III secretion

実験的閉塞性黄疸における脳組織の変化に関する研究

取得学位 : 博士（医学）, 学位授与番号 : 医博乙第1119号, 学位授与年月日：平成3年2月6日,学位授与年：199

13C-NMR Spectroscopic Study on Chemical Species in Piperazine−Amine−CO2−H2O System before and after Heating

AbstractChemical reactions associated with the absorption of CO2 into aqueous solutions of blends of piperazine (PZ) with N- methyldiethanolamine (MDEA), etc. were studied by 13C-NMR spectroscopy. The coexistence of PZ and MDEA enhanced the initial apparent rate of HCO3−/CO2−3 formation. This result can be explained by considering that PZ−monocarbamate rapidly formed works as an organocatalyst in the formation reaction of HCO−3. Concentration changes of chemical species in CO2-absorbed aqueous amine solutions upon heating (80°C, 30min) were studied by 13C-NMR spectroscopy. Carbon dioxide regeneration originates mainly from HCO3−/CO3, and not form carbamate and carbonate

Development of incident X-ray flux monitor for coherent X-ray diffraction microscopy

An incident X-ray flux monitor for coherent X-ray diffraction microscopy was developed. The intensities of x-rays passing through the sample were measured using an X-ray photodiode, with the simultaneous measurement of the X-ray diffraction intensities of the sample. As a result of the normalization of the X-ray diffraction intensities by the incident X-ray flux determined from the monitor, the fluctuation of the speckle intensities was successfully suppressed. © 2009 IOP Publishing Ltd.Takahashi Y., Kubo H., Furukawa H., et al. Development of incident X-ray flux monitor for coherent X-ray diffraction microscopy. Journal of Physics: Conference Series, 186, , 012060. https://doi.org/10.1088/1742-6596/186/1/012060.9TH INTERNATIONAL CONFERENCE ON X-RAY MICROSCOPY 21–25 July 2008, Zürich, Switzerlan

An experimental procedure for precise evaluation of electron density distribution of a nanostructured material by coherent x-ray diffraction microscopy

We developed a coherent x-ray diffraction microscopy (CXDM) system that enables us to precisely evaluate the electron density of an isolated sample. This system enables us to determine the dose per surface unit of x rays illuminated onto an isolated sample by combining incident x-ray intensity monitoring and the CXDM of a reference sample. By using this system, we determined the dose of x rays illuminated onto a nanostructured island fabricated by focused-ion-beam chemical vapor deposition and derived the electron density distribution of such a nanostructured island. A projection image of the nanostructured island with a spatial resolution of 24.1 nm and a contrast resolution higher than 2.3× 107 electrons/pixel was successfully reconstructed. © 2010 American Institute of Physics.Yukio Takahashi, Hideto Kubo, Yoshinori Nishino, Hayato Furukawa, Ryosuke Tsutsumi, Kazuto Yamauchi, Tetsuya Ishikawa, and Eiichiro Matsubara, "An experimental procedure for precise evaluation of electron density distribution of a nanostructured material by coherent x-ray diffraction microscopy", Review of Scientific Instruments 81(3), 033707 (2010) https://doi.org/10.1063/1.3361265