Architecture of the Bacterial Flagellar Distal Rod and Hook of Salmonella

The bacterial flagellum is a large molecular complex composed of thousands of protein subunits for motility. The filamentous part of the flagellum, which is called the axial structure, consists of the filament, the hook, and the rods, with other minor components-the cap protein and the hook associated proteins. They share a common basic architecture of subunit arrangement, but each part shows quite distinct mechanical properties to achieve its specific function. The distal rod and the hook are helical assemblies of a single protein, FlgG and FlgE, respectively. They show a significant sequence similarity but have distinct mechanical characteristics. The rod is a rigid, straight cylinder, whereas the hook is a curved tube with high bending flexibility. Here, we report a structural model of the rod constructed by using the crystal structure of a core fragment of FlgG with a density map obtained previously by electron cryomicroscopy. Our structural model suggests that a segment called L-stretch plays a key role in achieving the distinct mechanical properties of the rod using a structurally similar component protein to that of the hook

Pyridoxal in the Cerebrospinal Fluid May Be a Better Indicator of Vitamin B6–dependent Epilepsy Than Pyridoxal 5′-Phosphate

Background We aimed to demonstrate the biochemical characteristics of vitamin B6–dependent epilepsy, with a particular focus on pyridoxal 5′-phosphate and pyridoxal in the cerebrospinal fluid. Methods Using our laboratory database, we identified patients with vitamin B6–dependent epilepsy and extracted their data on the concentrations of pyridoxal 5′-phosphate, pyridoxal, pipecolic acid, α-aminoadipic semialdehyde, and monoamine neurotransmitters. We compared the biochemical characteristics of these patients with those of other epilepsy patients with low pyridoxal 5′-phosphate concentrations. Results We identified seven patients with pyridoxine-dependent epilepsy caused by an ALDH7A1 gene abnormality, two patients with pyridoxal 5′-phosphate homeostasis protein deficiency, and 28 patients with other epilepsies with low cerebrospinal fluid pyridoxal 5′-phosphate concentrations. Cerebrospinal fluid pyridoxal and pyridoxal 5′-phosphate concentrations were low in patients with vitamin B6–dependent epilepsy but cerebrospinal fluid pyridoxal concentrations were not reduced in most patients with other epilepsies with low cerebrospinal fluid pyridoxal 5′-phosphate concentrations. Increase in 3-O-methyldopa and 5-hydroxytryptophan was demonstrated in some patients with vitamin B6–dependent epilepsy, suggestive of pyridoxal 5′-phosphate deficiency in the brain. Conclusions Low cerebrospinal fluid pyridoxal concentrations may be a better indicator of pyridoxal 5′-phosphate deficiency in the brain in vitamin B6–dependent epilepsy than low cerebrospinal fluid pyridoxal 5′-phosphate concentrations. This finding is especially helpful in individuals with suspected pyridoxal 5′-phosphate homeostasis protein deficiency, which does not have known biomarkers

1)Critical Behaviors Near the Antiferroelectric Phase Transition Temperature of NaNO_2

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ELEMENTAL ANALYSIS OF ATMOSPHERIC PARTICLES COLLECTED ON POLYTERAFLUOROETYLENE (PTFE) FILTER USING IN-AIR HELIUM ION INDUCED X-RAY EMISSION METHOD

In order to confirm the availability of an in-air Helium ion induced X-ray emission method for multi-elemental analysis of polytetrafluoroetylene (PEFE) filter sample containing atmospheric particles, NIST urban particulate matter (SRM 1648) collected on PTFE filter using a special small chamber was analyzed by an in-air PIXE method with Helium ions and proton beam, In addition, we analyzed 10 elements, mixing a standard solution with different concentrations to confirm, detection sensitivity of characteristic X-ray peaks, As a result, it is suggested that 1) elements that are lighter than Zn and Pb can be satisfactorily measured using the in-air Helium ion induced X-ray emission method if the amount contained in the filter sample is at least 0.1 mg/L, i.e., 15ng/cm2 , 2) the in-air Helium ion induced X-ray emission method is useful as a method for quantitatively analyzing the light elements such as Mg, Al, Si, S and Cl that are important for identifying the behavior and characteristics of atmospheric particles from the PTFE filter sample containing atmospheric particles, and 3) in the case of the PTFE filter sample containing atmospheric particles, it is possible to measure elements from Mg to Pb by means of analysis using Helium ions an protons

Crystallization and preliminary X-ray analysis of the C-terminal cytoplasmic domain of FlhA, a membrane-protein subunit of the bacterial flagellar type III protein-export apparatus

Crystals of the cytoplasmic domain of FlhA, a membrane-protein component of the bacterial flagellar type III protein-export apparatus from Salmonella, have been obtained and characterized by X-ray diffraction

Role of the C-Terminal Cytoplasmic Domain of FlhA in Bacterial Flagellar Type III Protein Export▿

For construction of the bacterial flagellum, many of the flagellar proteins are exported into the central channel of the flagellar structure by the flagellar type III protein export apparatus. FlhA and FlhB, which are integral membrane proteins of the export apparatus, form a docking platform for the soluble components of the export apparatus, FliH, FliI, and FliJ. The C-terminal cytoplasmic domain of FlhA (FlhAC) is required for protein export, but it is not clear how it works. Here, we analyzed a temperature-sensitive Salmonella enterica mutant, the flhA(G368C) mutant, which has a mutation in the sequence encoding FlhAC. The G368C mutation did not eliminate the interactions with FliH, FliI, FliJ, and the C-terminal cytoplasmic domain of FlhB, suggesting that the mutation blocks the export process after the FliH-FliI-FliJ-export substrate complex binds to the FlhA-FlhB platform. Limited proteolysis showed that FlhAC consists of at least three subdomains, a flexible linker, FlhACN, and FlhACC, and that FlhACN becomes sensitive to proteolysis by the G368C mutation. Intragenic suppressor mutations were identified in these subdomains and restored flagellar protein export to a considerable degree. However, none of these suppressor mutations suppressed the protease sensitivity. We suggest that FlhAC not only forms part of the docking platform for the FliH-FliI-FliJ-export substrate complex but also is directly involved in the translocation of the export substrate into the central channel of the growing flagellar structure