Flagellar type III secretion systems (T3SS) contain an essential cytoplasmic-ring (C-ring) largely composed of two proteins FliM and FliN, whereas an analogous substructure for the closely related non-flagellar (NF) T3SS has not been observed in situ. We show that the spa33 gene encoding the putative NF-T3SS C-ring component in Shigella flexneri is alternatively translated to produce both full-length (Spa33-FL) and a short variant (Spa33-C), with both required for secretion. They associate in a 1:2 complex (Spa33-FL/C2) that further oligomerises into elongated arrays in vitro. The structure of Spa33-C2 and identification of an unexpected intramolecular pseudodimer in Spa33-FL reveal a molecular model for their higher order assembly within NF-T3SS. Spa33-FL and Spa33-C are identified as functional counterparts of a FliM-FliN fusion and free FliN respectively. Furthermore, we show that Thermotoga maritima FliM and FliN form a 1:3 complex structurally equivalent to Spa33-FL/C2 , allowing us to propose a unified model for C-ring assembly by NF-T3SS and flagellar-T3SS.
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http://dx.doi.org/10.1111/mmi.13267 | DOI Listing |
Int J Biol Macromol
December 2024
Key Laboratory of Forest Food Resources Utilization of Heilongjiang Province, Harbin 150040, China; College of Life Sciences, Northeast Forestry University, Harbin 150040, China. Electronic address:
The present study investigated the covalent binding behavior of the flavonoids, catechin, eriodictyol, luteolin and quercetin with β-lactoglobulin (βlg). Since the four flavonoids possess the identical A- and B-ring structures, effects of the C-rings on the properties of flavonoids and the corresponding semiquinones are revealed. Experimental methods including DLS and CD spectra indicated that with quercetin at room temperature did not induce aggregation of βlg, whilst binding with the other three flavonoids resulted in aggregation of βlg.
View Article and Find Full Text PDFJ Pharm Biomed Anal
December 2024
Guang'an Men Hospital, China Academy of Chinese Medical Sciences, Beijing 100010, China. Electronic address:
Daidzin, as one of isoflavone glycosides, has been reported to have multiple activities with few absorbed into body. However, the metabolic behavior of daidzin by intestinal flora has not been researched, that this defect severely constrains its applications. In this study, daidzin and its metabolites were qualitatively and quantitatively analyzed by HPLC and ultra-high performance liquid chromatography coupled to high-resolution mass spectrometry (UHPLC-HRMS) in the fermentation system for daidzin and fecal bacteria.
View Article and Find Full Text PDFBioorg Med Chem
December 2024
Department of Internal Medicine, Macon & Joan Brock Virginia Health Sciences at Old Dominion University, Norfolk, VA 23507, United States. Electronic address:
The boronic acid group plays an important role in drug discovery. Following our discovery of a boronic acid analog of combretastatin A-4 (CA-4), a series of analogs featuring a boronic acid group on the C phenyl ring of CA-4 was synthesized and evaluated for cytotoxicity, as well as for their ability to inhibit tubulin polymerization, inhibit the binding of [H]colchicine to tubulin and cause depolymerization of cellular microtubules. Modifications on the C ring of CA-4, either eliminating the methoxy group or replacing the C phenyl ring with a pyridine ring, resulted in a reduced potency for inhibiting tubulin polymerization, colchicine binding and cytotoxic activities as compared to CA-4.
View Article and Find Full Text PDFCommun Biol
October 2024
Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.
Zoospores of the filamentous actinomycete Actinoplanes missouriensis swim vigorously using flagella and stop swimming to initiate germination in response to nutrient exposure. However, the molecular mechanisms underlying swimming cessation remain unknown. A protein (FtgA) of unknown function encoded by a chemotaxis gene cluster (che cluster-1) was found to be required for flagellar rotation arrest; the zoospores of ftgA-knockout mutants kept swimming awkwardly after germination.
View Article and Find Full Text PDFJ Bacteriol
November 2024
Department of Bacteriology, University of Wisconsin-Madison, Madison, Wisconsin, USA.
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