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Fibronectin (Fn) is an approximately 450 kDa glycoprotein that consists of 12 type I, 2 type II, and 15–17 type III modules. Fibrillation of Fn is important for tissue reconstitution and wound healing. We previously reported that Clostridium perfringens produces several Fn‐binding proteins (Fbps), two of which, FbpA and FbpB, bind to III1‐C (a fragment of Fn derived from the carboxyl‐terminal two‐thirds of the first‐type III module). Dermatopontin (DPT), a 22 kDa noncollagenous extracellular matrix protein, accelerates normal collagen fibrillation and induces Fn fibrillation. DPT interacts with Fn‐type III12–14 (III12–14), leading to a change in Fn conformation and promoting Fn fibrillation. Here, we investigated the effects of FbpA and FbpB on the binding of Fn and the III12–14 fragment to DPT and on the DPT‐induced Fn fibrillation. Both recombinant FbpA (rFbpA) and recombinant FbpB (rFbpB) significantly inhibited Fn binding to DPT and recombinant III12–14 (rIII12–14) binding, and inhibited DPT‐induced Fn fibrillation. Furthermore, it was found that both rFbpA and rFbpB significantly bound to coated DPT in an enzyme‐linked avidin–biotin complex system, whereas rIII12–14 did not bind to either coated rFbpA or rFbpB. In conclusion, both FbpA and FbpB inhibited DPT‐induced Fn fibrillation via their interaction with DPT. Both FbpA and FbpB released from lysed C. perfringens cells in wounds and/or infected tissue may prevent Fn fibrillation and delay the wound healing process, subsequently exacerbating infection. [ABSTRACT FROM AUTHOR]

Pili in Gram‐positive bacteria are flexible rod proteins associated with the bacterial cell surface, and they play important roles in the initial adhesion to host tissues and colonization. The pilus shaft is formed by the covalent polymerization of major pilins, catalyzed by sortases, a family of cysteine transpeptidases. Here, X‐ray structures of the major pilins from Clostridium perfringens strains 13 and SM101 and of sortase from strain SM101 are presented with biochemical analysis to detect the formation of pili in vivo. The major pilin from strain 13 adopts an elongated structure to form noncovalently linked polymeric chains in the crystal, yielding a practical model of the pilus fiber structure. The major pilin from strain SM101 adopts a novel bent structure and associates to form a left‐handed twist like an antiparallel double helix in the crystal, which is likely to promote bacterial cell–cell interactions. A modeling study showed that pilin with a bent structure interacts favorably with sortase. The major pilin from strain SM101 was considered to be in an equilibrium state between an elongated and a bent structure through dynamic conformational change, which may be involved in pili‐mediated colonization and sortase‐mediated polymerization of pili. [ABSTRACT FROM AUTHOR]

Pili of Gram-positive bacteria are flexible rod proteins covalently attached to the bacterial cell wall, that play important roles in the initial adhesion of bacterial cells to host tissues and bacterial colonization. Pili are formed by the polymerization of major and minor pilins, catalyzed by class C sortase (SrtC), a family of cysteine transpeptidases. The Gram-positive bacterium Clostridium perfringens has a major pilin (CppA), a minor pilin (CppB), and SrtC (CpSrtC). CpSrtC recognizes the C-terminal cell wall sorting signal motifs with five amino acid residues, LPSTG of CppA and LPETG of CppB, for the polymerization of pili. Here, we report biochemical analysis to detect the formation of Clostridium perfringens pili in vivo , and the X-ray structure of a novel intermolecular substrate-enzyme complex of CpSrtC with a sequence of LPST at the C-terminal site. The results showed that CpSrtC has a subsite for substrate-binding to aid polymerization of pili, and that the catalytic site has structural variations, giving insights into the enzyme catalytic reaction mechanism and affinities for the C-terminal cell wall sorting signal motif sequences. The catalytic site shows structural variations involved in the catalytic reaction. [Display omitted] • Pili of Gram-positive bacteria play roles in adhesion to host tissues. • Sortase C, a family of cysteine transpeptidases, catalyzes the formation of pili. • Biochemical and structural analyses of C. perfringens sortase C were performed. • Sortase C has a subsite for substrate-binding to aid polymerization of pili. [ABSTRACT FROM AUTHOR]

Alcohol hangover is an unpleasant state caused by acetaldehyde, which is produced by partial oxidation of ethanol. Treating hangover is important from the viewpoint of preventing excessive drinking. In the present study, we attempted to produce mouse model of alcohol hangover by intraperitoneal pretreatment with cyanamide at 12.5 mg/kg followed by oral ethanol at 1.6 g/kg. The mice showed decrease of spontaneous locomotor activity and food intake. Thus, it is suggested that the hangover model was successively established by co-administration of cyanamide and ethanol. Solmack, a product based on herbal medicine for stomach anda pproved as medical drug, recovered decrease of spontaneous locomotor activity and tended to recover decrease of food intake in the.hangover model mice. Other refreshing drinks did not show such effects, though they contain herbal medicine ingredients to some extent. Our model in mice might be useful to detect effective treatment for alcohol hangover.