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Ling Wang,Xuemei Zhang,Guangying Wu,Yuhong Qi,Jinghui Zhang,Jing Yang,Hong Wang,Wenchun Xu 한국미생물학회 2020 The journal of microbiology Vol.58 No.4
Streptococcus pneumoniae is a Gram-positive pathogen with high morbidity and mortality globally but some of its pathogenesis remains unknown. Previous research has provided evidence that aminopeptidase N (PepN) is most likely a virulence factor of S. pneumoniae. However, its role in S. pneumoniae virulence and its interaction with the host remains to be confirmed. We generated a pepN gene deficient mutant strain and found that its virulence for mice was significantly attenuated as were in vitro adhesion and invasion of host cells. The PepN protein could induce a strong innate immune response in vivo and in vitro and induced secretion of IL-6 and TNF-α by primary peritoneal macrophages via the rapid phosphorylation of MAPK and PI3K/AKT signaling pathways and this was confirmed using specific pathway inhibitors. In conclusion, PepN is a novel virulence factor that is essential for the virulence of S. pneumoniae and induces host innate immunity via MAPK and PI3K/AKT signaling.
Xuying Nan,Lili Sun,Xinming Song,Mingshu Wu,Guangying Chen,Yuhua Yao 한국섬유공학회 2019 Fibers and polymers Vol.20 No.8
A water-soluble silk peptide (SP) was fractioned to a series of SP fractions with different molecular weight. Theantioxidant activity of these fractions was investigated by the ABTS and DPPH assays, and the co-initiating ability of eachfraction in type II photoinitiator was evaluated in photopolymerization of acrylamide, using camphorquinone as thesensitizer. Gel permeation chromatograph was used to investigate molecular weight distributions of SP fractions. The resultsshowed that with the increase of the proportion of the component with molecular weight of about 200 in SP fractions,antioxidant activity and co-initiation ability became poor. Four essential amino acids, Ala, Gly, Ser and Tyr of SP and theirrespective pentapeptides were also assessed for these two functions. Among them, pentatyrosine exhibited the most excellentperformance in two functions, which might be ascribed to its excellent electron/hydrogen donation capability. Andpentaglycine had good behavior in these two functions, suggesting that the polypeptide chain was responsible for electron/hydrogen donation. By 1H NMR analysis, it was speculated that the photoinitiation active center was located on themethylene group of pentaglycine. The electron/hydrogen donor of SP is the inherent reason for antioxidant function andphotoinitiation performance of SP.