RESUMO
AIMS: To explore novel microbial endoglucanases with unique properties derived from extreme environments by using metagenomics approach. METHODS AND RESULTS: A Tibetan soil metagenomic library was applied for screening cellulase-active clones by function-based metagenomics. The candidate genes in the active clones were identified through bioinformatic analyses and heterologously expressed using an Escherichia coli system. The recombinant endoglucanases were purified and characterized using enzyme assays to determine their bioactivities, stabilities, substrate specificities, and other enzymatic properties. A novel endoglucanase gene Zfeg1907 was identified, which consisted of a glycoside hydrolase family 44 (GH44) catalytic domain along with a polycystic kidney disease (PKD) domain and a fibronectin type â ¢ (Fn3) domain at the C terminal. Recombinant enzyme ZFEG1907 and its truncated mutant ZFEG1907t (ΔPKDΔFn3) were successfully expressed and purified. The two recombinants exhibited catalytic activities toward carboxymethyl cellulose, konjac glucomannan (KGM), and lichenan. Both enzymes had an optimal temperature of 50°C and an optimal pH value of 5.0. The catalytic activities of both recombinant enzymes were promoted by adding Zn2+ and Ca2+ at the final concentration of 10 mM. The Km value of ZFEG1907 was lower, while the kcat/Km value of ZFEG1907 was higher than those of of ZFEG1907t when using carboxymethyl cellulose, KGM, and lichenan as substrates. Structure prediction of two recombinants revealed that PKD-Fn3 domains consisted of a flexible linker and formed a ß-sandwich structure. CONCLUSIONS: A novel endoglucanase ZFEG1907 contained a GH44 catalytic domain and a PKD-Fn3 domain was characterized. The PKD-Fn3 domains were not indispensable for the activity but contributed to the enzyme binding of the polysaccharide substrates as a carbohydrate-binding module (CBM).
Assuntos
Carboximetilcelulose Sódica , Celulase , Celulase/genética , Metagenômica , Tibet , Escherichia coli/genética , Glicosídeo HidrolasesRESUMO
OBJECTIVE: To explore the expression of fibronectin type â ¢ domain containing 1(FNDC1) protein in lung adenocarcinoma and its prognostic significance. METHODS: The expression of FNDC1 in lung adenocarcinoma was predicted by analysis of data from GEO database and GEPIA, and the results were verified by immunohistochemical staining in 92 pairs of clinical specimens of lung adenocarcinoma and adjacent tissues.We further analyzed the correlation of FNDC1 expression with the clinicopathological features of the patients, and evaluated its prognostic value using Cox survival analysis. RESULTS: Analysis of the data form GEO database and GEPIA showed a significantly higher expression level of FNDC1 in lung adenocarcinoma than in matched normal tissues (P < 0.05).Kaplan-Meier survival analysis suggested that a high expression of FNDC1 protein was associated with a significantly shorter overall survival time of the patients (P < 0.05).Immunohistochemistry of the clinical specimens also showed a significantly higher protein expression of FNDC1 in lung adenocarcinoma tissues than in paired adjacent tissues (P < 0.001).A high expression of FNDC1 protein was significantly correlated with advanced clinical stage, T stage and N stage (P < 0.05).Cox univariate and multivariate regression survival analysis indicated that an increased expression of FNDC1 was an independent risk factor for poor prognosis of the patients with lung adenocarcinoma (P < 0.05). CONCLUSION: FNDC1 protein is highly expressed in patients with lung adenocarcinoma and in closely related with the occurrence, progression and prognosis of the tumor, suggesting the value of FNDC1 protein as a potential biomarker for assessment of the survival and prognosis of patients with lung adenocarcinoma.