An endoglucanase, GsCelA, from Geobacilus sp. undergoes an intriguing self- truncation process for enhancing activity and thermostability

An endoglucanase, GsCelA, was isolated and cloned from a thermophilic Geobacillus sp. 70PC53 grown in a rice straw compost in southern Taiwan. It was observed that highly purified GsCelA was able to self-truncate, removing a segment of 53 amino acid residues from its C-terminus. The purified GsCelA does not possess any protease activity and this self-truncation process is insensitive to standard protease inhibitors except EDTA and EGTA. This unique self-truncation process takes place at a temperature higher than 10C with an optimal pH between 6-7, and can be further enhanced with certain divalent ions such as Ca+2 and Mg+2. Crystal structure of GsCelA has a typical TIM-barrel configuration with 8 alpha-helices and 8 beta-strands, but with the presence of a divalent ion. Mutations of amino acids residues surrounding this metal ion do not affect the self-truncation process, but some of these mutants have enhanced enzymatic activities. Mutation of the cleavage site between K315 and G316 does not affect the self-truncation process. However, a deletion of ten amino acids near the cleavage site, i.e. from amino acid 310 to 320, slows down the truncation process but does not block it, and a truncated form around 315 amino acids in length eventually appears. This intriguing observation indicates that the self-truncation process is not site specific, but capable of measuring 315 amino acids from the N-terminus as the cleavage site. This self-truncation process also occurs in the native host of this enzyme, Geobacillus sp. 70PC53, with almost all secreted form of this enzyme being self-truncated. The 53 amino-acid-long C-terminal segment removed by this self-truncation process has binding affinity toward both crystal and amorphous cellulose as well as the s cell walls, yet its sequence bears no apparent homology to any known carbohydrate binding motifs. Various other mutation analyses and the structure-based recombination process, SCHEMA, have been carried out, and both the activity and thermostabilty of this enzyme are further improved. The truncated and improved GsCelA has almost twice the activity as the un-truncated form, and its thermostability is also further enhanced with T50 reaching 86C and TA50 higher than 100C, making this enzyme extremely useful in industrial processes carried out at high temperatures, such as the pre-treatment of cellulosic animal feeds during the final drying step. This research was supported by grants from Taiwan Ministry of Science and Technology and from Academia Sinica

Enhancement of activity and thermostability of a Geobacillus endoglucanase via a unique self-truncation process

The complete utilization of lignocellulosic biomass requires the hydrolysis of cellulose fibers via the synergistic action of three enzymes: exoglucanase, endoglucanase and beta-glucosidase. GsCelA is a 368-amino-acid endoglucanase secreted from a thermophilic Geobacillus sp. 70PC53 that was isolated form a rice straw compost in south Taiwan. GsCelA belongs to the glycosyl hydrolase family 5 and has a typical TIM barrel structure. This enzyme has excellent lignocellulolytic activity and high thermostability, with optimal temperature at 60℃ and pH at 5.0. The purified GsCelA is capable of carrying out a unique self-truncation process at temperature higher than 10 ℃ with optimal pH at 6-7. This self-truncation process is not due to the action of contaminating proteases and it can be suppressed by EDTA and EGTA, and enhanced by divalent metal ions. This self-truncation process also takes place in vivo in Geobacillus sp. 70PC53. The spontaneous or engineered C-terminal truncation up to 60 amino acids from the C-terminus improves GsCelA specific activity and renders the enzyme more thermostable. To investigate the importance of specific amino acids on the enzymatic activity of GsCelA, site-directed mutagenesis and protein engineering approach were employed to alter amino acid residues unique to this enzyme. It was demonstrated that point mutations Y195T , D55S, G288T and D289L replacements increase the activity of this enzyme by 30%

Long Non Coding RNA MALAT1 Promotes Tumor Growth and Metastasis by Inducing Epithelial-Mesenchymal Transition in Oral Squamous Cell Carcinoma

The prognosis of advanced oral squamous cell carcinoma (OSCC) patients remains dismal, and a better understanding of the underlying mechanisms is critical for identifying effective targets with therapeutic potential to improve the survival of patients with OSCC. This study aims to clarify the clinical and biological significance of metastasis-associated long non-coding RNA, metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) in OSCC. We found that MALAT1 is overexpressed in OSCC tissues compared to normal oral mucosa by real-time PCR. MALAT1 served as a new prognostic factor in OSCC patients. When knockdown by small interfering RNA (siRNA) in OSCC cell lines TSCCA and Tca8113, MALAT1 was shown to be required for maintaining epithelial-mesenchymal transition (EMT) mediated cell migration and invasion. Western blot and immunofluorescence staining showed that MALAT1 knockdown significantly suppressed N-cadherin and Vimentin expression but induced E-cadherin expression in vitro. Meanwhile, both nucleus and cytoplasm levels of β-catenin and NF-κB were attenuated, while elevated MALAT1 level triggered the expression of β-catenin and NF-κB. More importantly, targeting MALAT1 inhibited TSCCA cell-induced xenograft tumor growth in vivo. Therefore, these findings provide mechanistic insight into the role of MALAT1 in regulating OSCC metastasis, suggesting that MALAT1 is an important prognostic factor and therapeutic target for OSCC

ESTIMATION IN A PROPORTIONAL HAZARD MODEL FOR SEMI-MARKOV COUNTING PROCESS

Abstract: Estimation is studied in a regression model for counting processes whose baseline intensity processes are of semi-Markov form. Asymptotic normality is established for a Breslow-type estimator of the cumulative baseline hazard for each gap time of the counting process

Vitamin D Signaling through Induction of Paneth Cell Defensins Maintains Gut Microbiota and Improves Metabolic Disorders and Hepatic Steatosis in Animal Models.

Metabolic syndrome (MetS), characterized as obesity, insulin resistance, and non-alcoholic fatty liver diseases (NAFLD), is associated with vitamin D insufficiency/deficiency in epidemiological studies, while the underlying mechanism is poorly addressed. On the other hand, disorder of gut microbiota, namely dysbiosis, is known to cause MetS and NAFLD. It is also known that systemic inflammation blocks insulin signaling pathways, leading to insulin resistance and glucose intolerance, which are the driving force for hepatic steatosis. Vitamin D receptor (VDR) is highly expressed in the ileum of the small intestine, which prompted us to test a hypothesis that vitamin D signaling may determine the enterotype of gut microbiota through regulating the intestinal interface. Here, we demonstrate that high-fat-diet feeding (HFD) is necessary but not sufficient, while additional vitamin D deficiency (VDD) as a second hit is needed, to induce robust insulin resistance and fatty liver. Under the two hits (HFD+VDD), the Paneth cell-specific alpha-defensins including α-defensin 5 (DEFA5), MMP7 which activates the pro-defensins, as well as tight junction genes, and MUC2 are all suppressed in the ileum, resulting in mucosal collapse, increased gut permeability, dysbiosis, endotoxemia, systemic inflammation which underlie insulin resistance and hepatic steatosis. Moreover, under the vitamin D deficient high fat feeding (HFD+VDD), Helicobacter hepaticus, a known murine hepatic-pathogen, is substantially amplified in the ileum, while Akkermansia muciniphila, a beneficial symbiotic, is diminished. Likewise, the VD receptor (VDR) knockout mice exhibit similar phenotypes, showing down regulation of alpha-defensins and MMP7 in the ileum, increased Helicobacter hepaticus and suppressed Akkermansia muciniphila. Remarkably, oral administration of DEFA5 restored eubiosys, showing suppression of Helicobacter hepaticus and increase of Akkermansia muciniphila in association with resolving metabolic disorders and fatty liver in the HFD+VDD mice. An in vitro analysis showed that DEFA5 peptide could directly suppress Helicobacter hepaticus. Thus, the results of this study reveal critical roles of a vitamin D/VDR axis in optimal expression of defensins and tight junction genes in support of intestinal integrity and eubiosis to suppress NAFLD and metabolic disorders

Areca Users in Combination with Tobacco and Alcohol Use Are Associated with Younger Age of Diagnosed Esophageal Cancer in Taiwanese Men

BACKGROUND: Whether the habitual use of substances (tobacco, alcohol, or areca nut (seed of the Areca palm)) can affect the age of esophageal squamous cell carcinoma (ESCC) presentation has rarely been examined. METHODS: The study subjects were those who were males and the first time to be diagnosed as ESCC (ICD-9 150) and who visited any of three medical centers in Taiwan between 2000 and 2009. A standardized questionnaire was used to collect substance uses and other variables. RESULTS: Mean age (±SD) at presentation of ESCC was 59.2 (±11.3) years in a total of 668 cases. After adjusting for other covariates, alcohol drinkers were 3.58 years younger to have ESCC than non-drinkers (p = 0.002). A similar result was found among areca chewers, who were 6.34 years younger to have ESCC than non-chewers (p<0.0001), but not among cigarette smokers (p = 0.10). When compared to the group using 0-1 substances, subjects using both cigarettes and alcohol were nearly 3 years younger to contract ESCC. Furthermore, those who use areca plus another substance were 7-8 years younger. Subjects using all three substances had the greatest age difference, 9.20 years younger (p<0.0001), compared to the comparison group. CONCLUSION: Our findings suggest that habitually consuming tobacco, alcohol, and areca nut can influence the age-onset of ESCC. Since the development of ESCC is insidious and life-threatening, our observation is worthy to be reconfirmed in the large-scale and long-term follow-up prospective cohort studies to recommend the screening strategy of this disease

Tetra­aqua­bis(2-oxo-1,2-dihydro­quinoline-4-carboxyl­ato-κO 4)nickel(II)

In the title compound, [Ni(C10H6NO3)2(H2O)4], the central NiII atom is located on an inversion center and coordinated in a slightly distorted octa­hedral geometry by two O atoms from two 2-oxo-1,2-dihydro­quinoline-4-carboxyl­ate ligands and four water mol­ecules, all of which act as monodentate ligands. The crystal structure features an extensive network of inter­molecular hydrogen-bonding inter­actions (O—H⋯O and N—H⋯O) and offset face-to-face π–π stacking inter­actions [centroid–centroid distances = 3.525 (3) and 3.281 (5) Å]