Effect and mechanism of oritavancin on hIAPP amyloid formation.

Amyloidosis of the human islet amyloid polypeptide (hIAPP) is closely related to the pathogenesis of type 2 diabetes (T2D) and serves as both a diagnostic hallmark and a key therapeutic target for T2D. In this study, we discovered that oritavancin (Ori), a glycopeptide antibiotic primarily prescribed for Gram-positive bacterial infections, can dose-dependently inhibit recombinant hIAPP (rhIAPP) amyloid formation. Ori specifically inhibited rhIAPP amyloid formation at the initial nucleation stage but didn't affect mature rhIAPP fibrils.

Endotoxin accelerates insulin amyloid formation and inactivates insulin signal transduction.

Aims And Objectives: The aim of this study is to discuss the influence of endotoxin on insulin amyloid formation, to provide guidance for therapeutic insulin preparation and storage.

Materials And Methods: The ThT and ANS binding assays were applied to characterize the dynamics curve of insulin amyloid formation with the presence or absence of endotoxin. The morphological structures of intermediate and mature insulin fibrils were observed with SEM and TEM.

Characterizing of a new α-agarase AgaE from Thalassomonas sp. LD5 and probing its catalytically essential residues.

A new α-agarase AgaE belonging to glycoside hydrolase (GH) family 96 was identified and cloned from marine bacterium Thalassomonas sp. LD5. AgaE consists of 926 amino acids with a theoretical molecular mass of 97 kDa.

Identification of Crocin as a New hIAPP Amyloid Inhibitor via a Simple Yet Highly Biospecific Screening System.

Amylin (hIAPP) amyloid formation plays an important role in the pathogenesis of type 2 diabetes (T2D), which makes it a promising therapeutic target for T2D. In this study, we established a screening tool for identifying chemicals affecting hIAPP amyloid formation based on a reported genetic tool, which constantly tracks protein aggregates in Saccharomyces cerevisiae. In order to obtain the hIAPP with better aggregation ability, the gene of hIAPP was tandemly ligated to create 1×, 2×, 4× or 6×-hIAPP expressing strains.

Characterization of the hydrolysate and catalytic cavity of α-agarase AgaD.

Objective: To characterize the hydrolysis product and the substrate binding in the catalytic cavity of α-agarase AgaD.

Results: The time course curve showed that AgaD degraded agarose by the endo-type cleavage. AgaD did not degrade agarobiose (A2) and agarotetraose (A4).

Chitosan Oligosaccharides Attenuate Amyloid Formation of hIAPP and Protect Pancreatic β-Cells from Cytotoxicity.

The deposition of aggregated human islet amyloid polypeptide (hIAPP) in the pancreas, that has been associated with β-cell dysfunction, is one of the common pathological features of patients with type 2 diabetes (T2D). Therefore, hIAPP aggregation inhibitors hold a promising therapeutic schedule for T2D. Chitosan oligosaccharides (COS) have been reported to exhibit a potential antidiabetic effect, but the function of COS on hIAPP amyloid formation remains elusive.

Characterization of an α-agarase from Thalassomonas sp. LD5 and its hydrolysate.

It has been a long time since the first α-agarase was discovered. However, only two α-agarases have been cloned and partially characterized so far and the study of α-agarases has lagged far behind that of β-agarases. Here, we report an α-agarase, AgaD, cloned from marine bacterium Thalassomonas sp.

Erratum to: N-Terminal seven-amino-acid extension simultaneously improves the pH stability, optimal temperature, thermostability and catalytic efficiency of chitosanase CsnA.

In Table 1 as published, some of the data were wrong. The corrected Table 1 is shown below.

Erratum to: Thermostability enhancement of chitosanase CsnA by fusion a family 5 carbohydrate-binding module.

In Table 1 as published, some of the data were wrong. The corrected Table 1 is shown here. In addition, according to the corrected Table 1, the sentence "the k /K of CsnA-CBM5 was higher than that of WT by 143%" in the part of "The kinetic parameters and specific activity" in the Results part should be changed to "the k /K of CsnA-CBM5 was higher than that of WT by 110%".

The hydrogen-bond network around Glu160 contributes to the structural stability of chitosanase CsnA from Renibacterium sp. QD1.

CsnA, a chitosanase from Renibacterium sp. QD1, has great potential for industrial applications due to its high yield and broad pH stability. In this study, a specific Glu160 in CsnA was identified by sequence alignment, and structural analysis and MD simulation predicted that Glu160 formed a hydrogen-bond network with Lys163 and Thr114.

O-GlcNAcylation of SIRT1 enhances its deacetylase activity and promotes cytoprotection under stress.

SIRT1 is the most evolutionarily conserved mammalian sirtuin, and it plays a vital role in the regulation of metabolism, stress responses, genome stability, and ageing. As a stress sensor, SIRT1 deacetylase activity is significantly increased during stresses, but the molecular mechanisms are not yet fully clear. Here, we show that SIRT1 is dynamically modified with O-GlcNAc at Ser 549 in its carboxy-terminal region, which directly increases its deacetylase activity both in vitro and in vivo.

N-Terminal seven-amino-acid extension simultaneously improves the pH stability, optimal temperature, thermostability and catalytic efficiency of chitosanase CsnA.

Objective: To determine the effects of the extra N-terminal seven-amino-acid sequence on the function of chitosanase CsnA.

Results: Sequence and structure analysis indicated that the mature CsnA contains a seven-amino-acid extension in a disordered form at the N-terminus. To determine the function of this sequence, both mature CsnA and its N-terminus-truncated mutant, CsnAΔN, were expressed in Escherichia coli and characterized.

Thermostability enhancement of chitosanase CsnA by fusion a family 5 carbohydrate-binding module.

Objective: To determine the effects of carbohydrate-binding modules (CBMs) on the thermostability and catalytic efficiency of chitosanase CsnA.

Results: Three CBMs (BgCBM5, PfCBM32-2 and AoCBM35) were engineered at the C-terminus of chitosanase CsnA to create hybrid enzymes CsnA-CBM5, CsnA-CBM32 and CsnA-CBM35. K values of all the hybrid enzymes were lower than that of the wild type (WT) enzyme; however, only CsnA-CBM5 had an elevated specific activity and catalytic efficiency.

[High expression of agarase AgaD in Escherichia coli].

Objective: We constructed highly efficient expression systems for agarase AgaD and optimized its culture conditions.

Methods: First, the codon usage of AgaD was optimized to make it suitable for expression in E. coli.

Antibiotics at subinhibitory concentrations improve the quorum sensing behavior of Chromobacterium violaceum.

Increasing evidence has shown that antibiotics function as intermicrobial signaling molecules instead of killing weapons. However, mechanisms and key factors that are involved in such functions remain poorly understood. Earlier findings have associated antibiotic signaling with quorum sensing (QS); however, results varied among experiments, antibiotics, and bacterial strains.

[Molecular cloning and preliminary functional study of TRBP].

Aim: Construct prokaryotic expression vector carrying mouse TRBP (TAR RNA-binding protein) gene and test the double-stranded RNA binding ability of TRBP.

Methods: RT-PCR was used to obtain TRBP cDNA from mouse genomic DNA. Then, we built the His-tag fusion expression vector of TRBP and transformed it into E.

[Construction of Staphylococcus aureus RN6390 hmp gene mutant and analysis of NO sensitivity].

Object: To investigate the function of flavohaemoglobin (HMP) in Staphylococcus aureus RN6390 under the nitrification pressure, we constructed the hmp gene deletion mutant of RN6390 strain.

Methods: According to principle of homologous recombination, we obtained the up stream and down stream sequences of hmp gene by PCR using chromosomal DNA of S. aureus RN6390 as template.

Antibiofilm activity of an exopolysaccharide from marine bacterium Vibrio sp. QY101.

Bacterial exopolysaccharides have always been suggested to play crucial roles in the bacterial initial adhesion and the development of complex architecture in the later stages of bacterial biofilm formation. However, Escherichia coli group II capsular polysaccharide was characterized to exert broad-spectrum biofilm inhibition activity. In this study, we firstly reported that a bacterial exopolysaccharide (A101) not only inhibits biofilm formation of many bacteria but also disrupts established biofilm of some strains.

Artificial trans-encoded small non-coding RNAs specifically silence the selected gene expression in bacteria.

Recently, many small non-coding RNAs (sRNAs) with important regulatory roles have been identified in bacteria. As their eukaryotic counterparts, a major class of bacterial trans-encoded sRNAs acts by basepairing with target mRNAs, resulting in changes in translation and stability of the mRNA. RNA interference (RNAi) has become a powerful gene silencing tool in eukaryotes.

GlcNAcylation plays an essential role in breast cancer metastasis.

GlcNAcylation, a dynamic posttranslational modification, is involved in a wide range of biological processes and some human diseases. Although there is emerging evidence that some tumor-associated proteins are modified by GlcNAcylation, the role of GlcNAcylation in tumor progression remains unclear. Here, we show that GlcNAcylation enhances the migration/invasion of breast cancer cells in vitro and lung metastasis in vivo.

Cloning, expression and characterization of a new agarase-encoding gene from marine Pseudoalteromonas sp.

The beta-agarase gene agaA, cloned from a marine bacterium, Pseudoalteromonas sp. CY24, consists of 1,359 nucleotides encoding 453 amino acids in a sequence corresponding to a catalytic domain of glycosyl hydrolase family 16 (GH16) and a carbohydrate-binding module type 13 (CBM13). The recombinant enzyme is an endo-type agarase that hydrolyzes beta-1,4-linkages of agarose, yielding neoagarotetraose and neoagarohexaose as the predominant products.

Enhancing the thermostability of a novel beta-agarase AgaB through directed evolution.

To increase the thermostability of beta-agarase AgaB by directed evolution, the mutant gene libraries were generated by error-prone polymerase chain reaction (PCR) and deoxyribonucleic acid (DNA) shuffling. Mutants with high thermostability were screened by a simple method based on agarase-degrading agar to generate a clear zone on the agar plate. A mutant S2 was obtained through two rounds of error-prone PCR and a single round of DNA shuffling and selection.

[Correlation of heat shock protein 70 expression in nasopharyngeal carcinoma to immunoglobin A against viral capsid antigen of Epstein-Barr virus in sera and its clinical significance].

Background & Objective: Overexpression of heat shock protein (HSP)70 is expressed in many tumors, but the correlation of its overexpression in nasopharyngeal carcinoma (NPC) to immunoglobin A against viral capsid antigen of Epstein-Barr virus (EBV) in sera and its clinical significance are still unclear. This study was to determine the expression of HSP70 in NPC, and to analyze its correlations to EBV IgA/VCA titer and prognosis.

Methods: The expression of HSP70 in 38 specimens of stage II-III NPC was determined by SP immunohistochemistry; the content of HSP70 in the 38 specimens was detected by ELISA; the EBV IgA/VCA titer in sera of the 38 patients was detected by immunoenzymatic (IE) method.