Production of 2,3-Butanediol from Sucrose by a <Emphasis Type="Italic">Klebsiella</Emphasis> Species

Chemical 2,3-butanediol is an important platform compound possessing diverse industrial applications. So far, it is mainly produced by using petrochemical feedstock which is associated with high cost and adverse environmental impacts. Hence, finding alternative routes (e.g., via fermentation using renewable carbon sources) to produce 2,3-butanediol are urgently needed. In this study, we report a wild-type Klebsiella sp. strain XRM21, which is capable of producing 2,3-butanediol from a wide variety of carbon sources including glucose, sucrose, xylose, and glycerol. Among them, fermentation of sucrose leads to the highest production of 2,3-butanediol. To maximize the production of 2,3-butanediol, fermentation conditions were first optimized for strain XMR21 by using response surface methodology (RSM) in batch reactors. Subsequently, a fed-batch fermentation strategy was designed based on the optimized parameters, where 91.2 g/L of 2,3-butanediol could be produced from substrate sucrose dosing in 100 g/L for three times. Moreover, random mutagenesis of stain XMR21 resulted in a highly productive mutant strain, capable of producing 119.4 and 22.5 g/L of 2,3-butanediol and ethanol under optimized fed-batch fermentation process within 65 h with a total productivity of 2.18 g/L/h, which is comparable to the reported highest 2,3-butanediol concentration produced by previous strains. This study provides a potential strategy to produce industrially important 2,3-butanediol from low-cost sucrose.     

Studies on the interaction of the food colorant tartrazine with double stranded deoxyribonucleic acid

Interaction of the food additive tartrazine with double-stranded DNA was studied by spectroscopic and calorimetric techniques. Absorbance studies revealed that tartrazine exhibited hypochromism in the presence of DNA without any bathochromic effects. Minor groove displacement assay of DAPI and Hoechst 33258 suggested that tartrazine binds in the minor groove of DNA. The complexation was predominantly entropy driven with a smaller but favorable enthalpic contribution to the standard molar Gibbs energy. The equilibrium constant was evaluated to be (3.68?±?.08)?×?10⁴?M^?1 at 298.15?K. The negative standard molar heat capacity value along with an enthalpy–entropy compensation phenomenon proposed the involvement of dominant hydrophobic forces in the binding process. Tartrazine enhanced the thermal stability of DNA by 7.53?K under saturation conditions.     

Identification,design and synthesis of novel pyrazolopyridine influenza virus nonstructural protein 1 antagonists

Nonstructural protein 1 (NS1) plays a crucial function in the replication, spread, and pathogenesis of influenza virus by inhibiting the host innate immune response. Here we report the discovery and optimization of novel pyrazolopyridine NS1 antagonists that can potently inhibit influenza A/PR/8/34 replication in MDCK cells, rescue MDCK cells from cytopathic effects of seasonal influenza A strains, reverse NS1-dependent inhibition of IFN-β gene expression, and suppress the slow growth phenotype in NS1-expressing yeast. These pyrazolopyridines will enable researchers to investigate NS1 function during infection and how antagonists can be utilized in the next generation of treatments for influenza infection.     

Possible role of differentially expressing novel protein markers (ligatin and fibulin‐7) in human aqueous humor and trabecular meshwork tissue in glaucoma progression

The pathological mechanism underlying glaucoma has always been a complex aspect of this permanently blinding disease but proteomic studies have been helpful in elucidating it to a great extent in several studies. This study was designed to evaluate the expression and to get an idea about the function of two novel markers (ligatin and fibulin‐7) identified in human aqueous humor (hAH) in relation to glaucomatous progression. A significant increase in the protein content of glaucomatous hAH compared to that of non‐glaucomatous controls (NG‐Ctrls) was observed. Ligatin, fibulin‐7, and its proteolysis were revealed in hAH of primary open angle glaucoma (POAG), primary angle closure glaucoma (PACG) and NG‐Ctrls. Quantification confirmed no significant difference in expression of ligatin, whereas fibulin‐7 was significantly (P < 0.05) low in hAH of PACG in comparison to NG‐Ctrls and POAG. Importantly the immunohistochemical assay for both indicated their possible involvement in the maintenance of the appropriate structure of TM in vivo. Since oxidative stress is a major contributor to glaucomatous pathogenesis, in vitro analysis of nuclear and cytoplasmic fractions indicated intracellular changes in localization and expression of ligatin upon oxidative insult of human trabecular meshwork (TM) cells. While no such changes were found for fibulin‐7 expression. This was also corroborated with the immunocytochemical assay. Though a study with a small sample size, this is the first report which confirms the presence of ligatin and fibulin‐7 in hAH, quantified their differential expression, and indicated the possibility of their involvement in the maintenance of the TM structure.     

Multivalent Role of Human TFIID in Recruiting Elongation Components at the Promoter-Proximal Region for Transcriptional Control

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Heregulin-induced epigenetic regulation of the utrophin-A promoter

Utrophin is the autosomal homolog of dystrophin, the product of the Duchenne's muscular dystrophy (DMD) locus. Utrophin is of therapeutic interest since its over-expression can compensate dystrophin's absence. Utrophin is enriched at neuromuscular junctions due to heregulin-mediated utrophin-A promoter activation. We demonstrate that heregulin activated MSK1/2 and phosphorylated histone H3 at serine 10 in cultured C2C12 muscle cells, in an ERK-dependent manner. MSK1/2 inhibition suppressed heregulin-mediated utrophin-A activation. MSK1 over-expression potentiated heregulin-mediated utrophin-A activation and chromatin remodeling at the utrophin-A promoter. These results identify MSK1/2 as key effectors modulating utrophin-A expression as well as identify novel targets for DMD therapy.     

Enhanced stability of cis Pro-Pro peptide bond in Pro-Pro-Phe sequence motif

Identification of sequence motifs that favor cis peptide bonds in proteins is important for understanding and designing proteins containing turns mediated by cis peptide conformations. From (1)H NMR solution studies on short peptides, we show that the Pro-Pro peptide bond in Pro-Pro-Phe almost equally populates the cis and trans isomers, with the cis isomer stabilized by a CHc...pi interaction involving the terminal Pro and Phe. We also show that Phe is over-represented at sequence positions immediately following cis Pro-Pro motifs in known protein structures. Our results demonstrate that the Pro-Pro cis conformer in Pro-Pro-Phe sequence motifs is as important as the trans conformer, both in short peptides as well as in natively folded proteins.