Aquisphaera insulae sp. nov., a new member in the family Isosphaeraceae,isolated from the floating island of Loktak lake and emended description of the genus Aquisphaera

Antonie van Leeuwenhoek - Strain JC669T was isolated from a floating island of Loktak lake, Manipur, India and shares the highest 16S rRNA gene sequence identity with Aquisphaera giovannonii OJF2T....     

A genomic overview including polyphasic taxonomy of Thalassoroseus pseudoceratinae gen. nov., sp. nov. isolated from a marine sponge,Pseudoceratina sp.

A pink-coloured, salt- and alkali-tolerant planctomycetal strain (JC658^T) with oval to pear-shaped, motile, aerobic, Gram-negative stained cells was isolated from a marine sponge, Pseudoceratina sp. Strain JC658^T shares the highest 16S rRNA gene sequence identity with Maioricimonas rarisocia Mal4^T (<?89.2%) in the family Planctomycetaceae. The genomic analysis of the new strain indicates its biotechnological potential for the production of various industrially important enzymes, notably sulfatases and carbohydrate-active enzymes (CAZymes), and also potential antimicrobial compounds. Several genes encoding restriction-modification (RM) and CRISPR-CAS systems are also present. NaCl is obligate for growth, of which strain JC658^T can tolerate a concentration up to 6% (w/v). Optimum pH and temperature for growth are 8.0 (range 7.0–9.0) and 25 ºC (range 10–40 °C), respectively. The major respiratory quinone of strain JC658^T is MK6. Major fatty acids are C_16:1ω7c/C_16:1ω6c, C_18:0 and C_16:0. Major polar lipids are phosphatidylcholine, phosphatidyl-dimethylethanolamine and phosphatidyl-monomethylethanolamine. The genomic size of strain JC658^T is 7.36 Mb with a DNA G?+?C?content of 54.6 mol%. Based on phylogenetic, genomic (ANI, AAI, POCP, dDDH), chemotaxonomic, physiological and biochemical characteristics, we conclude that strain JC658^T belongs to a novel genus and constitutes a novel species within the family Planctomycetaceae, for which we propose the name Thalassoroseus pseudoceratinae gen. nov., sp. nov. The novel species is represented by the type strain JC658^T (=?KCTC 72881 ^T?=?NBRC 114371 ^T).

     

Comparison of pyruvate decarboxylases from Saccharomyces cerevisiae and Komagataella pastoris (Pichia pastoris)

Pyruvate decarboxylases (PDCs) are a class of enzymes which carry out the non-oxidative decarboxylation of pyruvate to acetaldehyde. These enzymes are also capable of carboligation reactions and can generate chiral intermediates of substantial pharmaceutical interest. Typically, the decarboxylation and carboligation processes are carried out using whole cell systems. However, fermentative organisms such as Saccharomyces cerevisiae are known to contain several PDC isozymes; the precise suitability and role of each of these isozymes in these processes is not well understood. S. cerevisiae has three catalytic isozymes of pyruvate decarboxylase (ScPDCs). Of these, ScPDC1 has been investigated in detail by various groups with the other two catalytic isozymes, ScPDC5 and ScPDC6 being less well characterized. Pyruvate decarboxylase activity can also be detected in the cell lysates of Komagataella pastoris, a Crabtree-negative yeast, and consequently it is of interest to investigate whether this enzyme has different kinetic properties. This is also the first report of the expression and functional characterization of pyruvate decarboxylase from K. pastoris (PpPDC). This investigation helps in understanding the roles of the three isozymes at different phases of S. cerevisiae fermentation as well as their relevance for ethanol and carboligation reactions. The kinetic and physical properties of the four isozymes were determined using similar conditions of expression and characterization. ScPDC5 has comparable decarboxylation efficiency to that of ScPDC1; however, the former has the highest rate of reaction, and thus can be used for industrial production of ethanol. ScPDC6 has the least decarboxylation efficiency of all three isozymes of S. cerevisiae. PpPDC in comparison to all isozymes of S. cerevisiae is less efficient at decarboxylation. All the enzymes exhibit allostery, indicating that they are substrate activated.     

Alternative Signaling Pathways as Potential Therapeutic Targets for Overcoming EGFR and c-Met Inhibitor Resistance in Non-Small Cell Lung Cancer

The use of tyrosine kinase inhibitors (TKIs) against EGFR/c-Met in non-small cell lung cancer (NSCLC) has been shown to be effective in increasing patient progression free survival (PFS), but their efficacy is limited due to the development of resistance and tumor recurrence. Therefore, understanding the molecular mechanisms underlying development of drug resistance in NSCLC is necessary for developing novel and effective therapeutic approaches to improve patient outcome. This study aims to understand the mechanism of EGFR/c-Met tyrosine kinase inhibitor (TKI) resistance in NSCLC. H2170 and H358 cell lines were made resistant to SU11274, a c-Met inhibitor, and erlotinib, an EGFR inhibitor, through step-wise increases in TKI exposure. The IC₅₀ concentrations of resistant lines exhibited a 4–5 and 11–22-fold increase for SU11274 and erlotinib, respectively, when compared to parental lines. Furthermore, mTOR and Wnt signaling was studied in both cell lines to determine their roles in mediating TKI resistance. We observed a 2–4-fold upregulation of mTOR signaling proteins and a 2- to 8-fold upregulation of Wnt signaling proteins in H2170 erlotinib and SU11274 resistant cells. H2170 and H358 cells were further treated with the mTOR inhibitor everolimus and the Wnt inhibitor XAV939. H358 resistant cells were inhibited by 95% by a triple combination of everolimus, erlotinib and SU11274 in comparison to 34% by a double combination of these drugs. Parental H2170 cells displayed no sensitivity to XAV939, while resistant cells were significantly inhibited (39%) by XAV939 as a single agent, as well as in combination with SU11274 and erlotinib. Similar results were obtained with H358 resistant cells. This study suggests a novel molecular mechanism of drug resistance in lung cancer.