1.Discovery and characterization of bicereucin, an unusual D-amino acid-containing mixed two-component lantibiotic.
Huo L, van der Donk WA. J Am Chem Soc. 2016 Apr 13. [Epub ahead of print]
Lantibiotics are a group of ribosomally synthesized and post-translationally modified peptides (RiPPs) exhibiting antimicrobial activity. They are characterized by the presence of the thioether-containing bisamino acids lanthionine and methyllanthionine. In this study, we report a two-component lantibiotic from Bacillus cereus SJ1 with unusual structural features that we named bicereucin. Unlike all previous two-component lantibiotics, only one of the two peptides of bicereucin contains a lanthionine. The second peptide lacks any cysteines but contains several D-amino acids. These are installed by the dehydrogenase BsjJB, the activity of which was successfully reconstituted in vitro. The proteolytic re-moval of the leader peptide was also performed in vitro. Bicereucin displayed synergistic anti-microbial activities against gram-positive strains including methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococci (VRE) as well as hemolytic activity.
2.Autophagy protects ovarian cancer-associated fibroblasts against oxidative stress.
Wang Q1,2, Xue L3, Zhang X3, Bu S1, Zhu X3, Lai D1. Cell Cycle. 2016 Apr 13:0. [Epub ahead of print]
RNA-Seq and gene set enrichment anylysis revealed that ovarian cancer associated fibroblasts (CAFs) are mitotically active compared with normal fibroblasts (NFs). Cellular senescence is observed in CAFs treated with H2O2 as shown by elevated SA-β-gal activity and p21 (WAF1/Cip1) protein levels. Reactive oxygen species (ROS) production and p21 (WAF1/Cip1) elevation may account for H2O2-induced CAFs cell cycle arrest in S phase. Blockage of autophagy can increase ROS production in CAFs, leading to cell cycle arrest in S phase, cell proliferation inhibition and enhanced sensitivity to H2O2-induced cell death. ROS scavenger NAC can reduce ROS production and thus restore cell viability. Lactate dehydrogenase A (LDHA), monocarboxylic acid transporter 4 (MCT4) and superoxide dismutase 2 (SOD2) were up-regulated in CAFs compared with NFs. There was relatively high lactate content in CAFs than in NFs. Blockage of autophagy decreased LDHA, MCT4 and SOD2 protein levels in CAFs that might enhance ROS production.
3.Development and characterization of a potent free fatty acid receptor 1 (FFA1) fluorescent tracer.
Christiansen E, Hudson BD, Hansen AH, Milligan G, Ulven T. J Med Chem. 2016 Apr 13. [Epub ahead of print]
The free fatty acid receptor 1 (FFA1/GPR40) is a potential target for treatment of type 2 diabetes. Although several potent agonists have been described, there remains a strong need for suitable tracers to interrogate ligand binding to this receptor. We address this by exploring fluorophore-tethering to known potent FFA1 agonists. This led to the development of 4, a high affinity FFA1 tracer with favorable and polarity-dependent fluorescent properties. A close to ideal overlap between the emission spectrum of the NanoLuciferase receptor tag and the excitation spectrum of 4 enabled the establishment of a homogenous BRET-based binding assay suitable for both detailed kinetic studies and high throughput competition binding studies. Using 4 as a tracer demonstrated that the compound acts fully competitively with selected synthetic agonists but not with lauric acid and allowed for the characterization of binding affinities of a diverse selection of known FFA1 agonists, indicating that 4 will be a valuable tool for future studies at FFA1.
4.Characterization of Glycolytic Pathway Genes Using RNA-Seq in Developing Kernels of Eucommia ulmoides.
Feng Y, Zhang L, Fu J, Li F, Wang L, Tan X, Mo W, Cao H. J Agric Food Chem. 2016 Apr 13. [Epub ahead of print]
Eucommia ulmoides Oliver, the only member of the Eucommiaceae family, is a rare and valuable tree used to produce a highly valued traditional Chinese medicine and contains α-linolenic acid (ALA) up to 60% of the total fatty acids in the kernels (embryos). Glycolysis provides both cellular energy and the intermediates for other biosynthetic processes. However, nothing was known about the molecular basis of the glycolytic pathway in E. ulmoides kernels. The purposes of this study were to identify novel genes of E. ulmoides related to glycolytic metabolism and to analyze the expression patterns of selected genes in the kernels. Transcriptome sequencing based on the Illumina platform generated 96,469 unigenes in four cDNA libraries constructed using RNAs from 70 and 160 days after flowering kernels of both low and high ALA varieties. We identified and characterized the digital expression of 120 unigenes coding for 24 protein families involved in kernel glycolytic pathway.
