Polypeptide binding specificities of Saccharomyces cerevisiae oligosaccharyltransferase accessory proteins Ost3p and Ost6p

Asparagine-linked glycosylation is a common and vital co- and post-translocational modification of diverse secretory and membrane proteins in eukaryotes that is catalyzed by the multiprotein complex oligosaccharyltransferase (OTase). Two isoforms of OTase are present in Saccharomyces cerevisiae, defined by the presence of either of the homologous proteins Ost3p or Ost6p, which possess different protein substrate specificities at the level of individual glycosylation sites. Here we present in vitro characterization of the polypeptide binding activity of these two subunits of the yeast enzyme, and show that the peptide-binding grooves in these proteins can transiently bind stretches of polypeptide with amino acid characteristics complementary to the characteristics of the grooves. We show that Ost6p, which has a peptide-binding groove with a strongly hydrophobic base lined by neutral and basic residues, binds peptides enriched in hydrophobic and acidic amino acids. Further, by introducing basic residues in place of the wild type neutral residues lining the peptide-binding groove of Ost3p, we engineer binding of a hydrophobic and acidic peptide. Our data supports a model of Ost3/6p function in which they transiently bind stretches of nascent polypeptide substrate to inhibit protein folding, thereby increasing glycosylation efficiency at nearby asparagine residues.     

Variation the oviposition behavior by the stingless bee,Heterotrigona itama (Hymenoptera,Apidae, Meliponini)

A study to determine the variation of ovipositioning behavior of stingless bees, Heterotrigona itama (Cockerell, 1918) was conducted on three colonies on June 2015. A digital single-lens reflex (DSLR) camera with a macro lens attached was used to record every movement of H. itama in its colonies for 20 min hour between 0800 h and 2000 h for seven days and seven month. The daily egg laying rate and time for laying eggs in colony-B and colony-C were significantly (P ? 0.05) higher than the colony-A. However, time to close the brood was not significantly different among colonies. The fastest egg oviposition time was 4 s by the colony-B and the slowest was 6 s by the colony-A. In addition there are no significant trends on brood produced per day, laying time of eggs, and the closing time of the brood after the oviposition process from June to December 2016. This result is useful for understanding the behavior of egg laying process by the queen bees and necessary to deal with problems of management and reproduction in the near future.     

Biotechnological route for sustainable succinate production utilizing oil palm frond and kenaf as potential carbon sources

Applied Microbiology and Biotechnology - Due to the world’s dwindling energy supplies, greater thrust has been placed on the utilization of renewable resources for global succinate...     

Proteomic Profile of Human Schwann Cells

Schwann cells (SC) are essential for the growth, maintenance, and regeneration of peripheral nerves, but the proteome of normal human SC is poorly defined. Here, a proteomic analysis by LC–MS/MS is performed to define the protein expression profile of primary human SC. A total of 19 557 unique peptides corresponding to 1553 individual proteins are identified. Ingenuity Pathway Analysis (IPA), Gene Ontology (GO), and Database for Annotation, Visualization, and Integrated Discovery (DAVID) are used to assign protein localization and function, and to define enriched pathways. EIF2, mTOR, and integrin signaling are among the most enriched pathways and the most enriched biological function is cell–cell adhesion, which is in agreement with the supportive role of SC in peripheral nerves. In addition, several nociceptors and synaptic proteins are identified and may contribute to the recently discovered role of SC in pain sensation and cancer progression. This proteome analysis of normal human SC constitutes a reference for future molecular explorations of physiological and pathological processes where SC are involved.     

A pilot study on the association between SLCO1B1 RS4363657 polymorphism and muscle adverse events in adults with newly diagnosed dyslipidaemia who were prescribed a statin: the Malaysian primary health care cohort

Abstract

Introduction: Statin, the first-line treatment for dyslipidaemia, may have suboptimal adherence due to its associated muscle adverse events. These data, however, remain limited.

Aim: To determine the association of serum creatine kinase (CK) and SLCO1B1 rs4363657 polymorphism with statin-associated muscle adverse events (SAMAE) among dyslipidaemia participants.

Methods: This was a prospective cohort study at government health clinics involving newly diagnosed adults with dyslipidaemia. SAMAE were recorded based on the patient’s complaint after a month on statin. CK was taken at baseline and follow-up. Genetic profiling was performed for SLCO1B1 rs4363657 polymorphism.

Results: Among 118 participants, majority were Malay (72%) males (61%) with a mean age of 49?±?12.2 years old and prescribed lovastatin (61.9). There was a significant association between statin types (lovastatin and simvastatin) and SAMAE (p?=?0.0327); no significant association noted between CK and SAMAE (p?=?0.5637). The SLCO1B1 rs4363657 polymorphism was significantly associated SAMAE (p?<?0.0001).

Conclusions: In this first pilot study of a multiethnic Malaysian population, the incidence of SAMAE was 18.6%. SAMAE were significantly higher in subjects on lovastatin compared to simvastatin. SLCO1B1 rs4363657 polymorphism was a significant risk factor for SAMAE.     

Molecular detection of Epstein–Barr virus in different types of lymphoma

Molecular Biology Reports - Epstein-Barr virus (EBV) is a member of the γ herpesvirus subfamily. It is widely spread, potentially oncogenic and has been studied in different human cancers such...     

A Fatal Case of <Emphasis Type="Italic">Candida auris</Emphasis> and <Emphasis Type="Italic">Candida tropicalis</Emphasis> Candidemia in Neutropenic Patient

We report a fatal case of Candida auris that was involved in mixed candidemia with Candida tropicalis, isolated from the blood of a neutropenic patient. Identification of both isolates was confirmed by amplification and sequencing of internal transcribed spacer and D1/D2 domain of large subunit in rRNA gene. Antifungal susceptibility test by E-test method revealed that C. auris was resistant to amphotericin B, anidulafungin, caspofungin, fluconazole, itraconazole and voriconazole. On the other hand, C. tropicalis was sensitive to all antifungal tested. The use of chromogenic agar as isolation media is vital in detecting mixed candidemia.     

Proteomic Analysis of Stromal and Epithelial Cell Communications in Human Endometrial Cancer Using a Unique 3D Co‐Culture Model

Epithelial and stromal communications are essential for normal uterine functions and their dysregulation contributes to the pathogenesis of many diseases including infertility, endometriosis, and cancer. Although many studies have highlighted the advantages of culturing cells in 3D compared to the conventional 2D culture system, one of the major limitations of these systems is the lack of incorporation of cells from non‐epithelial lineages. In an effort to develop a culture system incorporating both stromal and epithelial cells, 3D endometrial cancer spheroids are developed by co‐culturing endometrial stromal cells with cancerous epithelial cells. The spheroids developed by this method are phenotypically comparable to in vivo endometrial cancer tissue. Proteomic analysis of the co‐culture spheroids comparable to human endometrial tissue revealed 591 common proteins and canonical pathways that are closely related to endometrium biology. To determine the feasibility of using this model for drug screening, the efficacy of tamoxifen and everolimus is tested. In summary, a unique 3D model system of human endometrial cancer is developed that will serve as the foundation for the further development of 3D culture systems incorporating different cell types of the human uterus for deciphering the contributions of non‐epithelial cells present in cancer microenvironment.     

Structural insights into the mechanism of the PLP synthase holoenzyme from Thermotoga maritima

Pyridoxal 5'-phosphate (PLP) is the biologically active form of vitamin B6 and is an important cofactor for several of the enzymes involved in the metabolism of amine-containing natural products such as amino acids and amino sugars. The PLP synthase holoenzyme consists of two subunits: YaaD catalyzes the condensation of ribulose 5-phosphate, glyceraldehyde-3-phosphate, and ammonia, and YaaE catalyzes the production of ammonia from glutamine. Here we describe the structure of the PLP synthase complex (YaaD-YaaE) from Thermotoga maritima at 2.9 A resolution. This complex consists of a core of 12 YaaD monomers with 12 noninteracting YaaE monomers attached to the core. Compared with the previously published structure of PdxS (a YaaD ortholog in Geobacillus stearothermophilus), the N-terminus (1-18), which includes helix alpha0, the beta2-alpha2 loop (46-56), which includes new helix alpha2a, and the C-terminus (270-280) of YaaD are ordered in the complex but disordered in PdxS. A ribulose 5-phosphate is bound to YaaD via an imine with Lys82. Previous studies have demonstrated a similar imine at Lys149 and not at Lys81 (equivalent to Lys150 and Lys82 in T. maritima) for the Bacillus subtilis enzyme suggesting the possibility that two separate sites on YaaD are involved in PLP formation. A phosphate from the crystallization solution is found bound to YaaD and also serves as a marker for a possible second active site. An ammonia channel that connects the active site of YaaE with the ribulose 5-phosphate binding site was identified. This channel is similar to one found in imidazole glycerol phosphate synthase; however, when the beta-barrels of the two complexes are superimposed, the glutaminase domains are rotated by about 180 degrees with respect to each other.