Comparison of the structure and activity of glycosylated and asglycosylated human carboxylesterase 1

Human Carboxylesterase 1 (hCES1) is the key liver microsomal enzyme responsible for detoxification and metabolism of a variety of clinical drugs. To analyse the role of the single N-linked glycan on the structure and activity of the enzyme, authentically glycosylated and aglycosylated hCES1, generated by mutating asparagine 79 to glutamine, were produced in human embryonic kidney cells. Purified enzymes were shown to be predominantly trimeric in solution by analytical ultracentrifugation. The purified aglycosylated enzyme was found to be more active than glycosylated hCES1 and analysis of enzyme kinetics revealed that both enzymes exhibit positive cooperativity. Crystal structures of hCES1 a catalytically inactive mutant (S221A) and the aglycosylated enzyme were determined in the absence of any ligand or substrate to high resolutions (1.86 Å, 1.48 Å and 2.01 Å, respectively). Superposition of all three structures showed only minor conformational differences with a root mean square deviations of around 0.5 Å over all Cα positions. Comparison of the active sites of these un-liganded enzymes with the structures of hCES1-ligand complexes showed that side-chains of the catalytic triad were pre-disposed for substrate binding. Overall the results indicate that preventing N-glycosylation of hCES1 does not significantly affect the structure or activity of the enzyme

The structure-function relationship of oncogenic LMTK3

Elucidating signaling driven by lemur tyrosine kinase 3 (LMTK3) could help drug development. Here, we solve the crystal structure of LMTK3 kinase domain to 2.1Å resolution, determine its consensus motif and phosphoproteome, unveiling in vitro and in vivo LMTK3 substrates. Via high-throughput homogeneous time-resolved fluorescence screen coupled with biochemical, cellular, and biophysical assays, we identify a potent LMTK3 small-molecule inhibitor (C28). Functional and mechanistic studies reveal LMTK3 is a heat shock protein 90 (HSP90) client protein, requiring HSP90 for folding and stability, while C28 promotes proteasome-mediated degradation of LMTK3. Pharmacologic inhibition of LMTK3 decreases proliferation of cancer cell lines in the NCI-60 panel, with a concomitant increase in apoptosis in breast cancer cells, recapitulating effects of LMTK3 gene silencing. Furthermore, LMTK3 inhibition reduces growth of xenograft and transgenic breast cancer mouse models without displaying systemic toxicity at effective doses. Our data reinforce LMTK3 as a druggable target for cancer therap

The Vitamin B1 Metabolism of Staphylococcus aureus Is Controlled at Enzymatic and Transcriptional Levels

Vitamin B1 is in its active form thiamine pyrophosphate (TPP), an essential cofactor for several key enzymes in the carbohydrate metabolism. Mammals must salvage this crucial nutrient from their diet in order to complement the deficiency of de novo synthesis. In the human pathogenic bacterium Staphylococcus aureus, two operons were identified which are involved in vitamin B1 metabolism. The first operon encodes for the thiaminase type II (TenA), 4-amino-5-hydroxymethyl-2-methylpyrimidine kinase (ThiD), 5-(2-hydroxyethyl)-4-methylthiazole kinase (ThiM) and thiamine phosphate synthase (ThiE). The second operon encodes a phosphatase, an epimerase and the thiamine pyrophosphokinase (TPK). The open reading frames of the individual operons were cloned, their corresponding proteins were recombinantly expressed and biochemically analysed. The kinetic properties of the enzymes as well as the binding of TPP to the in vitro transcribed RNA of the proposed operons suggest that the vitamin B1 homeostasis in S. aureus is strongly regulated at transcriptional as well as enzymatic levels

Preface

Shows how glycol-engineering coupled to rapid recombinant protein production has facilitated the determination of glycoprotein structures Provides a review of the state of the art in glycoproteomics Written by experts in the field It has been predicted that nearly half of all human proteins are glycosylated indicating the significance of glycoproteins in human health and disease. For example, the glycans attached to proteins have emerged as important biomarkers in the diagnosis of diseases such as cancers and play a significant role in how pathogenic viruses gain entry into human cells. The study of glycoproteins has now become a truly proteomic science. In the last few years, technology developments including in silico methods, high throughput separation and detection techniques have accelerated the characterization of glycoproteins in cells and tissues. Glyco-engineering coupled to rapid recombinant protein production has facilitated the determination of glycoprotein structures key to exploring and exploiting their functional roles. Each chapter in this volume is written by experts in the field and together provide a review of the state of the art in the emerging field of glycoproteomics

Preface

Shows how glycol-engineering coupled to rapid recombinant protein production has facilitated the determination of glycoprotein structures Provides a review of the state of the art in glycoproteomics Written by experts in the field It has been predicted that nearly half of all human proteins are glycosylated indicating the significance of glycoproteins in human health and disease. For example, the glycans attached to proteins have emerged as important biomarkers in the diagnosis of diseases such as cancers and play a significant role in how pathogenic viruses gain entry into human cells. The study of glycoproteins has now become a truly proteomic science. In the last few years, technology developments including in silico methods, high throughput separation and detection techniques have accelerated the characterization of glycoproteins in cells and tissues. Glyco-engineering coupled to rapid recombinant protein production has facilitated the determination of glycoprotein structures key to exploring and exploiting their functional roles. Each chapter in this volume is written by experts in the field and together provide a review of the state of the art in the emerging field of glycoproteomics

Functional and structural proteomics of glycoproteins

Shows how glycol-engineering coupled to rapid recombinant protein production has facilitated the determination of glycoprotein structures Provides a review of the state of the art in glycoproteomics Written by experts in the field It has been predicted that nearly half of all human proteins are glycosylated indicating the significance of glycoproteins in human health and disease. For example, the glycans attached to proteins have emerged as important biomarkers in the diagnosis of diseases such as cancers and play a significant role in how pathogenic viruses gain entry into human cells. The study of glycoproteins has now become a truly proteomic science. In the last few years, technology developments including in silico methods, high throughput separation and detection techniques have accelerated the characterization of glycoproteins in cells and tissues. Glyco-engineering coupled to rapid recombinant protein production has facilitated the determination of glycoprotein structures key to exploring and exploiting their functional roles. Each chapter in this volume is written by experts in the field and together provide a review of the state of the art in the emerging field of glycoproteomics

Overview of a high-throughput pipeline for streamlining the production of recombinant proteins

Production of high quality protein is an essential step for both structural and functional studies. Throughput has increased in the past decade by the use of streamlined workflows with standard operating procedures and automation. In this chapter, we describe the Oxford Protein Production Facility (OPPF) pipeline for protein production, from conception, through vector construction, to expression and purification. Results from projects run in the OPPF demonstrate the value of using parallel expression screening of intracellular proteins in both E. coli and insect cells. Transient expression in Human Embryonic Kidney (HEK) cells is used exclusively for production of secreted glycoproteins. Protein purification and quality assessment are independent of the expression system and enable sample preparation to be simplified and streamlined

Overview of a high-throughput pipeline for streamlining the production of recombinant proteins

Production of high quality protein is an essential step for both structural and functional studies. Throughput has increased in the past decade by the use of streamlined workflows with standard operating procedures and automation. In this chapter, we describe the Oxford Protein Production Facility (OPPF) pipeline for protein production, from conception, through vector construction, to expression and purification. Results from projects run in the OPPF demonstrate the value of using parallel expression screening of intracellular proteins in both E. coli and insect cells. Transient expression in Human Embryonic Kidney (HEK) cells is used exclusively for production of secreted glycoproteins. Protein purification and quality assessment are independent of the expression system and enable sample preparation to be simplified and streamlined