Isolation and Characterization of L-Deoxy-D-Xylulose 5-Phosphate Reductoisomerase
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UNIVERSITY OF HAWAII UBRAR,( Isolation and characterization of l-deoxy-D-xylulose 5-phosphate reductoisomerase (DXR) and putrescine N-methyl transferase (PMT) complementary deoxyribonucleic acid (eDNA) in Nicotiana benthamiana using cytoplasmic inhibition of gene expression (CIGE) technology A THESIS SUBMIl lED TO THE GRADUATE DMSION OF THE UNIVERSITY OF HAW AI'I IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE IN MOLECULAR BIOSCIENCES AND BIOENGINEERING AUGUST 2006 By J Malkeet Singh Thesis Committee: Monto Hiroshi Kumagai, Chairperson Dulal Bortbakur Winston Su We certify that we have read this thesis and that, in our opinion, it is satisfactory in scope and quality as a thesis for the degree of Master of Science in Molecular Biosciences and Bioengineering. THESIS COMMlITEE ii ACKNOWLEDGEMENTS This research was funded by U.S. Department of Agriculture (USDA; TSTAR Gram: Patented research materials were kindly provided by Dr. Monto Kumagai and Dr. Guy della-Cioppa and Large Scale Biology Corpolation. Sincere thanks to all who have rendered encouragement and help: Dr. Monto Kumagai, Alain Ogura, Aaron Lani, Jessica Proberts, Naomi, Leah Tedder. Jennifer Busto, Rujunko Pugh, Manning Taite, Beth Irikura, Jason Dexter, Joanne Kurosawa, Anti Vesnefski, Dr. Dulal Bortbakur and Dr. Winston Suo Also to all family members and friends for their kindness and wisdom and especially to God who is sovereign over all. iii TABLE OF CONTENTS Aclmowledgements ..................................................................................iii List of Table ......................................................................................... vii . f· ... List 0 Figures .......................................................................................V111 Chapter 1. Literature Review .........................................................................1 1.1 Vual Vectors ..................................................................................... 1 1.1.1 The Use ofPlant Vual Vectors .............................................................. 1 1.1.2 Tobacco Mosaic VIrUS Vectors ............................................................. 3 1.1.3 Vual Vector Design Construct ............................................................ .4 1.2 Nicotiona benthamtana: A Model Plant for Functional Genomics ...................... 7 1.3 Safety and ContAinment Issues ................................................................ 8 1.4 Post Translational Gene Silencing (PTGS) ..................................................9 1.5 Metabolic Engineering ....................................................................... 13 1.6 Isoprenoid Biosynthesis and DXR. ........................................................... 14 1.7 Alkaloid biosynthesis and PMT ............................................................. .16 1.8 Aim ............................................................................................. 16 Chapter 2. Introduction .............................................................................. 18 2.1 DXR. and PMT ................................................................................. 18 2.1.1 DXR. in the MEP Pathway ................................................................ 18 2.1.2 PMT in the Alkaloid Pathway ............................................................ 20 iv Chapter 3. Materials and Methods ................................................................ 21 3.1 Bacterial Strains and Plants ..................................................................21 3.2 Recombinant VIral vector Assembly ...................................................... 21 3.3 eDNA Expression and Characterization ....................................................24 3.4 Plant RNA Isolation and Analysis ........................................................... 25 3.5 Microarray ....................................................................................... 26 3.5.1 Labeling and Hybridization for eDNA Microarrays ................................... 26 3.5.2 Microarray Scanning ....................................................................... 27 Chapter 4. Results ................................................................................... 28 4.1 DXR and PMT Cloning and Characterization .............................................28 4.1.1lsolation and Annotation ofN. benthamiana DXR. ................................... 28 4.1.2 DXR Sequeru:e Analysis .................................................................. 30 4.2 Construction of Recombinant VIral Vectors ...............................................33 4.3 RT PCR for the Verification ofInserts .....................................................35 4.4 Applications ofCIGE .........................................................................35 4.4.1 Mimicking Herbicide Effects inN. benthamiana ......................................35 4.4.2 Manipulation of Alkaloid Production in N. benthamiana .............................38 Chapter 5. Discussion ............................................................................... 39 5.1 Mimicking Herbicide Treatment ............................................................39 5.2 Manipulation of Biochemical Pathways ................................................... 40 5.3 Gene Silencing Systems ...................................................................... .43 v 5.4 DXRforDrugDesign ........................................................................ .45 5.4.1 Functioual Conservation across Plant, Protoman and Bacterial DXR ............ .45 5.4.2 Future Goals and Potential ofDXR Research ......................................... 47 5.5 References ...................................................................................... 50 vi USTOFTABLE 1 Genes in Putrescine related pathway ......................................................... 38 vii LIST OF FIGURES I The PTGS system ................................................................................ 12 2 Screening of eDNA libraries fur gene functions ............................................ 14 3 DXR in tile IPP biosynthesis pathway ...................................................................... 19 4 PMT in the nicotine biosynthesis pathway .................................................20 5 General flow chart of tile cloning of genes ................................................. 23 6 N. benthamiana DXR open reading frame .................................................. 29 7 Multiple alignment of plant, E.colt and P.jalcipan.nn meR.............................. 31 8 Recombinant viral vectors ..................................................................... 34 9 RTPCR........................................................................................... 35 10 Mimicking the effects of herbicides .......................................................... 37 11 OXR+. PMT- and GFP plants ............................................................... .42 12 Alignment between N. beothamiana OXR and E. coli DXR consensus sequence ........................................................................................ 46 13 N. benthamina (NBOXR) and P. falciparum (PFDXR) double alignment .............46 14 Molecular model ofthe conserved domain ofOXR...................................... .48 15 Flow chart of functional studies ...............................................................49 viii Chapter 1 Uterature Review 1.1 Viral Vectors 1.1.1 The Use of Plant Viral Vectors Transgenic crops have played a role in the production of pharmaceuticals and other valuable biological molecules. A more efficient strategy has involved by inoculating non-transgenic plants with virus-based vectors that carry foreign genes. As research progressed in the development of transgenic plants, it was discovered that plants have a built-in post-transcriptional gene silencing mechanism [8, 29]. The introduction of a gene homologous to an endogenous plant gene was found to cause a decrease in expression of both genes sucb as sbown in the case of controlling gene expression in transgenic petunia flowers [37]. This effect was also observed in response to homologous genes from viruses, implicating the gene silencing mechanism as a possible defense mechanism against viral genes [1]. With the development of infectious DNA clones, single-stranded RNA plant viruses have become key players in gene function discovery, metabolic engineering, and biomanufacturing. Viral expression vectors provide epigenetic expression of foreign sequences throughout infected plants, leading to gain-or loss of function phenotypes due to overexpression or cytoplasmic inhibition of gene expression. 1 Plant viruses are powerful transfection tools in molecular farming, producing pure, properly folded and gIycosylated proteins in plants faster and more economically than other expression systems [12, 13]. They are a highly desirable alternative to transgenic systems that require protracted periods to transform and regenerate whole plants, and that have variation in the expression levels of heterologous proteins. In transgenic systems, once a particular construct is inserted into the plant genome, it may take several crosses to establish a stable line in an elite cultivar. In contrast, plant viral vectors employed in the large-scale production of therapeutic drugs in greenhouse and field-grown crops directly yield high levels of foreign protein due to the rapid rate of viral