Cloning and characterization of triterpene synthases

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dc.contributor.advisorMatsuda, Seiichi P. T.en_US
dc.creatorHerrera, Jennifer Bridgette Reynaen_US
dc.date.accessioned2009-06-04T06:35:44Zen_US
dc.date.available2009-06-04T06:35:44Zen_US
dc.date.issued2000en_US
dc.description.abstractOxidosqualene cyclases are a group of enzymes that cyclize 2,3-oxidosqualene to any of over 80 triterpene skeletons. Sequence correlation suggests these enzymes share a common overall structure and subtle changes in active site residues are responsible for differences in the structure of the cyclization product. Further characterization of conserved residues has lead to a better understanding of the mechanisms through which regio- and stereo-selective cyclization occurs. This work has resulted in the cloning of three new oxidosqualene cyclases. By cloning triterpene synthases from far-diverged organisms, new sequence data has been added for correlation and has provided new information regarding evolution of the enzymes from a common ancestor. Arabidopsis thaliana lupeol synthase was cloned and the full-length cDNA expressed in yeast. Degenerate PCR primers designed from regions of highly conserved sequence were used to clone cycloartenol synthase and a presently uncharacterized triterpene synthase from an Abies magnifica library. Newly obtained and previously published sequence data has been used to identify residues that may correlate with catalytic activity. Site-directed mutagenesis has been performed on Arabidopsis thaliana cycloartenol synthase resulting in enzymes with different product distributions. In addition to producing cycloartenol, these mutant proteins were shown to produce a range of new triterpene alcohols, including monocyclic alcohols and a previously unknown triterpene skeleton. Sequence information as well as the mechanistic information learned from the analysis of mutant protein products has come together to reveal a complex relationship between structure and function of triterpene synthases. Using techniques of molecular biology as well as analytical and organic chemistry, aspects of the nature of oxidosqualene cyclases in terms of the mechanisms of transformation, evolution and physiological significance are presented.en_US
dc.format.extent96 p.en_US
dc.format.mimetypeapplication/pdfen_US
dc.identifier.callnoTHESIS CHEM. 2000 HERRERAen_US
dc.identifier.citationHerrera, Jennifer Bridgette Reyna. "Cloning and characterization of triterpene synthases." (2000) Diss., Rice University. <a href="https://hdl.handle.net/1911/19506">https://hdl.handle.net/1911/19506</a>.en_US
dc.identifier.urihttps://hdl.handle.net/1911/19506en_US
dc.language.isoengen_US
dc.rightsCopyright is held by the author, unless otherwise indicated. Permission to reuse, publish, or reproduce the work beyond the bounds of fair use or other exemptions to copyright law must be obtained from the copyright holder.en_US
dc.subjectBiochemistryen_US
dc.subjectOrganic chemistryen_US
dc.titleCloning and characterization of triterpene synthasesen_US
dc.typeThesisen_US
dc.type.materialTexten_US
thesis.degree.departmentChemistryen_US
thesis.degree.disciplineNatural Sciencesen_US
thesis.degree.grantorRice Universityen_US
thesis.degree.levelDoctoralen_US
thesis.degree.nameDoctor of Philosophyen_US
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