Bollivar, Faculty Advisor, David

Clauson, Cheryl

Digital Commons @ Illinois Wesleyan University

Illinois Wesleyan UniversityDigital Commons @ IWUJohn Wesley Powell Student ResearchConference 2003, 14th Annual JWP ConferenceApr 12th, 9:00 AM - 10:00 AMPorphobilinogen Synthase in the HemeBiosynthesis Pathway of R. CapsulatusCheryl ClausonIllinois Wesleyan UniversityDavid Bollivar, Faculty AdvisorIllinois Wesleyan UniversityFollow this and additional works at: http://digitalcommons.iwu.edu/jwprcThis Event is brought to you for free and open access by The Ames Library, the Andrew W. Mellon Center for Curricular and FacultyDevelopment, the Office of the Provost and the Office of the President. It has been accepted for inclusion in Digital Commons @ IWU bythe faculty at Illinois Wesleyan University. For more information, please contact digitalcommons@iwu.edu.©Copyright is owned by the author of this document.Cheryl Clauson and David Bollivar, Faculty Advisor, "Porphobilinogen Synthase in the Heme Biosynthesis Pathway of R.Capsulatus" (April 12, 2003). John Wesley Powell Student Research Conference. Paper 42.http://digitalcommons.iwu.edu/jwprc/2003/posters/42THE JOHN WESLEY POWELL STUDENT RESEARCH CONFERENCE - APRJL 2003 Poster Presentation PII PORPHOBILINOGEN SYNTHASE IN THE HEME BIOSYNTHESIS PATHWAY OF R. CAPSULATUS Cheryl Clauson and David Bollivar* Department of Biology, Illinois Wesleyan University Porphobilinogen synthase is an enzyme that is essential to the biosynthesis of tetrapyrroles, such as heme and chlorophyll, in organisms from bacteria to humans. The PBGS of purple non-sulfur bacteria of the genus Rhodobacter are thought to be unique in that they do not require zinc in the active site of the enzyme and that the enzyme is also not stimulated by the presence of magnesium, as it is in plants and the bacterium Escherichia coli. The hemE gene from Rhodobacter capsulatus was sequenced, and showed great sequence similarity to the related species Rhodobacter sphaeroides. The hemE gene was cloned into an expression plasmid to create an expression strain of E. coli to obtain large quantities of the PBGS protein. The protein was purified from the E. coli in milligram quantities and is in the process of being crystallized to determine the three­dimensional structure. Activity assays have shown that zinc, while not required in the active site, does stimulate the activity. Potassium also stimulates the enzyme activity. Magnesium, which has been shown to stimulate in some species, does not seem to stimulate the R. capsulatus PBGS. More activity assays are planned and include p­mercaptoethanol, and pH tests to find the optimal pH for the enzyme activity. Other work includes making a knockout mutation of the PBGS gene in R. capsulatus as there is evidence for viable mutants in Rhodobacter sphaeroides, which is significant since heme is required for life and this pathway is the only known mechanism for making heme 

Porphobilinogen Synthase in the Heme Biosynthesis Pathway of R. Capsulatus

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Porphobilinogen Synthase in the Heme Biosynthesis Pathway of R. Capsulatus

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