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30
and the PT domains in these enzymes catalyze the entire cyclization procedure. The enzymes cyclize the polyketide via C6-C11/C4-C13 regioselectivity. AptA is an example of Group V. Experiments were carried out to verify if the AptA-PT domain catalyzes the cyclization of the first, second and third ring. The regioselectivity of Group V PT domains was verified for its generalization by carrying out the heterologous combinations of target PTs with minimal NR-PKSs.[17]
4.2 TE domain:
Studies on the Pks that synthesizes aflatoxin B1, PksA, showed that the KS, MAT and ACP domain connect with the PT domain to extend the hexanoyl starter unit and subsequently carry out cyclization. [19] The results showed that different products were generated in the presence and absence of the TE domain. In the absence of the TE domain a C-O bond was formed to give a pyrone while the presence of the domain gave a C-C bond to give the Claisen condensation product noranthrone. The Claisen cyclase (CLC) behavior for nonreducing fungal PKS TE domains was first observed in the work of Ebizuka, Fujii, and Watanabe, in which the normal Claisen product was diverted to its isomeric pyrone when the TE/CLC domain was either truncated or inactivated by site-specific
Object Description
| Title | Fungal polyketides -- Review of recent findings |
| Author | Jain, Sofina M. |
| Author email | sofinaja@usc.edu; sofinajain27@gmail.com |
| Degree | Master of Science |
| Document type | Thesis |
| Degree program | Pharmacy / Pharmaceutical Sciences |
| School | School of Pharmacy |
| Date defended/completed | 2011-05-04 |
| Date submitted | 2011 |
| Restricted until | Unrestricted |
| Date published | 2011-05-05 |
| Advisor (committee chair) | Wang, Clay C. C. |
| Advisor (committee member) |
Okamoto, Curtis Toshio Shen, Wei-Chiang |
| Abstract | Fungal polyketides are a group of bioactive compounds which have found use in humans as anti-cholesterol, anti-cancer and antibiotic agents. These are synthesized by a group of enzymes called the polyketide synthases (PKSs) which are found in fungi as well as bacteria. PKSs are classified as type I, II and III. All fungal PKSs are type I iterative polyketide synthases which means they use a set of catalytic functions by a group of active domains in repetitive cycles to give the end product. Type I enzymes contain multidomains that catalyze a set of reactions.; The minimal PKS contains the domains ketosynthase (KS), acyltransferase (AT) and acyl carrier protein (ACP). The three types of PKSs are non-reduced polyketide synthases (NR-PKSs), highly-reduced polyketide synthases (HR-PKSs) and partially-reduced polyketide synthases (PR-PKSs). This classification is another form separate from type I, II and III. This paper discusses the recent research into further details of the SAT, PT and TE domain of the NR-PKSs and also recent advances in the HR-PKSs. This paper will also discuss the role of NADPH, SAM and CON domain in the HR-PKSs. We will also discuss the two off-loading mechanism of HR-PKSs that were seen in recent papers. While little research is done on PR-PKSs, NR-PKS and HR-PKS are extensively being worked on.Recent findings have brought us a step closer to the domains of the PKSs and promise us a better clearer understanding of this complex multidomain entity. |
| Keyword | fungal polyketides; HR-PKS; NR-PKS; PT domain; SAT domain; TE domain |
| Language | English |
| Part of collection | University of Southern California dissertations and theses |
| Publisher (of the original version) | University of Southern California |
| Place of publication (of the original version) | Los Angeles, California |
| Publisher (of the digital version) | University of Southern California. Libraries |
| Provenance | Electronically uploaded by the author |
| Type | texts |
| Legacy record ID | usctheses-m3914 |
| Contributing entity | University of Southern California |
| Rights | Jain, Sofina M. |
| Repository name | Libraries, University of Southern California |
| Repository address | Los Angeles, California |
| Repository email | cisadmin@lib.usc.edu |
| Filename | etd-jain-4552 |
| Archival file | uscthesesreloadpub_Volume40/etd-jain-4552.pdf |
Description
| Title | Page 36 |
| Contributing entity | University of Southern California |
| Repository email | cisadmin@lib.usc.edu |
| Full text | 30 and the PT domains in these enzymes catalyze the entire cyclization procedure. The enzymes cyclize the polyketide via C6-C11/C4-C13 regioselectivity. AptA is an example of Group V. Experiments were carried out to verify if the AptA-PT domain catalyzes the cyclization of the first, second and third ring. The regioselectivity of Group V PT domains was verified for its generalization by carrying out the heterologous combinations of target PTs with minimal NR-PKSs.[17] 4.2 TE domain: Studies on the Pks that synthesizes aflatoxin B1, PksA, showed that the KS, MAT and ACP domain connect with the PT domain to extend the hexanoyl starter unit and subsequently carry out cyclization. [19] The results showed that different products were generated in the presence and absence of the TE domain. In the absence of the TE domain a C-O bond was formed to give a pyrone while the presence of the domain gave a C-C bond to give the Claisen condensation product noranthrone. The Claisen cyclase (CLC) behavior for nonreducing fungal PKS TE domains was first observed in the work of Ebizuka, Fujii, and Watanabe, in which the normal Claisen product was diverted to its isomeric pyrone when the TE/CLC domain was either truncated or inactivated by site-specific |
