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dc.contributor.advisor Moustafa, Ahmed
dc.contributor.advisor Ferreira, Ari El Bardisy, Hadeel Mansour 2014-02-19T13:34:36Z 2014-02-19T16:00:04Z 2014 Spring en 2014-02-19
dc.description.abstract Natural polyketide products are one of the major secondary metabolites produced among bacteria, fungi, and plants. They vary from flavonoids, pyrones, and stilbenes to phloroglucinols and resorcinols that are involved in important functions as antimicrobial activity, defense mechanisms and pigmentation. They are biosynthesized from acyl-CoA precursors by polyketides synthases (PKSs) that are categorized into 3 types: I, II and III. PKS type III is considered the simplest in its structure. It was believed that PKS type III was exclusively encoded by higher plants until the enduring efforts of bacterial genomes sequencing revealed the presence of more and more PKSs type III among them. There is an urge to investigate novel PKSs type III due to their promising polyketides of great biological and pharmaceutical advantages. This allowed metagenomic approaches to be a valuable tool to explore diverse environments for PKSs type III. Extreme environments as deep sea brine pools could probe unique natural polyketides capable of functioning in such conditions with valuable biotechnological and pharmaceutical applications. In this study, screening of the Lower Convective Layer (LCL) of Atlantis II (ATII) deep brine pool in the Red Sea was done. It identified sequences belonging to bacterial PKSs type III. A candidate encoding sequence was amplified from the environmental DNA. Functional annotations were assigned to the translated open reading frame including the conserved catalytic triad, domains, motifs and 3D modelling. Preliminary structural analysis showed well-fitted superimposition with the flowering plant Medicago sativa PKS type III crystal structure and predicted the interaction of the catalytic triad with the most common substrate malonyl-CoA. Further optimization of heterologous expression is required to investigate this isolated PKS type III functional activity. In an approach to gain better insights into the enzyme’s unresolved evolutionary origin, a comprehensive phylogenetic analysis was conducted. The analysis pinpoints the possible involvement of symbiotic bacterium Parachlamydia acanthamoebae in horizontal gene transfer events to eukaryotes. On the other hand, the sequence isolated from ATII brine pool was clustered in a clade with related PKSs type III sequences belonging to alpha-proteobacteria. Environmental assessment of PKSs type III abundance in ATII and nearby Discovery Deep (DD) brine pool revealed the presence of PKSs type III in ATII only, where most sequences were located in the LCL. This could be attributed to the high aromatic content within the brine as possible substrates for the enzyme. Based on these analyses, we could propose ATII microbial community as a unique source for natural polyketides. en
dc.description.sponsorship King Abdullah University of Science and Technology (KAUST), the participants in the spring 2010 expedition and lab colleagues for both collecting the samples and establishing the database. American University in Cairo (AUC) for awarding me a Laboratory fellowship en
dc.format.extent 83 p. en
dc.format.medium theses en
dc.language.iso en en
dc.rights Author retains all rights with regard to copyright. en
dc.subject Metagenomics en
dc.subject Red Sea en
dc.subject Evolution en
dc.subject Atlantis II brine pool en
dc.subject Structural modeling en
dc.subject Sequence en
dc.subject.lcsh Thesis (M.S.)--American University in Cairo en
dc.subject.lcsh Biotechnology -- Red Sea -- Egypt.
dc.subject.lcsh Microbiology -- Red Sea -- Egypt.
dc.subject.lcsh Metagenomics.
dc.subject.lcsh Molecular biology -- Red Sea -- Egypt.
dc.title Polyketide Synthase III isolated from uncultured deep-sea Proteobacterium from the Red Sea – functional and evolutionary characterization en
dc.type Text en
dc.subject.discipline Biotechnology en
dc.rights.access This item is available en
dc.contributor.department American University in Cairo. Biotechnology Graduate Program en
dc.description.irb American University in Cairo Institutional Review Board approval is not necessary for this item, since the research is not concerned with living human beings or bodily tissue samples. en
dc.contributor.committeeMember Moustafa, Ahmed
dc.contributor.committeeMember Bos, Arthur
dc.contributor.committeeMember Abou-Aisha, Khalid
dc.contributor.committeeMember El Gogary, Sawsan

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  • Theses and Dissertations [1707]
    This collection includes theses and dissertations authored by American University in Cairo graduate students.

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