Alkhder, Duha (2022) Study of the mechanism of action and biosynthesis of microbial secondary metabolites. PhD thesis, University of Warwick.

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Abstract

Fungi and bacteria are wealthy sources of bioactive compounds. IPS (3,5-Dihydroxy-4-isopropyl-trans-stilbene) is a natural bacterial stilbene with diverse biological and pharmacological properties, and it is being used commercially to treat psoriasis. However, its mechanism of action remains unclear. Thus, the work described here aimed at elucidating the mechanism of action of IPS in yeast and filamentous fungi. Previous analyses identified 19 genes as being potentially involved in the pathways targeted by IPS in yeast S. cerevisiae W303. Chemical genetic profiling approaches applied on yeast deletion collection pool revealed that the strain S. cerevisiae dis3::KanMX showed the most growth reduction in presence of IPS suggesting that the gene DIS3 is a target of IPS. This was further confirmed by the overexpression of the gene DIS3 which resulted in the strains becoming more tolerant to high concentrations of IPS. High-throughput molecular analyses including proteomic analysis and RNA sequencing performed on S. cerevisiae W303 wild-type and S. cerevisiae dis3::KanMX strains suggested that the yeast has an obvious response to IPS exposure, reflected in changes in the transcriptome and proteome. Moreover, IPS bioactivity against A. oryzae NSAR1 is reported here for the first time.

Furthermore, efforts to expand the understanding of the early steps of pleurotin biosynthesis were also described. Pleurotin is a fungal meroterpenoid compound discovered from Hohenbuehelia grisea and reported to exhibit pharmacologic activities as a promising anticancer drug, as well as antimicrobial activities against bacteria and fungi. A potential gene cluster responsible for pleurotin synthesis was identified using DNA sequencing and comparative transcriptomic approaches. To shed the light on the detailed biosynthetic mechanism of pleurotin, reconstitution of its biosynthetic machinery was attempted in Aspergillus oryzae NSAR1. Stepwise introduction of the genes potentially involved in the putative BGC suggested the potential accumulation of several intermediates from the biosynthetic route, indicating the involvement of these genes within pleurotin biosynthesis.

Item Type:	Thesis (PhD)
Subjects:	Q Science > QD Chemistry Q Science > QP Physiology Q Science > QR Microbiology
Library of Congress Subject Headings (LCSH):	Microbial metabolites, Bioactive compounds, Stilbene, Psoriasis -- Treatment
Official Date:	September 2022
Dates:	Date Event September 2022 UNSPECIFIED
Institution:	University of Warwick
Theses Department:	Warwick Medical School
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Waterfield, Nicholas R. ; Alberti, Fabrizio
Sponsors:	University of Warwick ; Council for At-Risk Academics
Format of File:	pdf
Extent:	xviii, 222 pages : illustrations (some colour)
Language:	eng

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