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Title: Control of morphogenesis in Candida albicans
Author: Leng, P.
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 1999
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This thesis describes the cloning the characterisation of three C. albicans genes: CaTBP1 encoding the TATA-binding protein, CaRAD6 encoding a ubiquitin-conjugating (E2) enzyme, the CaALS7 encoding an agglutinin-like cell-surface protein. Finally, the ALS7 promoter has been discussed. The CaTBP1 open reading frame is 716 bp long and encodes a functional TATA Binding Protein (TBP) of 27 kDa. Comparison of the predicted amino acid sequences of TBPs from a range of organisms reveals at least 80% amino acid sequence identity in the C-terminal domain. CaTbp1p binds specifically to a TATA box in vitro, substitutes for the human TBP to activate basal transcription in vitro, and suppress the lethal Δspt15 (tbp1) mutation in S. cerevisiae. CaRAD6 contains a 573-nucleotide ORF with the potential to encode a 179 amino acid polypeptide with a molecular mass of 19.7 kDa. The CaRAD6 open reading frame is interrupted by two introns which both contain consensus splicing signal sequences. A comparison of the predicted amino acid sequences of Rad6 proteins from a range of organisms reveals strong conservation within their N-terminal domains (70% amino acid sequence identity). The CaRAD6 gene complements the UV sensitivity and defective UV mutagenesis of a S. cerevisiae rad6Δ mutant. RAD6 expression decreases during hyphal development in C. albicans. Elevated RAD6 expression levels inhibit hyphal development, and Rad6p depletion enhances hyphal growth. These effects are dependent on the Efg1p morphogenetic signalling pathway. Therefore, RAD6 is a negative regulator of hyphal development, revealing for the first time, a mechanistic link between ubiquitination and fungal morphogenesis. CaALS7 is a member of the ALS gene family encoding agglutinin-like cell surface proteins in C. albicans. The ALS7sequence has a 3141-nucleotide open reading frame with the potential to encode a 1047 amino acid polypeptide.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available