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Title: Genomic organisation and characterisation of the ISG65 genes in Trypanosoma brucei
Author: Crow, M. S.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2000
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The surface of bloodstream form Trypanosoma brucei is covered by a dense coat of variant surface glycoprotein (VSG). However, distributed over the entire cell surface within the VSG monolayer, is a much less abundant invariant surface glycoprotein 65 (ISG65) of unknown function. The genomic organisation of ISG65 has been investigated. ISG65 is encoded by multiple genes arranged in tandem at a single locus with a polymorphism, due to an insertion, in one of the alleles. Preliminary results suggest that the total number of ISG65 genes is strain dependent. Analysis of sequence data immediately downstream of the ISG65 cluster identified two ORFs on the opposite DNA strand to ISG65, indicating that ISG65 is at the end of a transcription unit. Interestingly, comparison of the predicted amino acid sequences of individual ISG65 genes has revealed the presence of different isoforms of ISG65. ISG65 is expressed predominantly (if not exclusively) in the mammalian bloodstream form stage of T. brucei. In accordance with this, ISG65 mRNA is present in bloodstream forms but is barely detectable in cultured procyclic cells. In trypanosomes, due to the polycistronic nature of transcription, post-transcriptional mechanisms must play a major role in modulating the expression of individual genes. Indeed, incubation of procyclic cells with protein synthesis inhibitors led to an accumulation of ISG65 mRNA, suggesting a link between translation and ISG65 mRNA stability.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available