Genetics - Theses

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Start date: 1990 × End date: 1999 × Subject: Amidases -- Genetic aspects ×

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    Comparison of amidase genes in Aspergillus species
    Sharp, Julie Anne. (University of Melbourne, 1998)
    A study was undertaken to identify evolutionally conserved sequences within the acetamidase gene regulatory region across Aspergillus species which may define binding sites for transcriptional control regulatory proteins. Six amdS genes were cloned and characterised from five Aspergillus species and compared to A. nidulans and A. oryzae amdS genes. The amdS gene from A. echinulatus was predicted to be non functional due to a termination codon after amino acid 23. A proposed amdS pseudogene was identified in A. ustus. In this species two genes with amdS homology were identified, one with acetamidase activity and one lacking detectable amidase activity. A comparison of the Aspergillus spp. amdS coding region sequences revealed a very high level of conservation. The hydrolysis of amides by the Aspergillus spp. amdS genes was studied by heterologous gene expression in A. nidulans. Acetamide, propionamide, valeramide and butyramide were found to be substrates for A. ustus and A. unguis AmdS. A comparison of the transcriptional regulatory controls governing expression of Aspergillus spp. amdS and A. nidulans amdS genes was performed by heterologous expression of amdS genes fused to a reporter gene. Only some of the transcriptional control pathways regulating A. nidulans amdS were shown to regulate the different Aspergillus spp. amdS genes. During the course of this study, an amidase gene family was discovered in Aspergillus. The identification, cloning, functional characterisation, regulation and evolution of two members of the amidase gene family, gmdB (encoding general amidase B) and gmdC (encoding general amidase C) are described. Four gmdB genes were studied from four Aspergillus species and one gmdC gene was studied in A. nidulans. Substrates for the GmdB enzymes are valeramide, hexanamide and tyrosine amide, however substrate preferences for amide hydrolysis by the different GmdB enzymes differ between Aspergillus species. Transcriptional regulation of gmdB, determined by heterologous gene expression of reporter constructs in A. nidulans is not conserved between the species. The amidase family of genes comprising amdS, gmdB and gmdC is highly conserved in sequence and gene structure and suggests evolution from a common ancestor.
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    Comparison of amidase genes in Aspergillus species
    Sharp, Julie Anne. (University of Melbourne, 1998)
    A study was undertaken to identify evolutionally conserved sequences within the acetamidase gene regulatory region across Aspergillus species which may define binding sites for transcriptional control regulatory proteins. Six amdS genes were cloned and characterised from five Aspergillus species and compared to A. nidulans and A. oryzae amdS genes. The amdS gene from A. echinulatus was predicted to be non functional due to a termination codon after amino acid 23. A proposed amdS pseudogene was identified in A. ustus. In this species two genes with amdS homology were identified, one with acetamidase activity and one lacking detectable amidase activity. A comparison of the Aspergillus spp. amdS coding region sequences revealed a very high level of conservation. The hydrolysis of amides by the Aspergillus spp. amdS genes was studied by heterologous gene expression in A. nidulans. Acetamide, propionamide, valeramide and butyramide were found to be substrates for A. ustus and A. unguis AmdS. A comparison of the transcriptional regulatory controls governing expression of Aspergillus spp. amdS and A. nidulans amdS genes was performed by heterologous expression of amdS genes fused to a reporter gene. Only some of the transcriptional control pathways regulating A. nidulans amdS were shown to regulate the different Aspergillus spp. amdS genes. During the course of this study, an amidase gene family was discovered in Aspergillus. The identification, cloning, functional characterisation, regulation and evolution of two members of the amidase gene family, gmdB (encoding general amidase B) and gmdC (encoding general amidase C) are described. Four gmdB genes were studied from four Aspergillus species and one gmdC gene was studied in A. nidulans. Substrates for the GmdB enzymes are valeramide, hexanamide and tyrosine amide, however substrate preferences for amide hydrolysis by the different GmdB enzymes differ between Aspergillus species. Transcriptional regulation of gmdB, determined by heterologous gene expression of reporter constructs in A. nidulans is not conserved between the species. The amidase family of genes comprising amdS, gmdB and gmdC is highly conserved in sequence and gene structure and suggests evolution from a common ancestor.