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Title: Molecular genetic analysis of chemical-induced sporulation of Myxococcus xanthus
Author: Chatwin, Heather M.
ISNI:       0000 0001 3530 4635
Awarding Body: University of Warwick
Current Institution: University of Warwick
Date of Award: 1994
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Mutants resistant to glycerol-induction of sporulation were isolated from wild-type M. xanthus. The glycerol-resistant qlrA and alrB loci, previously mapped by Mx.8 transductions, were analysed by restriction mapping of clones and by complementation analysis. The location of the qlrA gene(s) was mapped to within a 2.2kb region, whilst the qlrB region proved very complex. The qlrA and qlrB gene products were reguired early in chemical-induced sporulation since two chemical-inducible lacZ fusions were not expressed in either qlrA or qlrB mutants during chemical-induction. Only a minority of the glycerol-resistant mutants were unable to undergo fruiting body sporulation. Complementation studies of the qlrA and qlrB regions confirmed that mutations in chemical-induced and fruiting body sporulation were not linked. This suggests that the induction pathways of chemical-induced sporulation and fruiting body sporulation share few common genes. Glycerol-resistant mutants were isolated from a non- motile strain, which is unable to form fruiting bodies. The majority of these mutants were able to form spores in the absence of fruiting bodies. Two mutants were unable to form spores. Isolating such mutants may provide a means of identifying truly sporulation-deficient mutants. Expression from the chemical-inducible isqB > lacZ fusion, identified previously in a promoter probe vector, was blocked in 24 different glycerol-resistant mutants. Hence, the gene product was reguired late in the chemical-induced sporulation pathway. The complete transcription unit was cloned and disruption of the region by the insertion of a tetracycline cassette demonstrated that the gene is not essential for chemical- induced or starvation-induced sporulation. Expression from a second chemical-inducible lacZ fusion, ÎÎDK4530, identified previously by random Tn£ lac insertion, was suppressed by amino acids in the growth media during chemical-induced sporulation and was blocked in both qlrA and qlrB mutants. Hence, expression of the gene product is dependent on both the qlrA+ and qlrB+ genes.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: QR Microbiology