Gill, Deborah R. (1986) Characterisation of a novel cell division operon in "E. coli" K-12. PhD thesis, University of Warwick.

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Abstract

Several genes essential for morphogenesis of E. coli are located in the 76-minute region of the chromosome. These include the cell division genes, ftsE and ftsS, and the heat shock control gene rpoH(htpR). A λ transducing phage λGS22, which complemented mutations in ftsE and fCsS but not htpR, was used to investigate the transcriptional organisation of the genes in this region. A 4.5 kb HindIII fragment was subcloned from λpGS22 into multicopy plasmid vectors, and was shown to complement mutations in ftsE. The DNA sequence of this fragment revealed four major open reading frames (ORFs), three of which were transcribed in the same direction and showed several features characteristic of an operon. Using transposon mutagenesis and deletion analysis, the second gene in this operon was determined to be ftsE. The previously unassigned mutation carried by strain OV32 was cloned and shown to map in the third gene in the operon. This novel cell division gene was designated ftsX. Both the ftsE and ftsX genes were shown to be co-transcribed. The fts gene products were identified in maxicell experiments. Interestingly, the 0RF1 (ftsY) gene product was twice the predicted relative molecular mass. In vitro and in vivo insertion mutagenesis proved conclusively that ftsY encoded this protein. All four proteins were localised to the inner membrane of the cell, although some FtsE and FtsY protein was also found in the cytoplasmic fraction. It is possible that the proteins are associated with each other in the membrane as part of the 'septalsome'. The FtsE protein is particularly interesting because it shows strong homology with a small family of inner membrane-located proteins known to have nucleotide binding activity. The proteins also share strong homology at another separate domain of unknown function.

In conclusion, a novel cell division operon of three genes has been identified, and sequence, protein and localisation studies have indicated that the proteins could be associated with each other in the membrane to function in cell division.

Item Type:	Thesis (PhD)
Subjects:	Q Science > QH Natural history Q Science > QR Microbiology
Library of Congress Subject Headings (LCSH):	Escherichia coli -- Genetics, Operons, Cell division
Official Date:	September 1986
Dates:	Date Event September 1986 UNSPECIFIED
Institution:	University of Warwick
Theses Department:	Department of Biological Sciences
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Salmond, George
Sponsors:	Science and Engineering Research Council (Great Britain)
Extent:	xvii, 276 leaves : illustrations
Language:	eng

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