Alkaline phosphatase fusions in the study of cell division genes.

Alkaline phosphatase fusions have been used to analyse plasmid- or phage-carried genes from the two-minute region of the Escherichia coli chromosome. These studies have revealed the following: 1) Bacteriophage lambda carries two genes for cell envelope proteins, lom and bor, that are expressed in lysogens and probably contribute to the pathogenicity of its E. coli host. 2) The ftsQ and ftsl gene products are integral proteins of the cytoplasmic membrane with small cytoplasmic domains and large periplasmic domains. 3) The ftsQ and ftsl gene products are made in very small amounts, on the order of 25 molecules per cell. 4) The ftsQ gene product is essential for cell growth and is required throughout the formation of the cell septum. 5) An open reading frame just upstream from ftsl, thought to be involved in cell division, is expressed and probably codes for a cytoplasmic membrane protein.