Disease relevance of letA

• The letA (ccdA) and letD (ccdB) genes of F plasmid contribute to stable maintenance of the plasmid in Escherichia coli cells; a product of the latter has a lethal effect on the host cell and that of the former neutralizes functions of the letD [1].
• The letD gene product acts to inhibit cell division of the host bacteria and to induce prophages in lysogenic bacteria, whereas the letA gene product acts to suppress the activity of the letD gene product [2].
• The LetE protein enhances expression of multiple LetA/LetS-dependent transmission traits by Legionella pneumophila [3].

High impact information on letA

• The letD gene product acts to inhibit partitioning of chromosomal DNA and cell division by inhibiting DNA gyrase activity, whereas the letA gene product acts to reverse the inhibitory activity of the letD gene product [4].
• The letA (ccdA) and letD (ccdB) genes, located just outside the sequence essential for replication of the F plasmid, apparently contribute to stable maintenance of the plasmid [5].
• The letA and letD cistrons were mapped on the 42.84-43.35 F (BamHI- XmaI ) segment and the 43.07-43.6 F (HincII-PstI) segment, respectively, and are presumed to correspond to the first (43.04-43.26 F) and second (43.26-43.57 F) open reading frames, respectively, which were found in this region by nucleotide sequencing [2].
• When plasmid DNA replication is completed, synthesis of LetA protein (and also LetD protein) takes place and the LetA protein synthesized acts to suppress the activity of LetD protein and make the cell ready for cell division [2].

Biological context of letA

• The letD gene product acts to inhibit partitioning of chromosomal DNA and cell division of the host bacteria, whereas the letA gene product acts to suppress the activity of the letD gene product [5].
• Two cistrons were found in this region and they were designated letA and letD (an abbreviation for lethal mutation) [2].

Analytical, diagnostic and therapeutic context of letA

• Rejuvenation of the inactivated GyrA protein by the LetA protein was achieved in vitro, and mechanisms governing this process were examined using the purified proteins [6].

References