The mutation that makes Escherichia coli resistant to lambda P gene-mediated host lethality is located within the DNA initiator Gene dnaA of the bacterium.
Earlier, we reported that the bacteriophage lambda P gene product is lethal to Escherichia coli, and the E. coli rpl mutants are resistant to this lambda P gene-mediated lethality. In this paper, we show that under the lambda P gene-mediated lethal condition, the host DNA synthesis is inhibited at the initiation step. The rpl8 mutation maps around the 83 min position in the E. coli chromosome and is 94 % linked with the dnaA gene. The rpl8 mutant gene has been cloned in a plasmid. This plasmid clone can protect the wild-type E. coli from lambda P gene-mediated killing and complements E. coli dnaAts46 at 42 degrees C. Also, starting with the wild-type dnaA gene in a plasmid, the rpl-like mutations have been isolated by in vitro mutagenesis. DNA sequencing data show that each of the rpl8, rpl12 and rpl14 mutations has changed a single base in the dnaA gene, which translates into the amino acid changes N313T, Y200N, and S246T respectively within the DnaA protein. These results have led us to conclude that the rpl mutations, which make E. coli resistant to lambda P gene-mediated host lethality, are located within the DNA initiator gene dnaA of the host.
Datta
Indrani
I
Department of Biochemistry, Bose Institute, Acharya J. C. Bose Birth Centenary Building, P-1/12, CIT Scheme VII M, Calcutta 700 054, India.
Banik-Maiti
Sarbani
S
Adhikari
Lopa
L
Sau
Subrata
S
Das
Niranjan
N
Mandal
Nitai Chandra
NC
D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D010582:Bacteriophage lambda / Q000235:genetics* / Q000472:pathogenicity; D002876:Chromosomes, Bacterial; D004261:DNA Replication; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D024881:Drug Resistance, Bacterial; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics*; D005804:Genes, Lethal; D016296:Mutagenesis; D009154:Mutation / Q000235:genetics*; D010957:Plasmids; D013696:Temperature
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; C066312:DnaA protein, Bacteria