Analysis of six new genes encoding lysis proteins and coat proteins in Escherichia coli group A RNA phages.

Group A RNA phages consist of four genes-maturation protein, coat protein, lysis protein and replicase genes. We analyzed six plasmids containing lysis protein genes and coat protein genes of Escherichia coli group A RNA phages and compared their amino acid sequences with the known proteins of E. coli(group A), Pseudomonas aeruginosa(PP7) RNA phages and Rg-lysis protein from Qbeta phage.

A cryptic lysis gene near the start of the Qbeta replicase gene in the +1 frame.

The maturation/lysis (A2) protein encoded by the group B single-stranded RNA bacteriophage Qbeta mediates lysis of host Escherichia coli cells. We found a frameshift mutation in the replicase (beta-subunit) gene of Qbeta cDNA causes cell lysis. The mutant has a single base deletion 73 nucleotides (nt) 3' from the start of the replicase gene with consequent translation termination at a stop codon 129-131 nt further 3'.

Various morphological aspects of Escherichia coli lysis by two distinct RNA bacteriophages.

Transmission electron micrographs of Escherichia coli cells induced by cloned lysis genes from RNA bacteriophages GA (group A-II) and SP (group B-IV) revealed various morphological aspects of intermediates of lysing cells. Cells induced by the SP lysis gene became stretched and also tapered in shape and fragmentation of parts of the cells had also occurred. Cells induced by the GA lysis gene showed many ballooning structures on the cell surfaces and others leaked material through the cell wall.