Inadequate inhibition of host RNA polymerase restricts T7 bacteriophage growth on hosts overexpressing udk.
Overexpression of udk, an Escherichia coli gene encoding a uridine/cytidine kinase, interferes with T7 bacteriophage growth. We show here that inhibition of T7 phage growth by udk overexpression can be overcome by inhibition of host RNA polymerase. Overexpression of gene 2, whose product inhibits host RNA polymerase, restores T7 phage growth on hosts overexpressing udk. In addition, rifampicin, an inhibitor of host RNA polymerase, restores the burst size of T7 phage on udk-overexpressing hosts to normal. In agreement with these findings, suppressor mutants that overcome the inhibition arising from udk overexpression gain the ability to grow on hosts that are resistant to inhibition of RNA polymerase by gene 2 protein, and suppressor mutants that overcome a lack of gene 2 protein gain the ability to grow on hosts that overexpress udk. Mutations that eliminate or weaken strong promoters for host RNA polymerase in T7 DNA, and mutations in T7 gene 3.5 that affect its interaction with T7 RNA polymerase, also reduce the interference with T7 growth by host RNA polymerase. We propose a general model for the requirement of host RNA polymerase inhibition.
Qimron
Udi
U
Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA.
Kulczyk
Arkadiusz W
AW
Hamdan
Samir M
SM
Tabor
Stanley
S
Richardson
Charles C
CC
D017123:Bacteriophage T7 / Q000235:genetics / Q000254:growth & development*; D002468:Cell Physiological Phenomena; D012321:DNA-Directed RNA Polymerases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D048168:Escherichia coli K12 / Q000235:genetics* / Q000821:virology*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D016153:Genes, Suppressor; D054884:Host-Pathogen Interactions; D008958:Models, Molecular; D009154:Mutation; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D011401:Promoter Regions, Genetic; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D012293:Rifampin / Q000494:pharmacology; D014541:Uridine Kinase / Q000235:genetics / Q000378:metabolism*
D029968:Escherichia coli Proteins; D019384:Nucleic Acid Synthesis Inhibitors; D012097:Repressor Proteins; C120334:gene 2 product, bacteriophage T7; D014541:Uridine Kinase; D012321:DNA-Directed RNA Polymerases; D012293:Rifampin