Exclusion of glucosyl-hydroxymethylcytosine DNA containing bacteriophages is overcome by the injected protein inhibitor IPI*.
The Escherichia coli isolate CT596 excludes infection by the Myoviridae T4 ip1(-) phage that lacks the encapsidated IPI* protein normally injected into the host with the phage DNA. Screening of a CT596 genomic library identified adjacent genes responsible for this exclusion, gmrS (942 bp) and gmrD (708 bp) that are encoded by a cryptic prophage DNA. The two genes are necessary and sufficient to confer upon a host the ability to exclude infection by T4 ip1(-) phage and other glucosyl-hydroxymethylcytosine (glc-HMC) Tevens lacking the ip1 gene, yet allow infection by phages with non-glucoslyated cytosine (C) DNA that lack the ip1 gene. A plasmid expressing the ip1 gene product, IPI*, allows growth of Tevens lacking ip1 on E. coli strains carrying the cloned gmrS/gmrD genes. Members of the Teven family carry a diverse and, in some cases, expanded set of ip1 locus genes. In vivo analysis suggests a family of gmr genes that specifically target sugar-HMC modified DNA have evolved to exclude Teven phages, and these exclusion genes have in turn been countered by a family of injected exclusion inhibitors that likely help determine the host range of different glc-HMC phages.
Bair
Catherine L
CL
Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201-1503, USA.
Rifat
Dalin
D
Black
Lindsay W
LW
D044503:5-Methylcytosine / Q000031:analogs & derivatives; D000595:Amino Acid Sequence; D017122:Bacteriophage T4 / Q000378:metabolism; D001435:Bacteriophages / Q000378:metabolism*; D001483:Base Sequence; D036022:Capsid Proteins / Q000378:metabolism*; D002999:Clone Cells; D003596:Cytosine / Q000031:analogs & derivatives* / Q000378:metabolism; D004262:DNA Restriction Enzymes / Q000378:metabolism; D004279:DNA, Viral / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology / Q000821:virology; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D039002:Prophages / Q000235:genetics; D017422:Sequence Analysis, DNA; D013379:Substrate Specificity
D036022:Capsid Proteins; D004279:DNA, Viral; C035493:DNA, glucosylated; D029968:Escherichia coli Proteins; C046947:internal protein I, bacteriophage T4; C011865:5-hydroxymethylcytosine; D044503:5-Methylcytosine; D003596:Cytosine; D004262:DNA Restriction Enzymes