DNA inversion in the tail fiber gene alters the host range specificity of carotovoricin Er, a phage-tail-like bacteriocin of phytopathogenic Erwinia carotovora subsp. carotovora Er.
Carotovoricin Er is a phage-tail-like bacteriocin produced by Erwinia carotovora subsp. carotovora strain Er, a causative agent for soft rot disease in plants. Here we studied binding and killing spectra of carotovoricin Er preparations for various strains of the bacterium (strains 645Ar, EC-2, N786, and P7) and found that the preparations contain two types of carotovoricin Er with different host specificities; carotovoricin Era possessing a tail fiber protein of 68 kDa killed strains 645Ar and EC-2, while carotovoricin Erb with a tail fiber protein of 76 kDa killed strains N786 and P7. The tail fiber proteins of 68 and 76 kDa had identical N-terminal amino acid sequences for at least 11 residues. A search of the carotovoricin Er region in the chromosome of strain Er indicated the occurrence of a DNA inversion system for the tail fiber protein consisting of (i) two 26-bp inverted repeats inside and downstream of the tail fiber gene that flank a 790-bp fragment and (ii) a putative DNA invertase gene with a 90-bp recombinational enhancer sequence. In fact, when a 1,400-bp region containing the 790-bp fragment was amplified by a PCR using the chromosomal DNA of strain Er as the template, both the forward and the reverse nucleotide sequences of the 790-bp fragment were detected. DNA inversion of the 790-bp fragment also occurred in Escherichia coli DH5alpha when two compatible plasmids carrying either the 790-bp fragment or the invertase gene were cotransformed into the bacterium. Furthermore, hybrid carotovoricin CGE possessing the tail fiber protein of 68 or 76 kDa exhibited a host range specificity corresponding to that of carotovoricin Era or Erb, respectively. Thus, a DNA inversion altered the C-terminal part of the tail fiber protein of carotovoricin Er, altering the host range specificity of the bacteriocin.
Nguyen
H A
HA
Department of Molecular and Cell Biology, Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumi-dori Amamiya-machi, Aoba-ku, Sendai 981-8555, Japan.
Tomita
T
T
Hirota
M
M
Kaneko
J
J
Hayashi
T
T
Kamio
Y
Y
D001430:Bacteriocins / Q000235:genetics* / Q000378:metabolism; D007446:Chromosome Inversion; D004269:DNA, Bacterial / Q000235:genetics; D005798:Genes, Bacterial; D006790:Host-Parasite Interactions; D008957:Models, Genetic; D016973:Pectobacterium carotovorum / Q000235:genetics* / Q000378:metabolism / Q000472:pathogenicity*; D013045:Species Specificity
D001430:Bacteriocins; D004269:DNA, Bacterial; C046776:carotovoricin