A highly conserved DNA replication module from Streptococcus thermophilus phages is similar in sequence and topology to a module from Lactococcus lactis phages.
Virology
; 234(2): 372-82, 1997 Aug 04.
Article
en En
| MEDLINE
| ID: mdl-9268169
A highly conserved DNA region extending over 5 kb was observed in Streptococcus thermophilus bacteriophages. Comparative sequencing of one temperate and 26 virulent phages demonstrated in the most extreme case an 18% aa difference for a predicted protein, while the majority of the phages showed fewer, if any aa changes. The relative degree of aa conservation was not homogeneous over the DNA segment investigated. Sequence analysis of the conserved segment revealed genes possibly involved in DNA transactions. Three predicted proteins (orf 233, 443, and 382 gene product (gp)) showed nucleoside triphosphate binding motifs. Orf 443 gp showed in addition a DEAH box motif, characteristically found in a subgroup of helicases, and a variant zinc finger motif known from a phage T7 helicase/primase. Tree analysis classified orf 443 gp as a distant member of the helicase superfamily. Orf 382 gp showed similarity to putative plasmid DNA primases. Downstream of orf 382 a noncoding repeat region was identified that showed similarity to a putative minus origin from a cryptic S. thermophilus plasmid. Four predicted proteins showed not only high degrees of aa identity (34 to 63%) with proteins from Lactococcus lactis phages, but their genes showed a similar topological organization. We interpret this as evidence for a horizontal gene transfer event between phages of the two bacterial genera in the distant past.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Streptococcus
/
Bacteriófagos
/
ADN Viral
/
Lactococcus lactis
/
Replicación del ADN
Tipo de estudio:
Prognostic_studies
Idioma:
En
Revista:
Virology
Año:
1997
Tipo del documento:
Article
País de afiliación:
Suiza
Pais de publicación:
Estados Unidos