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Appl Environ Microbiol, March 1998, p. 1147-1152, Vol. 64, No. 3
Department of Food Science, Southeast Dairy
Foods Research Center, North Carolina State University, Raleigh,
North Carolina 27695-7624
Received 15 September 1997/Accepted 29 December 1997
A phage-inducible middle promoter (P15A10) from the
lytic, lactococcal bacteriophage
0099-2240/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
Common Elements Regulating Gene Expression in
Temperate and Lytic Bacteriophages of Lactococcus
Species
31, a member of the P335 species,
is located in an 888-base pair fragment near the right cohesive end. Sequence analysis revealed extensive homology (>95%) to the right cohesive ends of two temperate phages of the P335 species,
r1t and
LC3. Sequencing upstream and downstream of P15A10 showed that the high degree of homology between
31 and
r1t continued beyond the phage promoter. With the exception of one extra open reading
frame in
31, the sequences were highly homologous (95 to 98%)
between nucleotides 13448 and 16320 of the published
r1t sequence.
By use of a
-galactosidase (
-Gal) gene under the control of a
smaller, more tightly regulated region within the P15A10 promoter, P566-888, it was established that mitomycin C induction of a lactococcal strain harboring the prophage
r1t induced
the P566-888 promoter, as determined from an increase in
-Gal activity. Hybridization of nine other lactococcal strains with
32P-labeled P566-888 showed that the
Lactococcus lactis strains C10, ML8, and NCK203 harbored
sequences homologous to that of the phage-inducible promoter. Mitomycin
C induced the resident prophages in all these strains and concurrently
induced the P566-888 promoter, as determined from an
increase in
-Gal activity. DNA restriction analysis revealed that
the prophages in C10, ML8, and NCK203 had identical restriction
patterns which were different from that of
r1t. In addition, DNA
sequencing showed that the promoter elements in the three phages were
identical to each other and to P566-888 from the lytic
phage
31. These results point to a conserved mechanism in the
regulation of gene expression between the lytic phage
31 and at
least two temperate bacteriophages and provide further evidence for a
link in the evolution of certain temperate phages and lytic phages.
*
Corresponding author. Mailing address: Department of
Food Science, Southeast Dairy Foods Research Center, Box 7624, North Carolina State University, Raleigh, NC 27695-7624. Phone: (919) 515-2971. Fax: (919) 515-7124. E-mail: Klaenhammer{at}ncsu.edu.
Paper no. FSR 97-34 of the Department of Food Science, North
Carolina State University, Raleigh.
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