Infect Immun, June 1998, p. 2743-2749, Vol. 66, No. 6
0019-9567/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.

and
Department of Oral Biology,
Received 24 November 1997/Returned for modification 18 December
1997/Accepted 4 March 1998
Streptococcus mutans JH1000 and its derivatives were
previously shown (J. D. Hillman, K. P. Johnson, and B. I. Yaphe, Infect. Immun. 44:141-144, 1984) to produce a
low-molecular-weight, broad-spectrum bacteriocin-like inhibitory
substance (BLIS). The thermosensitive vector pTV1-OK harboring
Tn917 was used to isolate a BLIS-deficient mutant, DM25,
and the mutated gene was recovered by shotgun cloning in
Escherichia coli. Sequence analysis of insert DNA adjacent to Tn917 led to the identification of four open reading
frames including two (lanA and lanB) which have
substantial homology to the Staphylococcus epidermidis
structural gene (epiA) and a modifying enzyme gene
(epiB) for biosynthesis of the lantibiotic epidermin,
respectively. Although the BLIS activity could not be recovered from
broth cultures, high yields were obtained from a solid medium
consisting of Todd-Hewitt broth containing 0.5% agarose that was stab
inoculated with JH1140 (a spontaneous mutant of JH1000 that produces
threefold-elevated amounts of activity). Agar could not substitute for
agarose. Chloroform extraction of the spent medium produced a fraction
which yielded two major bands on sodium dodecyl sulfate-polyacrylamide
gel electrophoresis. The faster-migrating band was absent in chloroform
extracts of the mutant, DM25. The amino acid sequence of this band was
determined by Edman sequencing and mass spectroscopy. The results
showed that it is a lantibiotic, which we have named mutacin 1140, and that the sequence corresponded to that deduced from the
lanA sequence. We observed a number of similarities of
mutacin 1140 to epidermin and an S. mutans lantibiotic,
B-Ny266, but it appears to have significant differences in the
positions of its thioether bridges. It also has other unique features
with regard to its leader sequence and posttranslational modification.
A proposed structure for mutacin 1140 is presented.
*
Corresponding author. Mailing address: University
of Florida School of Dentistry, Box 100424, Gainesville, FL
32610. Phone: (352) 846-0792. Fax: (352) 392-2361. E-mail:
jhillman{at}dental.ufl.edu.
Present address: Millennium Pharmaceuticals, Inc., Cambridge,
MA 02189.
Present address: University of Toronto Dental Research Institute,
Toronto, Canada M5G 1G6.
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