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Appl. Environ. Microbiol., 04 1995, 1371-1377, Vol 61, No. 4
GE Allison, RW Worobo, ME Stiles and TR Klaenhammer
The lactacin F complex, composed of LafA and LafX peptides, is produced by
Lactobacillus johnsonii VPI 11088 and is active against five other
Lactobacillus species and Enterococcus faecalis. The genetic determinants
encoding the lactacin F complex are organized in a 1-kb polycistronic
operon which comprises three genes, lafA, lafX, and ORFZ (encoding the
putative immunity protein). The lafA and lafX genes encode the bacteriocin
precursors with N-terminal extensions characterized by a Gly-Gly-1*Xaa+1
cleavage site (*). The Gly-Gly motif is conserved in several other
bacteriocins, including carnobacteriocins A, BM1, and B2. Carnobacterium
piscicola LV17 produces carnobacteriocins which are active against Listeria
monocytogenes and other lactic acid bacteria. In this study, the lactacin F
operon was introduced into C. piscicola LV17. The transformants produced
lactacin F concurrently with the carnobacteriocins. When the lafA and lafX
genes were separated and cloned individually into LV17, production of
either LafA or LafX by C. piscicola LV17 was detected by complementation
with L. johnsonii clones producing LafX or LafA, respectively.
Transformants of C. piscicola LV17 which produced lactacin F, LafA, or
LafX, in combination with the carnobacteriocins, were assayed for an
increased and expanded inhibitory spectrum. The recombinant organisms were
only active against lactacin F- and carnobacteriocin-sensitive strains. A
plasmidless derivative of LV17 which does not produce the carnobacteriocins
failed to produce lactacin F, LafA, or LafX when transformed with the
appropriate recombinant plasmids. The ability of C. piscicola LV17 to
produce lactacin F demonstrates that the machinery for the
carnobacteriocins is capable of processing and exporting bacteriocins from
both systems.
Copyright © 1995, American Society for Microbiology
Heterologous expression of the lactacin F peptides by Carnobacterium piscicola LV17
Department of Microbiology, North Carolina State University, Raleigh 27695-7624, USA.
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