TY - JOUR
T1 - A "retrocidal" plasmid in Enterococcus faecalis
T2 - Passage and protection
AU - Flannagan, Susan E.
AU - Clewell, Don B.
AU - Sedgley, Christine M.
N1 - Funding Information:
This work was supported by The University of Michigan School of Dentistry.
PY - 2008/5
Y1 - 2008/5
N2 - Enterococcus faecalis MC4 harbors a 130 kb conjugative, pheromone (cCF10)-responding plasmid, pAMS1, conferring chloramphenicol, streptomycin and tetracycline resistances. A plasmid-borne class IIa bacteriocin (MC4-1) determinant and cognate immunity gene were present, but not expressed in MC4. However, pAMS1 transfer to E. faecalis JH2-2 (but not to the non-isogenic OG1SS) generated the surprising ability to express bacteriocin activity against the plasmid donor, MC4. The bacteriocin target spectrum includes E. faecalis, Enterococcus faecium, Enterococcus gallinarum, Enterococcus hirae, and Listeria monocytogenes. Those donors unable to express bacteriocin or immunity could protect themselves from the "retrocidal" behavior of transconjugants by a switch to bacteriocin resistance at a frequency of ∼10-3. Reversion to sensitivity occurred at a relatively high frequency, suggestive of involvement of a phase variation event. These observations concerning a conjugative plasmid with novel "retrocidal" properties, coupled with a defense mechanism independent of plasmid-borne immunity functions, may relate to phenomena exploiting regulatory features with broader ecological and evolutionary implications.
AB - Enterococcus faecalis MC4 harbors a 130 kb conjugative, pheromone (cCF10)-responding plasmid, pAMS1, conferring chloramphenicol, streptomycin and tetracycline resistances. A plasmid-borne class IIa bacteriocin (MC4-1) determinant and cognate immunity gene were present, but not expressed in MC4. However, pAMS1 transfer to E. faecalis JH2-2 (but not to the non-isogenic OG1SS) generated the surprising ability to express bacteriocin activity against the plasmid donor, MC4. The bacteriocin target spectrum includes E. faecalis, Enterococcus faecium, Enterococcus gallinarum, Enterococcus hirae, and Listeria monocytogenes. Those donors unable to express bacteriocin or immunity could protect themselves from the "retrocidal" behavior of transconjugants by a switch to bacteriocin resistance at a frequency of ∼10-3. Reversion to sensitivity occurred at a relatively high frequency, suggestive of involvement of a phase variation event. These observations concerning a conjugative plasmid with novel "retrocidal" properties, coupled with a defense mechanism independent of plasmid-borne immunity functions, may relate to phenomena exploiting regulatory features with broader ecological and evolutionary implications.
KW - Bacteriocin MC4-1
KW - Conjugation
KW - Enterococcus faecalis
KW - Resistance
KW - Sex pheromone
KW - pAMS1
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U2 - 10.1016/j.plasmid.2008.01.002
DO - 10.1016/j.plasmid.2008.01.002
M3 - Article
C2 - 18295881
AN - SCOPUS:41549134454
SN - 0147-619X
VL - 59
SP - 217
EP - 230
JO - Plasmid
JF - Plasmid
IS - 3
ER -