TY - JOUR
T1 - Navel type I restriction specificities through domain shuffling of HsdS subunits in Lactococcus lactis
AU - O'sullivan, David
AU - Twomey, Denis P.
AU - Coffey, Aidan
AU - Hill, Colin
AU - Fitzgerald, Gerald F.
AU - Ross, R. Paul
N1 - Copyright:
Copyright 2017 Elsevier B.V., All rights reserved.
PY - 2000
Y1 - 2000
N2 - This study identifies a natural system in Lactococcus lactis, in which a restriction modification specificity subunit resident on a 6159 bp plasmid (pAH33) alters the specificity of a functional R/M mechanism encoded by a 20.3 kb plasmid, pAH82. The new specificity was identified after phenotypic and molecular analysis of a 26.5 kb co-integrate plasmid (pAH90), which was detected after bacteriophage challenge of the parent strain. Analysts of the regions involved in the co-integration revealed that two novel hybrid hsdS genes had been formed during the cointegration event. The HsdS chimeras had interchanged the C- and N-terminal variable domains of the parent subunits, generating two new restriction specificities. Comparison of the parent hsdS genes with other type I specificity determinants revealed that the region of the hsdS genes responsible for the co-integration event is highly conserved among lactococcal type I hsdS determinants. Thus, as hsdS determinants are widespread in the genus Lactococcus, new restriction specificities may evolve rapidly after homologous recombination between these genes. This study demonstrates that, similar to previous observations in Gram-negative bacteria, a Gram-positive bacterium can acquire novel restriction specificities naturally through domain shuffling of resident HsdS subunits.
AB - This study identifies a natural system in Lactococcus lactis, in which a restriction modification specificity subunit resident on a 6159 bp plasmid (pAH33) alters the specificity of a functional R/M mechanism encoded by a 20.3 kb plasmid, pAH82. The new specificity was identified after phenotypic and molecular analysis of a 26.5 kb co-integrate plasmid (pAH90), which was detected after bacteriophage challenge of the parent strain. Analysts of the regions involved in the co-integration revealed that two novel hybrid hsdS genes had been formed during the cointegration event. The HsdS chimeras had interchanged the C- and N-terminal variable domains of the parent subunits, generating two new restriction specificities. Comparison of the parent hsdS genes with other type I specificity determinants revealed that the region of the hsdS genes responsible for the co-integration event is highly conserved among lactococcal type I hsdS determinants. Thus, as hsdS determinants are widespread in the genus Lactococcus, new restriction specificities may evolve rapidly after homologous recombination between these genes. This study demonstrates that, similar to previous observations in Gram-negative bacteria, a Gram-positive bacterium can acquire novel restriction specificities naturally through domain shuffling of resident HsdS subunits.
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U2 - 10.1046/j.1365-2958.2000.01901.x
DO - 10.1046/j.1365-2958.2000.01901.x
M3 - Article
C2 - 10844674
AN - SCOPUS:0033625345
SN - 0950-382X
VL - 36
SP - 866
EP - 875
JO - Molecular Microbiology
JF - Molecular Microbiology
IS - 4
ER -