TY - JOUR
T1 - Bacteriophage lambda derivatives carrying two copies of the cohesive end site
AU - Emmons, Scott W.
N1 - Funding Information:
I would like to thank Dr R. L. Baldwin for the guidance he has provided throughout the course of the work presented bore, and Dr M. Feias for stimulating communications regarding our complementary results, as well as for the gift of several strains. I am grateful for discussions with Drs R. Hendrix, M. Syvanon, J. Thomas and R. White. Their suggestions regarding the work and the manuscript were invaluable. I am also grateful to Drs A. D. Kaiser and A. Campbell for their comments on the manuscript. This research was supported by National Institutes of Health grant GAfAMI9, 988-13, National Science Foundation grant GB-35432X, both grants to Dr R. L. Baldwin. author a U.S. Public Health Service Predoctoral Trainee.
PY - 1974/3/15
Y1 - 1974/3/15
N2 - A spontaneously arising tandem duplication derivative of bacteriophage lambda has been isolated, which carries two copies of the site where the cohesive ends are formed (designated cos). Its structure has been determined by electron microscopy of DNA heteroduplexes. These heteroduplexes reveal that the duplication is usually, but not always, carried on the left end of the chromosome. A second duplication phage having two copies of cos, constructed by Feiss & Campbell (1974), has also been studied by electron microscopy and is found to have a similar property. Unlike most tandem duplication derivatives of phage λ, the mutant studied here is not stable during growth in the absence of generalized recombination, but segregates both the triplication and the parental phage. This verifies that both cos sites are functional. The triplication does not arise as a result of end-to-end aggregation of phage chromosomes or site-specific recombination catalyzed by the chromosome maturation system at cos. It must therefore result from the cutting of mature ι chromosomes from concatemeric replication intermediates. The pattern of cutting observed shows that the λ cohesive ends are not created by a free nuclease acting on unpackaged DNA. The cutting appears to be influenced by the amount of DNA previously packaged into a phage head. A model for λ packaging is presented which explains the results. The duplication phage of Feiss & Campbell (1974) carries a novel addition containing self-complementary sequences.
AB - A spontaneously arising tandem duplication derivative of bacteriophage lambda has been isolated, which carries two copies of the site where the cohesive ends are formed (designated cos). Its structure has been determined by electron microscopy of DNA heteroduplexes. These heteroduplexes reveal that the duplication is usually, but not always, carried on the left end of the chromosome. A second duplication phage having two copies of cos, constructed by Feiss & Campbell (1974), has also been studied by electron microscopy and is found to have a similar property. Unlike most tandem duplication derivatives of phage λ, the mutant studied here is not stable during growth in the absence of generalized recombination, but segregates both the triplication and the parental phage. This verifies that both cos sites are functional. The triplication does not arise as a result of end-to-end aggregation of phage chromosomes or site-specific recombination catalyzed by the chromosome maturation system at cos. It must therefore result from the cutting of mature ι chromosomes from concatemeric replication intermediates. The pattern of cutting observed shows that the λ cohesive ends are not created by a free nuclease acting on unpackaged DNA. The cutting appears to be influenced by the amount of DNA previously packaged into a phage head. A model for λ packaging is presented which explains the results. The duplication phage of Feiss & Campbell (1974) carries a novel addition containing self-complementary sequences.
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U2 - 10.1016/0022-2836(74)90511-7
DO - 10.1016/0022-2836(74)90511-7
M3 - Article
C2 - 4598361
AN - SCOPUS:0015976703
SN - 0022-2836
VL - 83
SP - 511
EP - 525
JO - Journal of Molecular Biology
JF - Journal of Molecular Biology
IS - 4
ER -