The effect of plasmid copy number mutations on pT181 replication initiator protein expression.
Previous studies have shown that plasmid pT181 controls its replication by countertranscript-mediated regulation of the rate of synthesis of the pT181 initiator, RepC. In this study, the relation has been studied between plasmid copy number and RepC synthesis for a series of pT181 copy number mutants. For each mutant plasmid, the repC coding sequence along with its 5' regulatory region was translationally fused to the beta-lactamase structural gene on a vector plasmid unrelated to pT181. By means of these constructs, the effect of regulatory mutations on the initiator synthesis could be measured at constant copy number. With one exception, the mutant control regions showed elevated beta-lactamase activity in comparison to the wild-type. However, the relative increase was not very well correlated with the copy number of the corresponding mutant plasmid. The possibility is considered that factors such as DNA secondary structure may have important ancillary effects on the regulation mechanism.
Wang
P Z
PZ
Department of Plasmid Biology, Public Health Research Institute, City of New York, Inc., New York 10016.
Henriquez
V B
VB
Projan
S J
SJ
Iordanescu
S
S
Novick
R P
RP
D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D002872:Chromosome Deletion; D004265:DNA Helicases; D004261:DNA Replication; D004268:DNA-Binding Proteins; D004926:Escherichia coli / Q000235:genetics*; D016680:Genome, Bacterial; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009838:Oligodeoxyribonucleotides; D010957:Plasmids; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D015183:Restriction Mapping; D013211:Staphylococcus aureus / Q000235:genetics*; D015534:Trans-Activators; D014161:Transduction, Genetic; D014169:Transformation, Bacterial; D001616:beta-Galactosidase / Q000235:genetics / Q000378:metabolism; D001618:beta-Lactamases / Q000235:genetics / Q000378:metabolism
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D009838:Oligodeoxyribonucleotides; D011993:Recombinant Fusion Proteins; C043650:RepC protein, Staphylococcus aureus; D015534:Trans-Activators; C045264:replication initiator protein; D001616:beta-Galactosidase; D001618:beta-Lactamases; D004265:DNA Helicases