A new form of DNA polymerase 3 and a copolymerase replicate a long, single-stranded primer-template.
A new form of DNA polymerase III, termed Pol III star (Pol III(*)), has been purified to homogeneity from Escherichia coli. Pol III(*) is temperature sensitive when isolated from a thermo-sensitive dnaE mutant, as had been described for Pol III. Pol III(*) and Pol III are separable by gel filtration. Pol III(*) utilizes a duplex template containing short gaps with the same catalytic properties as Pol III. However, Pol III(*) is able to replicate long, singlestranded templates such as homopolymer chains and viral circles of M13 and varphiX174 if provided with the following: spermidine, a primer fragment, and a new protein, termed copolymerase III(*) (Copol III(*)). The latter, purified to homogeneity, has no known independent enzymatic activity and supports synthesis by Pol III(*) but not by Pol I, Pol II, or Pol III.
D002499:Centrifugation, Density Gradient; D011232:Chemical Precipitation; D002845:Chromatography; D002848:Chromatography, DEAE-Cellulose; D002850:Chromatography, Gel; D003067:Coenzymes / Q000302:isolation & purification / Q000378:metabolism*; D003090:Coliphages / Q000378:metabolism; D004254:DNA Nucleotidyltransferases / Q000302:isolation & purification / Q000378:metabolism*; D004261:DNA Replication; D004277:DNA, Single-Stranded / Q000096:biosynthesis; D004279:DNA, Viral / Q000096:biosynthesis*; D004589:Electrophoresis, Disc; D004926:Escherichia coli / Q000201:enzymology*; D013095:Spermidine; D013698:Templates, Genetic
D003067:Coenzymes; D004277:DNA, Single-Stranded; D004279:DNA, Viral; D004254:DNA Nucleotidyltransferases; D013095:Spermidine