Nucleic Acid Polymerases: Possible Subunit Structure.

A hybrid polymerase which catalyzes the synthesis only of helical polynucleotides with one DNA-like strand and one RNA-like strand can be altered by certain treatments so that it will then synthesize DNA and RNA. There is evidence that the alteration involves a separation or rearrangement of polymerase subunits of several kinds. Two types of RNA polymerase activity have been found: one produces single chains, and the other, two complementary chains simultaneously. The latter type of RNA polymerase, the hybrid polymerase, and the DNA polymerase behave as though they were bifunctional, and each may be composed of two monofunctional subunits.