FIG. 2.

Synthesis of pRNA by wild-type primase and mutant proteins in the presence of Mg²⁺ ions. (A) pRNA synthesized by wild-type (wt) and mutant primase proteins. In this study, the major products were about 22 to 25 nucleotides long. The position of free [α-³²P]GTP not incorporated into the pRNA product is indicated by the arrowhead labeled GTP. Primase protein was absent in the control reaction mixture (lane 8). (B) pRNA synthesized by K229A and M268A mutant proteins compared with the product synthesized by the K241R mutant protein, the previously described primase mutant which was demonstrated to synthesize only 2-nucleotide RNA (22). (C) pRNA synthesized by the Y267A mutant protein compared with the product synthesized by the previously described K241R mutant protein (22).