DOMAINS OF ESCHERICHIA-COLI PRIMASE - FUNCTIONAL-ACTIVITY OF A 47-KDAN-TERMINAL PROTEOLYTIC FRAGMENT

Endoproteinase Asp-N cleaves the 581-amino acid Escherichia coli prima se (65,564 Da) into several major fragments. One of these, a 47-kDa fr agment containing the complete N terminus and the first 422 amino acid s of primase, is capable of primer RNA (pRNA) synthesis in the G4ori(c )/single-stranded DNA binding protein/primase pRNA synthesis system. A cloned 398-amino acid N-terminal fragment of primase can also synthes ize pRNA. The sizes of the pRNA synthesized by these N terminal fragme nts, however, are smaller than those synthesized by intact primase, su ggesting that the C-terminal region of primase plays a role in process ivity or regulation of pRNA synthesis. Primase mutants with the last 1 0 and 40 C-terminal amino acids deleted synthesize pRNA as wild-type p rimase, indicating that any regulatory sequences must be internal to t he C terminus of primase.