Magnesium Acetate Induces a Conformational Change in Escherichia coli Primase

Teresa M. Urlacher, Mark A. Griep

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


Primase from Escherichia coli is a single-stranded DNA-dependent RNA polymerase. As such, it requires magnesium to carry out catalysis. Limited tryptic digestion was used to probe the conformations of primase as a function of magnesium acetate concentration. In the absence of magnesium, trypsin cleaved primase at three sites. Magnesium acetate induced a conformational change such that one of these sites became inaccessible to trypsin digestion and a new site became trypsin accessible. The conformational change was only induced by Mg(OAc)2 and not MnCh, CaCL, NaOAc or LiCl, indicating a clear magnesium acetate-dependent conformational change. The effect was slightly induced by MgSO4 and MgCh. An allosteric binding model indicates that primase binds at least two magnesiums in a cooperative manner. The data were best fit to a two-state model in which one conformation had a high affinity for magnesium, KR = 83.4 M-1, and the other state had virtually no affinity.

Original languageEnglish (US)
Pages (from-to)16708-16714
Number of pages7
Issue number51
StatePublished - Dec 1995

ASJC Scopus subject areas

  • Biochemistry


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