RNA Primer Synthesis

RNA Primer Synthesis

RNA Primer Synthesis - DNA synthesis takes place by an ordered polymerization of deoxyribonucleotides. This can take place only on the 3'-OH terminus of apolynucleotide primer. Thus an RNA primer is essential for DNA chain synthesis. There are three enzymatic pathways for primer synthesis in circular ssDNA phages.

(i) In the phages fd and M13, catalysis of RNA priming is by RNA polymerase,

(ii) In the phages 04 and ST-l RNA priming is catalysed by the dnaG protein. This protein is a monomer of about 60,000 daltons, and catalyses the formation of the four ribose nucleoside triphosphates (rNTPs) into an oligonucleotide primer.

(iii) In ØXI74 catalysis of RNA priming is by the dnaG protein after prepriming with dnaB and dnaC proteins. RNA priming is resistant to rifampicin inhibition, showing that it is not dependent on RNA polymerase.

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