Abstract

Legionella pneumophila, the cause of Legionnaires disease, is able to survive intracellularily in eukaryotic cells such as monocytes, macorphages, and protozoan ogranisms. During protein biosynthesis, the rph gene encodes ribonuclease (RNase) PH which functions as a phosphorolytic nuclease that removes nucleotides following the CCA terminus of tRNA and as a nucleotidyl-transferase which adds nucleotides to the ends of RNA molecules by usingnucelside diohosphates as substrates.In this sutdy, the rph gene was screened in pUC19 library employing a DNA probe whcich was constructed from PCR based on a consensus pattern of multiple alignment of RNas PH. The encoded protein consists of 235 amino acid residues with a calculated molecualr weight of 26,112 Daltons. The RNase PH signature domains are completely conserved.

• Keywords: Exo-ribonuclease; Legionella pneumophila; RNase PH; rph gene