Vol.30 No.3 (2008 June): 287-290

Prokaryotic Adaptive Immunity Mediated by RNA Interference System

Tie-Min Li*

(College of Life Science, Liaoning University, Shenyang 110036, China)

Abstract RNA interference (RNAi) system exists in a wide range of eukaryote and its mechanism has been understood well. Although it has been found that gene silencing which is mediated by prokaryotic micro RNA (miRNA) regulates bacteria gene expression, the gene silencing mechanism mediated by small interference RNA (siRNA) has not been proposed in prokaryote. Recent years, clustered regularly interspaced short palindromic repeat (CRISPR) and CRISPR-associated (cas) gene are increasingly discovered in prokaryotic genomes. The analysis and prediction by in silico indicated that CASS, which is composed of CRISPR and cas, triggered prokaryotic RNAi. A hypothesis was put forward proposing roles of CRISPR and cas, functioning on immune defense. More recently, experimental evidence supported the hypothesis. Meanwhile, the mechanism of prokaryotic adaptive immunity is revealed firstly. Prokaryotic RNAi system confers host immune defense with heritage by contrast to eukaryotic adaptive immunity in addition to specificity. This paper reviewed a variety of components associated with prokaryotic RNAi system and the mechanism of prokaryotic adaptive immunity via RNAi system.

Key words CRISPR; Cas protein; RNA interference; prokaryote; adaptive immunity

Received: October 11, 2007 Accepted: March 7, 2008
This work was supported by the Program for Science and Technology Innovation of Liaoning Province (No.2004205004)
*Corresponding author: Tel: 86-24-62202232, Fax: 86-24-62202796, E-mail: tieminli@lnu.edu.cn