RNase III-dependent hydrolysis of lambda cII-O gene mRNA mediated by lambda OOP antisense RNA.

Area of Science:

• Molecular Biology
• RNA Regulation
• Bacteriophage Genetics

Background:

• Bacteriophage lambda utilizes antisense RNA for gene regulation.
• The OOP antisense RNA (RNA) plays a role in regulating lambda's cII and O genes.
• Understanding the mechanism of OOP RNA-mediated gene silencing is crucial.

Purpose of the Study:

• To elucidate the mechanism by which bacteriophage lambda's OOP antisense RNA inhibits cII gene expression.
• To identify the specific cleavage sites and processing pathways of cII-O mRNA mediated by OOP RNA.
• To compare the roles of RNase III-dependent and -independent pathways in OOP RNA function.

Main Methods:

• Primer extension analysis of cellular RNA from lambda lysogens containing OOP DNA plasmids.
• Ribonuclease protection experiments to detect mRNA cleavage products.
• Comparative analysis of RNA processing in RNase III-positive and RNase III-negative cells.

Main Results:

• OOP RNA inhibits lambda cII gene expression approximately 100-fold.
• A specific cleavage site on cII-O mRNA was identified within the OOP RNA complementarity region.
• RNase III-dependent cleavage of cII-O mRNA occurs efficiently in RNase III+ cells, leading to degradation of cII-proximal fragments.
• An alternative RNase III-independent cleavage pathway exists in RNase III- cells, stabilizing cII-proximal fragments while degrading O-proximal fragments.

Conclusions:

• Bacteriophage lambda's OOP RNA employs distinct RNase III-dependent and -independent mechanisms to regulate cII-O mRNA processing and gene expression.
• The RNase III-dependent pathway is the primary mechanism for efficient inhibition of cII gene expression.
• The observed differences in fragment stability highlight the complex regulatory roles of RNA processing in bacteriophage lambda.