A switch in translation mediated by an antisense RNA

Area of Science:

• Molecular Biology
• Bacteriophage Genetics
• RNA Regulation

Background:

• Antisense RNAs are known regulators of gene expression.
• Bacteriophage P22 has a gene, sieB, that can abort lytic development in other phages.
• P22 possesses a gene, esc, which confers resistance to SieB-mediated exclusion.

Purpose of the Study:

• To investigate the mechanism by which bacteriophage P22 evades SieB-mediated exclusion.
• To elucidate the role of antisense RNA in regulating the expression of the sieB gene.
• To understand how P22's Esc protein interacts with exclusion systems of other phages.

Main Methods:

• Analysis of gene expression in bacteriophage P22.
• Identification and characterization of antisense RNA (sas) and its target.
• Genetic manipulation of P22 to study the function of sieB and esc genes.
• Investigation of P22's interaction with bacteriophage lambda's exclusion system.

Main Results:

• The sieB gene encodes two polypeptides: SieB (exclusion protein) and Esc (a truncated inhibitor of SieB).
• Bacteriophage P22 synthesizes antisense RNA (sas) that selectively inhibits SieB synthesis while allowing Esc production.
• This translational switch is crucial for P22's vegetative development, preventing self-exclusion.
• P22's Esc protein can overcome the exclusion system of bacteriophage lambda.

Conclusions:

• Antisense RNA-mediated translational control is a key mechanism for bacteriophage P22 to regulate gene expression and ensure its survival.
• The selective inhibition of SieB synthesis by sas RNA allows P22 to bypass host or superinfecting phage exclusion systems.
• This study reveals a novel strategy of translational regulation for phage-host interaction and immune evasion.