A translational enhancer derived from tobacco mosaic virus is functionally equivalent to a Shine-Dalgarno sequence

Area of Science:

• Molecular Biology
• Virology
• Bacteriology

Background:

• The 5' untranslated leader sequence (omega) of tobacco mosaic virus RNA enhances translation in both eukaryotic and prokaryotic systems.
• Understanding translational enhancement mechanisms is crucial for optimizing gene expression in diverse organisms.

Purpose of the Study:

• To evaluate the translational enhancement potential of a truncated omega sequence (omega delta 3).
• To assess the efficacy of omega delta 3 in Gram-negative bacteria, with or without a native ribosomal binding site (RBS).

Main Methods:

• Constructed gene expression vectors with omega delta 3 and reporter genes (chloramphenicol acetyltransferase and beta-glucuronidase).
• Tested constructs in various Gram-negative bacteria (Escherichia coli, Agrobacterium tumefaciens, Xanthomonas campestris pv. vitians, Erwinia amylovora, Salmonella typhimurium).
• Assessed protein production in vivo with and without the native RBS.

Main Results:

• Omega delta 3 enhanced protein production 40- to 120-fold in constructs lacking a native RBS.
• Similar enhancement levels (30- to 240-fold) were observed for beta-glucuronidase.
• Enhancement was significantly lower (1- to 3.8-fold) when a native RBS was present.
• The enhancing effect of omega delta 3 was independent of its position relative to the initiation codon.

Conclusions:

• The omega delta 3 sequence is a potent enhancer of bacterial translation, particularly in the absence of a native RBS.
• This truncated sequence offers a versatile tool for boosting gene expression in a wide range of Gram-negative bacteria.
• Omega delta 3's position-independent enhancement broadens its applicability in genetic engineering.