Ribosome collisions alter frameshifting at translational reprogramming motifs in bacterial mRNAs

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• Translational frameshifting is a mechanism where ribosomes shift reading frames on messenger RNAs (mRNAs).
• Existing models typically focus on single ribosomes interacting with mRNA motifs.
• Ribosomal protein bL9 is known to be important for reading frame maintenance and elongation factor P (EFP) function.

Purpose of the Study:

• To investigate the influence of ribosome abundance on frameshifting efficiency.
• To elucidate the role of ribosome collisions in frameshifting.
• To understand the function of ribosomal protein bL9 in frameshifting and ribosome dynamics.

Main Methods:

• Analysis of frameshifting levels on mRNAs containing IS3, dnaX, and prfB motifs under varying ribosome densities.
• Investigation of ribosome collisions during translational stalling using bacterial systems.
• Comparative studies of wild-type and bL9-deficient bacterial ribosomes.

Main Results:

• Ribosome abundance significantly impacts frameshifting efficiency, with collisions playing a key role.
• Ribosomes lacking bL9 exhibit increased compaction during collisions, potentially blocking E-sites and impairing transpeptidation.
• bL9 appears to suppress frameshifting by regulating E-site dynamics in stalled ribosomes.

Conclusions:

• Ribosome collisions, not just individual ribosome behavior, are critical for frameshifting regulation.
• bL9 is important for maintaining proper ribosome spacing and function during translation, particularly under stalling conditions.
• Naturally occurring frameshift elements may be fine-tuned by the relative abundance of ribosomes to mRNA.