Frameshifting Stimulatory Sequence Induces Large Structural Change of Ribosomal Proteins When Bound to E. coli...

Area of Science:

• Structural biology
• Molecular biology
• Biophysics

Background:

• Biological macromolecular machines, like ribosomes, exist in various conformations essential for cellular functions.
• Cryo-electron microscopy has advanced conformational analysis, but characterizing highly flexible regions remains challenging.
• Flexible ribosomal proteins interacting with mRNA stem-loop structures, such as frameshifting stimulatory sequences (FSS), are difficult to structurally resolve.

Purpose of the Study:

• To investigate the structural dynamics of ribosomes interacting with mRNA stem-loop structures.
• To compare the conformational changes of ribosomes bound to FSS stem-loops versus linear mRNA.
• To understand the implications of ribosomal protein flexibility in cellular mechanisms.

Main Methods:

• Utilized small-angle neutron/X-ray scattering (SANS/SAXS) and electron microscopy (EM).
• Studied ribosomal samples in complex with either an FSS stem-loop or linear mRNA.
• Compared structural differences between these two ribosome-mRNA states.

Main Results:

• A significant elongation of a large ribosomal protein stalk (22%) was observed when the 70S ribosome interacted with an mRNA stem-loop.
• This structural change highlights the extensive flexibility of ribosomal proteins.
• The findings provide insights into ribosome dynamics during mRNA interaction.

Conclusions:

• Ribosomal proteins possess considerable flexibility, which can be modulated by mRNA structures.
• This flexibility likely plays a role in important ribosomal functions, including those involving FSS.
• The study enhances understanding of ribosome conformational plasticity and its functional relevance.