The RNA-binding domain of ribosomal protein L11 recognizes an rRNA tertiary structure stabilized by both thiostrepton and magnesium ion

Area of Science:

• Molecular Biology
• Structural Biology
• Biochemistry

Background:

• Antibiotics inhibiting ribosomal function can disrupt protein synthesis via various mechanisms.
• Thiostrepton is known to bind the GTPase center of the large ribosomal subunit.
• Previous hypotheses suggested thiostrepton prevents conformational changes in ribosomal protein L11 or 23S ribosomal RNA (rRNA).

Purpose of the Study:

• To investigate the role of magnesium ions (Mg2+), protein L11, and thiostrepton in the folding of a 23S rRNA fragment.
• To elucidate the mechanism by which thiostrepton influences rRNA structure and L11 binding.

Main Methods:

• Utilized scintillation proximity assays to study the binding of the L11 C-terminal RNA-binding domain to a 23S rRNA fragment.
• Assessed thiostrepton's ability to induce L11-rRNA binding.
• Employed both Escherichia coli and a thermostable rRNA variant for comparative analysis.

Main Results:

• Demonstrated that Mg2+, L11, and thiostrepton are crucial for the formation and maintenance of the rRNA fragment's tertiary structure.
• Showed that Mg2+, L11, and thiostrepton collectively induce the rRNA to fold into an essentially identical tertiary structure.
• Confirmed the cooperative roles of these components in achieving a specific, stable rRNA conformation.

Conclusions:

• Thiostrepton, in conjunction with Mg2+ and L11, plays a critical role in inducing and stabilizing a specific tertiary structure of the 23S rRNA.
• The findings support the mechanism where thiostrepton binding facilitates essential conformational changes in the ribosome, impacting its function.