Structure function relationships in the ribosomal stalk proteins of archaebacteria

Area of Science:

• Molecular Biology
• Biochemistry
• Structural Biology

Background:

• Ribosomal protein L12 is crucial for translation.
• Archaebacterial ribosomes have unique structural and functional properties.
• Understanding L12 protein function is key to deciphering archaeal translation.

Purpose of the Study:

• To investigate the functional domains of Sulfolobus solfataricus L12 protein (SsoL12).
• To determine the binding site and functional requirements of SsoL12 on the ribosome.
• To explore the exchangeability of archaebacterial L12 proteins.

Main Methods:

• Subcloning and overexpression of SsoL12 and its mutants in Escherichia coli.
• Purification of wild-type and mutant SsoL12 proteins.
• Selective removal of SsoL12 from S. solfataricus ribosomes and reconstitution experiments.
• In vitro translational activity assays and 2D-PAGE analysis.

Main Results:

• NH2-terminal truncation prevents SsoL12 binding to ribosomes, indicating the NH2-terminus is essential for ribosome interaction.
• COOH-terminal truncated SsoL12 mutants bind to ribosomes but do not restore translational activity.
• Reconstitution experiments demonstrate that archaebacterial L12 proteins are freely exchangeable on the ribosome.

Conclusions:

• The NH2-terminal region of SsoL12 is critical for ribosome binding.
• The COOH-terminal region is essential for SsoL12's translational function.
• Archaebacterial ribosomes can accommodate and utilize externally supplied L12 proteins, highlighting their dynamic nature.