Structural insights into cell cycle control by essential GTPase Era.

Area of Science:

• Molecular Biology
• Bacteriology
• Genetics

Background:

• Escherichia coli Ras-like protein (Era) is crucial for bacterial cell viability.
• Era comprises an N-terminal GTPase domain and a C-terminal KH domain.
• It plays a key role in 16S ribosomal RNA (rRNA) processing and 30S ribosomal subunit maturation.

Purpose of the Study:

• To elucidate the mechanism by which Era regulates 30S ribosomal subunit maturation.
• To investigate the interaction between Era, 16S rRNA, and GTP.
• To explore the implications of Era's function for eukaryotic cell cycle control.

Main Methods:

• The study focused on the molecular interactions and functional roles of Era in bacterial systems.
• Specific nucleotide sequences (1530GAUCACCUCC1539) and helix 45 (h45) of 16S rRNA were identified as key binding sites for Era.
• The study examined the GTP-binding and GTP-hydrolyzing activities of Era in relation to RNA binding.

Main Results:

• Era binds to a specific 10-nucleotide sequence near the 3' end of 16S rRNA and interacts with helix 45.
• GTP binding is essential for Era's RNA interaction, and RNA binding stimulates Era's GTPase activity.
• GTP hydrolysis leads to Era's release from the mature 30S ribosomal subunit, thereby controlling cell growth rate.

Conclusions:

• Bacterial Era acts as a molecular switch, controlling cell growth by regulating 30S ribosomal subunit maturation through a GTP-dependent mechanism.
• The conserved nature of the GAUCA sequence and h45 across all three kingdoms of life suggests a fundamental biological role.
• Understanding bacterial Era function provides valuable insights into the regulation of cell cycle control in eukaryotic organisms.