Recombinant Escherichia coli O127:H6 GTPase Era (era)
Description
Molecular Definition and Significance
Recombinant Era refers to genetically modified versions of the native E. coli Era protein, often fused with tags like glutathione S-transferase (GST) or polyhistidine (His) to facilitate purification and functional studies . Era is a member of the TRAFAC class of GTPases, characterized by:
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KH domain: Binds RNA, particularly the 3′-end of 16S rRNA (residues 171–296)
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Membrane association: Loosely linked to the inner membrane in E. coli
Era’s essentiality stems from its role in ribosome biogenesis, where it stabilizes immature 16S rRNA and facilitates small ribosomal subunit (SSU) assembly .
Biochemical Properties
Recombinant Era variants exhibit distinct biochemical behaviors depending on purification methods and fusion partners:
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GTP hydrolysis: Requires K⁺ ions for optimal activity (10× stimulation) .
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RNA dependency: GTPase activity drops by 80% when RNA is removed .
Functional Roles in Ribosome Assembly
Era interacts with multiple ribosomal components and assembly factors:
The era(T99I) mutation improves 16S rRNA processing at 37°C but fails to suppress ΔybeY temperature sensitivity .
Mutational Analysis
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G1/G4 motif mutations (e.g., K21R, N236I): Lethal in E. coli; linked to Perrault syndrome in humans .
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KH domain overexpression: Toxic due to uncontrolled rRNA binding .
Ribosome Binding Dynamics
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Apo-Era: Binds 16S rRNA and SSU with high affinity; GTP/GDP reduce binding .
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Mitochondrial ERAL1: Captured in nucleotide-free state on nascent SSU, suggesting GTP loading occurs post-recruitment .
Genetic Interactions
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ΔrbfA suppression: Requires intact Era linker region; 8-residue extensions abolish rescue .
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YbeY-Era fusion: Observed in Clostridia, highlighting evolutionary coadaptation .
Open Questions and Challenges
Product Specs
Target Background
KEGG: ecg:E2348C_2843
