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Ribosome-inhibiting proteins, retroviral reverse transcriptases, and RNase H share common structural elements
M P Ready1, B J Katzin, J D Robertus
1Clayton Foundation Biochemical Institute, Department of Chemistry, University of Texas, Austin 78712.
Proteins
|January 1, 1988
Summary
Plant ribosome-inhibiting proteins share structural similarities with bacterial RNase H and viral reverse transcriptase enzymes. These findings suggest an ancient protein-folding unit involved in nucleic acid binding and modification.
Area of Science:
- Molecular Biology
- Biochemistry
- Structural Biology
Background:
- Plant ribosome-inhibiting proteins (RIPs) are a class of proteins with diverse biological activities.
- Homology studies are crucial for understanding protein function and evolutionary relationships.
Purpose of the Study:
- To investigate the structural and functional homology of plant ribosome-inhibiting proteins.
- To explore evolutionary links between RIPs, bacterial RNase H, and viral reverse transcriptases.
Main Methods:
- Domain-level homology analysis comparing RIPs with known enzymes.
- Structural analysis of conserved residues within the tertiary structure of ricin.
Main Results:
- Plant ribosome-inhibiting proteins exhibit domain-level homology to Escherichia coli RNase H.
- Homology was also found with two regions of the pol gene product of retroviral reverse transcriptases, including integrase and RNase H activities.
- Conserved residues in a structural cleft of ricin suggest roles in binding or catalysis.
Conclusions:
- The conserved sequences likely represent ancient protein-folding units involved in nucleic acid binding and modification.
- These ancient units have been adapted into various enzymatic functions across different organisms.