Recombinant Saguinus oedipus Non-secretory ribonuclease (RNASE2)
Description
Definition and Context
Recombinant Saguinus oedipus RNASE2 is a laboratory-engineered version of the ribonuclease 2 protein derived from the cotton-top tamarin (Saguinus oedipus), a New World (NW) monkey. Unlike secretory ribonucleases, this non-secretory form likely retains intracellular RNA-processing roles while exhibiting distinct catalytic properties compared to homologs in Old World (OW) monkeys and hominoids .
Catalytic Activity
Recombinant NW monkey RNASE2 exhibits reduced ribonucleolytic activity compared to OW/hominoid counterparts due to divergent residues:
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Arg64→Ser and Thr132→Arg substitutions in hominoids enhance RNA hydrolysis by optimizing substrate binding and transition-state stabilization .
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In NW monkeys, ancestral residues (Arg64, Thr132) result in weaker enzymatic activity. For example, owl monkey RNASE2 shows a 12-fold reduction in tRNA digestion compared to human EDN .
Experimental Data:
| RNASE2 Variant | Relative RNase Activity (%) | Source |
|---|---|---|
| Human EDN | 100 | |
| Owl monkey EDN | 8.3 | |
| Saguinus oedipus (inferred) | ~5–10 |
Antiviral Activity
Human RNASE2 (EDN) inhibits respiratory syncytial virus (RSV) via RNA degradation, but this activity is absent in NW monkey orthologs :
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Mechanism: Catalytic RNA cleavage disrupts viral replication .
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NW Monkey Limitation: Substitutions (e.g., Arg64) reduce both RNase and antiviral functions .
Antiviral Efficacy:
Evolutionary Insights
RNASE2 genes are under positive selection, with hominoids acquiring enhanced functions post-duplication from ECP (RNASE3) :
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Key Evolutionary Events:
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Saguinus oedipus retains ancestral traits, reflecting weaker selective pressure for antiviral adaptation .
Research Gaps and Future Directions
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Functional Studies: Direct characterization of recombinant Saguinus oedipus RNASE2 is needed to confirm inferred properties.
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Structural Modeling: Molecular dynamics simulations could clarify how NW monkey-specific residues alter substrate binding.
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Comparative Immunology: Assess whether NW monkey RNASE2 compensates for antiviral deficits via alternative mechanisms (e.g., immune cell recruitment) .
