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Ribonuclease S

Contents 1 Ribonuclease S 2 Structure and Function 3 Mechanism 3.1 Dimer Formation 3.2 Dissociation of RNase S Dimers 4 references

spinqualitylabelsall models PDB ID 1d5h Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image
1d5h, resolution 2.25Å ()
Ligands:
Non-Standard Residues:
Related:	1rnv, 1d5d, 1d5e
Structural annotation: Resources: CATH : 1D5Hb00 InterPro : Ipr001427 Pfam : PF00074 SCOP : d1d5h.1 UniProt : P61823
Functional annotation: Molecular function: endonuclease activity hydrolase activity nuclease activity nucleic acid binding pancreatic ribonuclease activity protein binding
Evolutionary conservation: Toggle Conservation Colors: Rows = identical sequences: Further Information: Caveats, Explanation, Complete Results at ConSurfDB
Resources:	FirstGlance, OCA, PDBsum, RCSB
Coordinates:	save as pdb, mmCIF, xml

Ribonuclease S Ribonuclease A ^[1]

Structure and Function

RNase S is composed of two fragments: the small fragment, S-peptide (residues 1-20), and the large fragment, S-protein (residues 21-124)^[2]. These fragments remain tightly bound by non-covalent interactions^[3]. The only observed change in covalent structure during the conversion of RNase A to RNase S is the hydrolysis of the peptide bond between the residues 20 and 21 (REF). This complex (RNase S) conserves the catalytic activity and native conformation of uncleaved RNase A, but shows a reduced conformational stability^[4]. It has four disulfide bonds that impose rigidity to the protein^[4]. The dimer has a trans Asn113-Pro114 peptide bond in the hinge loop, whereas the monomer has a cis bond in this position^[4].

Mechanism

Dimer Formation

Dissociation of RNase S Dimers

references

1. ↑ Watkins RW, Arnold U, Raines RT. Ribonuclease S redux. Chem Commun (Camb). 2011 Jan 21;47(3):973-5. Epub 2010 Nov 16. PMID:21079871 doi:10.1039/c0cc03864d
2. ↑ Ratnaparkhi GS, Varadarajan R. Thermodynamic and structural studies of cavity formation in proteins suggest that loss of packing interactions rather than the hydrophobic effect dominates the observed energetics. Biochemistry. 2000 Oct 10;39(40):12365-74. PMID:11015216
3. ↑ Lopez-Alonso JP, Bruix M, Font J, Ribo M, Vilanova M, Rico M, Gotte G, Libonati M, Gonzalez C, Laurents DV. Formation, structure, and dissociation of the ribonuclease S three-dimensional domain-swapped dimer. J Biol Chem. 2006 Apr 7;281(14):9400-6. Epub 2006 Jan 16. PMID:16415350 doi:10.1074/jbc.M510491200
4. ↑ ^{4.0 4.1 4.2} . Two hydrophobic residues, methionine 13 and phenylalanine 8, of the S-peptide contribute significantly to the stability of RNase S,<ref></ref> while three residues (Phe 8, His 12, and Met 13) seem to be essential for the for the formation of the catalytically active RNase S<ref> PMID:8453373</li></ol></ref>