1Z5F

Solution Structure of the Cytotoxic RC-RNase 3 with a Pyroglutamate Residue at the N-terminus

Summary for 1Z5F

• Entry DOI: 10.2210/pdb1z5f/pdb
• Related: 1KVZ
• NMR Information: BMRB: 5787
• Descriptor: RC-RNase 3 (1 entity in total)
• Functional Keywords: ribonuclease, pyroglutamate, cytotoxicity, bullfrog, hydrolase
• Biological source: Rana catesbeiana (bullfrog)
• Total number of polymer chains: 1
• Total formula weight: 11894.91

Authors

Lou, Y.C.,Huang, Y.C.,Pan, Y.R.,Chen, C.,Liao, Y.D. (deposition date: 2005-03-18, release date: 2006-02-28, Last modification date: 2024-10-23)

Primary citation

Lou, Y.C.,Huang, Y.C.,Pan, Y.R.,Chen, C.,Liao, Y.D.
Roles of N-terminal pyroglutamate in maintaining structural integrity and pKa values of catalytic histidine residues in bullfrog ribonuclease 3
J.Mol.Biol., 355:409-421, 2006

PubMed Abstract: Many proteins and bioactive peptides contain an N-terminal pyroglutamate residue (Pyr1). This residue reduces the susceptibility of the protein to aminopeptidases and often has important functional roles. The antitumor ribonuclease RC-RNase 3 (RNase 3) from oocytes of Rana catesbeiana (bullfrog) is one such protein. We have produced recombinant RNase 3 containing the N-terminal Pyr1 (pRNase 3) and found it to be indistinguishable from the native RNase 3 by mass spectrometry and a variety of other biochemical and immunological criteria. We demonstrated by NMR analysis that the Pyr1 of pRNase 3 forms hydrogen bonds with Lys9 and Ile96 and stabilizes the N-terminal alpha-helix in a rigid conformation. In contrast, the N-terminal alpha-helix becomes flexible and the pKa values of the catalytic residues His10 and His97 altered when Pyr1 formation is blocked by an extra methionine at the N terminus in the recombinant mqRNase 3. Thus, our results provide a mechanistic explanation on the essential role of Pyr1 in maintaining the structural integrity, especially at the N-terminal alpha-helix, and in providing the proper environment for the ionization of His10 and His97 residues for catalysis and cytotoxicity against HeLa cells.

PubMed: 16309702
DOI: 10.1016/j.jmb.2005.10.069

Experimental method

SOLUTION NMR