1J1F

Crystal structure of the RNase MC1 mutant N71T in complex with 5'-GMP


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.6 Å
  • R-Value Free: 0.244 
  • R-Value Work: 0.221 

wwPDB Validation 3D Report Full Report


This is version 1.3 of the entry. See complete history

Literature

Crystal Structures of the Ribonuclease MC1 Mutants N71T and N71S in Complex with 5'-GMP: Structural Basis for Alterations in Substrate Specificity

Numata, T.Suzuki, A.Kakuta, Y.Kimura, K.Yao, M.Tanaka, I.Yoshida, Y.Ueda, T.Kimura, M.

(2003) Biochemistry 42: 5270-5278

  • DOI: 10.1021/bi034103g
  • Primary Citation of Related Structures:  1J1G, 1UCG

  • PubMed Abstract: 
  • Ribonuclease MC1 (RNase MC1), isolated from bitter gourd seeds, is a uridine specific RNase belonging to the RNase T2 family. Mutations of Asn71 in RNase MC1 to the amino acids Thr (N71T) and Ser (N71S) in guanosine preferential RNases altered the su ...

    Ribonuclease MC1 (RNase MC1), isolated from bitter gourd seeds, is a uridine specific RNase belonging to the RNase T2 family. Mutations of Asn71 in RNase MC1 to the amino acids Thr (N71T) and Ser (N71S) in guanosine preferential RNases altered the substrate specificity from uridine specific to guanosine specific, as shown by the transphosphorylation of diribonucleoside monophosphates [Numata, T., et al. (2001) Biochemistry 40, 524-530]. To elucidate the structural basis for the alteration of substrate specificity, crystal structures of the RNase MC1 mutants N71T and N71S, free or complexed with 5'-GMP, were determined at resolutions higher than 2 A. In the N71T-5'-GMP and N71S-5'-GMP complexes, the guanine moiety was, as in the case of the uracil moiety bound to wild-type RNase MC1, firmly stabilized in the B2 site by an extensive network of hydrogen bonds and hydrophobic interactions. Structure comparisons showed that mutations of Asn71 to Thr or Ser cause an enlargement of the B2 site, which then make it feasible to insert a guanine base into the B2 site of mutants N71T and N71S. This binding further allows for hydrogen bonding interaction of the side chain hydroxyl groups of Thr71 or Ser71 with the N7 atom of the guanine base. The mode of guanine binding of mutants N71T and N71S was found to be essentially identical to that of a guanosine preferential RNase NW from Nicotiana glutinosa. In particular, hydrogen bonds between the N7 atom of the guanine base and the hydroxyl groups of the amino acids at position 71 (RNase MC1 numbering) were completely conserved in three guanosine preferential enzymes, thereby indicating that the hydrogen bond may play an essential role in guanine binding in guanosine preferential RNases in the RNase T2 family. Consequently, it can be concluded that amino acids at position 71 (RNase MC1 numbering) serve as one of the determinants for substrate specificity (or preference) in the RNase T2 fimily by changing the size and shape of the B2 site.


    Related Citations: 
    • Crystal structures of the ribonuclease MC1 from bitter gourd seeds, complexed with 2'-UMP or 3'-UMP, reveal structural basis for uridine specificity
      Suzuki, A.,Yao, M.,Tanaka, I.,Numata, T.,Kikukawa, S.,Yamasaki, N.,Kimura, M.
      (2000) Biochem.Biophys.Res.Commun. 275: 572
    • Crystal structure of a ribonuclease from the seeds of bitter gourd (Momordica charantia) at 1.75 A resolution
      Nakagawa, A.,Tanaka, I.,Sakai, R.,Nakashima, T.,Funatsu, G.,Kimura, M.
      (1999) BIOCHIM.BIOPHYS.ACTA 1433: 253
    • Amino acid residues in ribonuclease MC1 from bitter gourd seeds which are essential for uridine specificity
      Numata, T.,Suzuki, A.,Yao, M.,Tanaka, I.,Kimura, M.
      (2001) BIOCHEMISTRY 40: 524


    Organizational Affiliation

    Laboratory of Biochemistry, Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School, Kyushu University, Fukuoka 812-8581, Japan. rinsei@agr.kyushu-u.ac.jp




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
RIBONUCLEASE MC1
A
191Momordica charantiaEC: 3.1.27.1
Find proteins for P23540 (Momordica charantia)
Go to UniProtKB:  P23540
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
5GP
Query on 5GP

Download SDF File 
Download CCD File 
A
GUANOSINE-5'-MONOPHOSPHATE
C10 H14 N5 O8 P
RQFCJASXJCIDSX-UUOKFMHZSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.6 Å
  • R-Value Free: 0.244 
  • R-Value Work: 0.221 
  • Space Group: P 21 21 21
Unit Cell:
Length (Å)Angle (°)
a = 38.375α = 90.00
b = 65.777β = 90.00
c = 75.882γ = 90.00
Software Package:
Software NamePurpose
CNSrefinement
SCALEPACKdata scaling
MAR345data collection
CNSphasing

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2003-05-20
    Type: Initial release
  • Version 1.1: 2008-04-27
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance
  • Version 1.3: 2017-10-04
    Type: Refinement description