1T2I

T76W mutant of RNase Sa from Streptomyces aureofaciens


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.1 Å
  • R-Value Free: 0.167 
  • R-Value Work: 0.128 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Contribution of single tryptophan residues to the fluorescence and stability of ribonuclease sa.

Alston, R.W.Urbanikova, L.Sevcik, J.Lasagna, M.Reinhart, G.D.Scholtz, J.M.Pace, C.N.

(2004) Biophys.J. 87: 4036-4047

  • DOI: 10.1529/biophysj.104.050377
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • Ribonuclease Sa (RNase Sa) contains no tryptophan (Trp) residues. We have added single Trp residues to RNase Sa at sites where Trp is found in four other microbial ribonucleases, yielding the following variants of RNase Sa: Y52W, Y55W, T76W, and Y81W ...

    Ribonuclease Sa (RNase Sa) contains no tryptophan (Trp) residues. We have added single Trp residues to RNase Sa at sites where Trp is found in four other microbial ribonucleases, yielding the following variants of RNase Sa: Y52W, Y55W, T76W, and Y81W. We have determined crystal structures of T76W and Y81W at 1.1 and 1.0 A resolution, respectively. We have studied the fluorescence properties and stabilities of the four variants and compared them to wild-type RNase Sa and the other ribonucleases on which they were based. Our results should help others in selecting sites for adding Trp residues to proteins. The most interesting findings are: 1), Y52W is 2.9 kcal/mol less stable than RNase Sa and the fluorescence intensity emission maximum is blue-shifted to 309 nm. Only a Trp in azurin is blue-shifted to a greater extent (308 nm). This blue shift is considerably greater than observed for Trp71 in barnase, the Trp on which Y52W is based. 2), Y55W is 2.1 kcal/mol less stable than RNase Sa and the tryptophan fluorescence is almost completely quenched. In contrast, Trp59 in RNase T1, on which Y55W is based, has a 10-fold greater fluorescence emission intensity. 3), T76W is 0.7 kcal/mol more stable than RNase Sa, indicating that the Trp side chain has more favorable interactions with the protein than the threonine side chain. The fluorescence properties of folded Y76W are similar to those of the unfolded protein, showing that the tryptophan side chain in the folded protein is largely exposed to solvent. This is confirmed by the crystal structure of the T76W which shows that the side chain of the Trp is only approximately 7% buried. 4), Y81W is 0.4 kcal/mol less stable than RNase Sa. Based on the crystal structure of Y81W, the side chain of the Trp is 87% buried. Although all of the Trp side chains in the variants contribute to the unusual positive circular dichroism band observed near 235 nm for RNase Sa, the contribution is greatest for Y81W.


    Organizational Affiliation

    Department of Medical Biochemistry and Genetics, Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Guanyl-specific ribonuclease Sa
A
96Kitasatospora aureofaciensMutation(s): 1 
Gene Names: rnaSA
EC: 3.1.27.3
Find proteins for P05798 (Kitasatospora aureofaciens)
Go to UniProtKB:  P05798
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.1 Å
  • R-Value Free: 0.167 
  • R-Value Work: 0.128 
  • Space Group: P 21 21 21
Unit Cell:
Length (Å)Angle (°)
a = 33.872α = 90.00
b = 40.462β = 90.00
c = 56.638γ = 90.00
Software Package:
Software NamePurpose
DENZOdata reduction
MOLREPphasing
REFMACrefinement
SCALEPACKdata scaling

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2004-12-21
    Type: Initial release
  • Version 1.1: 2008-04-30
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance