Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Pivot Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Target Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Query: EC:3.1.27.3 (
RNase T1
)
1,228
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
The reoccurrence of water molecules in crystal structures of
RNase T1
was investigated. Five waters were found to be invariant in
RNase T1
as well as in six other related fungal RNases. The structural, dynamical, and functional characteristics of one of these conserved hydration sites (
WAT1
) were analyzed by protein engineering, X-ray crystallography, and (17)O and 2H nuclear magnetic relaxation dispersion (NMRD). The position of
WAT1
and its surrounding hydrogen bond network are unaffected by deletions of two neighboring side chains. In the mutant Thr93Gln, the Gln93N epsilon2 nitrogen replaces
WAT1
and participates in a similar hydrogen bond network involving Cys6, Asn9, Asp76, and Thr91. The ability of
WAT1
to form four hydrogen bonds may explain why evolution has preserved a water molecule, rather than a side-chain atom, at the center of this intricate hydrogen bond network. Comparison of the (17)O NMRD profiles from wild-type and Thr93Gln
RNase T1
yield a mean residence time of 7 ns at 27 degrees C and an orientational order parameter of 0.45. The effects of mutations around
WAT1
on the kinetic parameters of
RNase T1
are small but significant and probably relate to the dynamics of the active site.
...
PMID:Dissection of the structural and functional role of a conserved hydration site in RNase T1. 1021 18
Buried and well-ordered solvent molecules are an integral part of each folded protein. For a few individual water molecules, the exchange kinetics with solvent have been described in great detail. So far, little is known about the energetics of this exchange process. Here, we present an experimental approach to investigate water-mediated intramolecular protein-protein interactions by use of double mutant cycles. As a first example, we analyzed the interdependence of the contribution of two side chains (Asn9 and Thr93) to the conformational stability of
RNase T1
. In the folded state, both side chains are involved in the "solvation of the same water molecule
WAT1
. The coupling of the contributions of Asn9 and Thr93 to the conformational stability of
RNase T1
was measured by urea unfolding and differential scanning calorimetry. The structural integrity of each mutant was analyzed by X-ray crystallography. We find that the effects of the Asn9Ala and the Thr93Ala mutations on the conformational stability are additive in the corresponding double mutant. We conclude that the free energy of the
WAT1
mediated intramolecular protein-protein interaction in the folded state is very similar to solvent mediated protein-protein interaction in the unfolded state.
...
PMID:Analysis of a water mediated protein-protein interactions within RNase T1. 1082 76
