Download MendeleyStructural analysis of an RNase T1 variant with an altered guanine binding segment.
Hoschler, K., Hoier, H., Hubner, B., Saenger, W., Orth, P., Hahn, U.(1999) J Mol Biology 294: 1231-1238
- PubMed: 10600381
- DOI: https://doi.org/10.1006/jmbi.1999.3324
- Primary Citation of Related Structures:
1CH0 - PubMed Abstract:
The ribonuclease T1 variant 9/5 with a guanine recognition segment, altered from the wild-type amino acid sequence 41-KYNNYE-46 to 41-EFRNWQ-46, has been cocrystallised with the specific inhibitor 2'-GMP. The crystal structure has been refined to a crystallographic R factor of 0.198 at 2.3 A resolution. Despite a size reduction of the binding pocket, pushing the inhibitor outside by 1 A, 2'-GMP is fixed to the primary recognition site due to increased aromatic stacking interactions. The phosphate group of 2'-GMP is located about 4.2 A apart from its position in wild-type ribonuclease T1-2'-GMP complexes, allowing a Ca(2+), coordinating this phosphate group, to enter the binding pocket. The crystallographic data can be aligned with the kinetic characterisation of the variant, showing a reduction of both, guanine affinity and turnover rate. The presence of Ca(2+) was shown to inhibit variant 9/5 and wild-type enzyme to nearly the same extent.
Organizational Affiliation:
Institut für Biochemie Fakultät für Biowissenschaften Pharmazie und Psychologie, Universität Leipzig, Talstrasse 33, Leipzig, 04103, Germany.
