1Q9E

RNase T1 variant with adenine specificity

Summary for 1Q9E

• Entry DOI: 10.2210/pdb1q9e/pdb
• Descriptor: Guanyl-specific ribonuclease T1 precursor, 2-AMINO-2-HYDROXYMETHYL-PROPANE-1,3-DIOL (3 entities in total)
• Functional Keywords: ribonuclease, hydrolase, adenine specificity
• Biological source: Aspergillus oryzae
• Total number of polymer chains: 3
• Total formula weight: 33633.52

Authors

Czaja, R.,Struhalla, M.,Hoeschler, K.,Saenger, W.,Straeter, N.,Hahn, U. (deposition date: 2003-08-25, release date: 2004-03-23, Last modification date: 2024-11-20)

Primary citation

Czaja, R.,Struhalla, M.,Saenger, W.,Hahn, U.
RNase T1 Variant RV Cleaves Single-Stranded RNA after Purines Due to Specific Recognition by the Asn46 Side Chain Amide.
Biochemistry, 43:2854-2862, 2004

PubMed Abstract: Attempts to alter the guanine specificity of ribonuclease T1 (RNase T1) by rational or random mutagenesis have failed so far. The RNase T1 variant RV (Lys41Glu, Tyr42Phe, Asn43Arg, Tyr45Trp, and Glu46Asn) designed by combination of a random and a rational mutagenesis approach, however, exhibits a stronger preference toward adenosine residues than wild-type RNase T1. Steady state kinetics of the cleavage reaction of the two dinucleoside phosphate substrates adenylyl-3',5'-cytidine and guanylyl-3',5'-cytidine revealed that the ApC/GpC ratio of the specificity coefficient (k(cat)/K(m)) was increased approximately 7250-fold compared to that of the wild-type. The crystal structure of the nucleotide-free RV variant has been refined in space group P6(1) to a crystallographic R-factor of 19.9% at 1.7 A resolution. The primary recognition site of the RV variant adopts a similar conformation as already known from crystal structures of RNase T1 not complexed to any nucleotide. Noteworthy is a high flexibility of Trp45 and Asn46 within the three individual molecules in the asymmetric unit. In addition to the kinetic studies, these data indicate the participation of Asn46 in the specific recognition of the base and therefore a specific binding of adenosine.

PubMed: 15005620
DOI: 10.1021/bi035961f

Experimental method

X-RAY DIFFRACTION (1.7 Å)