2E4L

Thermodynamic and Structural Analysis of Thermolabile RNase HI from Shewanella oneidensis MR-1

Summary for 2E4L

• Entry DOI: 10.2210/pdb2e4l/pdb
• Descriptor: Ribonuclease HI (2 entities in total)
• Functional Keywords: hydrolase, endoribonuclease, rnase hi, shewanella oneidensis mr-1
• Biological source: Shewanella oneidensis
• Cellular location: Cytoplasm (Potential): Q8EE30
• Total number of polymer chains: 1
• Total formula weight: 17807.36

Authors

Tadokoro, T.,You, D.J.,Chon, H.,Matsumura, H.,Koga, Y.,Takano, K.,Kanaya, S. (deposition date: 2006-12-13, release date: 2007-05-01, Last modification date: 2023-10-25)

Primary citation

Tadokoro, T.,You, D.J.,Abe, Y.,Chon, H.,Matsumura, H.,Koga, Y.,Takano, K.,Kanaya, S.
Structural, thermodynamic, and mutational analyses of a psychrotrophic RNase HI.
Biochemistry, 46:7460-7468, 2007

PubMed Abstract: Ribonuclease (RNase) HI from the psychrotrophic bacterium Shewanella oneidensis MR-1 was overproduced in Escherichia coli, purified, and structurally and biochemically characterized. The amino acid sequence of MR-1 RNase HI is 67% identical to that of E. coli RNase HI. The crystal structure of MR-1 RNase HI determined at 2.0 A resolution was highly similar to that of E. coli RNase HI, except that the number of intramolecular ion pairs and the fraction of polar surface area of MR-1 RNase HI were reduced compared to those of E. coli RNase HI. The enzymatic properties of MR-1 RNase HI were similar to those of E. coli RNase HI. However, MR-1 RNase HI was much less stable than E. coli RNase HI. The stability of MR-1 RNase HI against heat inactivation was lower than that of E. coli RNase HI by 19 degrees C. The conformational stability of MR-1 RNase HI was thermodynamically analyzed by monitoring the CD values at 220 nm. MR-1 RNase HI was less stable than E. coli RNase HI by 22.4 degrees C in Tm and 12.5 kJ/mol in DeltaG(H2O). The thermodynamic stability curve of MR-1 RNase HI was characterized by a downward shift and increased curvature, which results in an increased DeltaCp value, compared to that of E. coli RNase HI. Site-directed mutagenesis studies suggest that the difference in the number of intramolecular ion pairs partly accounts for the difference in stability between MR-1 and E. coli RNases HI.

PubMed: 17536836
DOI: 10.1021/bi7001423

Experimental method

X-RAY DIFFRACTION (2 Å)