1lav

STABILIZATION OF ESCHERICHIA COLI RIBONUCLEASE HI BY CAVITY-FILLING MUTATIONS WITHIN A HYDROPHOBIC CORESTABILIZATION OF ESCHERICHIA COLI RIBONUCLEASE HI BY CAVITY-FILLING MUTATIONS WITHIN A HYDROPHOBIC CORE

Structural highlights 1lav is a 1 chain structure with sequence from Escherichia coli. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Activity: Ribonuclease H, with EC number 3.1.26.4 Resources: FirstGlance, OCA, RCSB, PDBsum Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed The crystal structure of Escherichia coli ribonuclease HI has a cavity near Val-74 within the protein core. In order to fill the cavity space, we constructed two mutant proteins, V74L and V74I, in which Val-74 was replaced with either Leu or Ile, respectively. The mutant proteins are stabilized, as revealed by a 2.1-3.7 degrees C increase in the Tm values, as compared to the wild-type protein at pH values of 3.0 and 5.5. The mutant protein V74A, in which Val-74 is replaced with Ala, was also constructed to analyze the reverse effect. The stability of V74A decreases by 7.6 degrees C at pH 3.0 and 12.7 degrees C at pH 5.5 in Tm as compared to those values for the wild-type protein. None of the three mutations significantly affect the enzymatic activity. The crystal structures of V74L and V74I, determined at 1.8-A resolution, are almost identical to that of the wild-type protein, except for the mutation site. In the two mutant proteins, calculation by the Voronoi procedure shows that the cavity volumes around the individual mutation sites are remarkably reduced as compared to that in the wild-type protein. These results indicate that the introduction of a methylene group into the cavity, without causing steric clash, contributes to an increase in the hydrophobic interaction within the protein core and thereby enhances protein stability. We also discuss the role of the Leu side chain, which can assume many different local conformations on a helix without sacrificing thermostability. Stabilization of Escherichia coli ribonuclease HI by cavity-filling mutations within a hydrophobic core.,Ishikawa K, Nakamura H, Morikawa K, Kanaya S Biochemistry. 1993 Jun 22;32(24):6171-8. PMID:8390295 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Ribonuclease

spinqualitylabelsall models 1lav, resolution 1.80Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image