1mgr
Crystal structure of RNase Sa3,cytotoxic microbial ribonuclease
OverviewOverview
Ribonuclease (RNase) Sa3 is secreted by the Gram-positive bacterium Streptomyces aureofaciens. The enzyme catalyzes the cleavage of RNA on the 3' side of guanosine residues. Here, x-ray diffraction analysis was used to determine the three-dimensional structure of two distinct crystalline forms of RNase Sa3 to a resolution of 2.0 and 1.7 A. These two structures are similar to each other as well as to that of a homolog, RNase Sa. All of the key active-site residues of RNase Sa (Asn(42), Glu(44), Glu(57), Arg(72), and His(88)) are located in the putative active site of RNase Sa3. Also herein, RNase Sa3 is shown to be toxic to human erythroleukemia cells in culture. Like onconase, which is an amphibian ribonuclease in Phase III clinical trials as a cancer chemotherapeutic, RNase Sa3 is not inhibited by the cytosolic ribonuclease inhibitor protein. Thus, a prokaryotic ribonuclease can be toxic to mammalian cells.
About this StructureAbout this Structure
1MGR is a Single protein structure of sequence from Streptomyces aureofaciens. Full crystallographic information is available from OCA.
ReferenceReference
X-ray structure of two crystalline forms of a streptomycete ribonuclease with cytotoxic activity., Sevcik J, Urbanikova L, Leland PA, Raines RT, J Biol Chem. 2002 Dec 6;277(49):47325-30. Epub 2002 Sep 11. PMID:12228255 Page seeded by OCA on Sat May 3 01:00:07 2008