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Scientists at University of Tokyo, Medical Department report research in endonuclease
2009 OCT 19 - (NewsRx.com) -- According to recent research from Tokyo, Japan, "Archaeal splicing endonucleases (EndAs) are currently classified into three groups. Two groups require a single subunit protein to form a homodimer or homotetramer." "The third group requires two nonidentical protein components for the activity. To elucidate the molecular architecture of the two-subunit EndA system, we studied a crenarchaeal splicing endonuclease from Pyrobaculum aerophilum. In the present study, we solved a crystal structure of the enzyme at 1.7-A resolution. The enzyme adopts a heterotetrameric form composed of two catalytic and two structural subunits. By connecting the structural and the catalytic subunits of the heterotetrameric EndA, we could convert the enzyme to a homodimer that maintains the broad substrate specificity that is one of the characteristics of heterotetrameric EndA. Meanwhile, a deletion of six amino acids in a Crenarchaea-specific loop abolished the endonuclease activity even on a substrate with canonical BHB motif. These results indicate that the subunit architecture is not a major factor responsible for the difference of substrate specificity between single- and two-subunit EndA systems," wrote S. Yoshinari and colleagues, University of Tokyo, Medical Department. The researchers concluded: "Rather, the structural basis for the broad substrate specificity is built into the crenarchaeal splicing endonuclease itself." Yoshinari and colleagues published their study in Nucleic Acids Research (Functional importance of Crenarchaea-specific extra-loop revealed by an X-ray structure of a heterotetrameric crenarchaeal splicing endonuclease. Nucleic Acids Research, 2009;37(14):4787-4798). For additional information, contact S. Yoshinari, University of Tokyo, Graduate School Medical, Dept. of Biomedical Chemical, Bunkyo Ku, Tokyo 1130033, Japan. Publisher contact information for the journal Nucleic Acids Research is: Oxford University Press, Great Clarendon St., Oxford OX2 6DP, England. Keywords: Japan, Tokyo, Endonucleases, Enzyme Research, Enzymology, University of Tokyo, Medical Department. This article was prepared by Proteomics Weekly editors from staff and other reports. Copyright 2009, Proteomics Weekly via NewsRx.com.
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