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- Title
Functional importance of crenarchaea-specific extra-loop revealed by an X-ray structure of a heterotetrameric crenarchaeal splicing endonuclease.
- Authors
Yoshinari, Shigeo; Shiba, Tomoo; Inaoka, Daniel-Ken; Itoh, Takashi; Kurisu, Genji; Harada, Shigeharu; Kita, Kiyoshi; Watanabe, Yoh-ichi
- Abstract
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. Rather, the structural basis for the broad substrate specificity is built into the crenarchaeal splicing endonuclease itself.
- Publication
Nucleic acids research, 2009, Vol 37, Issue 14, p4787
- ISSN
1362-4962
- Publication type
Journal Article
- DOI
10.1093/nar/gkp506