Structural biology of the purine biosynthetic pathway |
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Authors: | Y Zhang M Morar S E Ealick |
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Institution: | (1) Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, NY 14853, USA |
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Abstract: | Purine biosynthesis requires ten enzymatic transformations to generate inosine monophosphate. PurF, PurD, PurL, PurM, PurC,
and PurB are common to all pathways, while PurN or PurT, PurK/PurE-I or PurE-II, PurH or PurP, and PurJ or PurO catalyze the
same steps in different organisms. X-ray crystal structures are available for all 15 purine biosynthetic enzymes, including
7 ATP-dependent enzymes, 2 amidotransferases and 2 tetrahydrofolate-dependent enzymes. Here we summarize the structures of
the purine biosynthetic enzymes, discuss similarities and differences, and present arguments for pathway evolution. Four of
the ATP-dependent enzymes belong to the ATP-grasp superfamily and 2 to the PurM superfamily. The amidotransferases are unrelated,
with one utilizing an N-terminal nucleophileglutaminase and the other utilizing a triad glutaminase. Likewise the tetrahydrofolate-dependent
enzymes are unrelated. Ancestral proteins may have included a broad specificity enzyme instead of PurD, PurT, PurK, PurC,
and PurP, and a separate enzyme instead of PurM and PurL.
Received 26 May 2008; received after revision 30 June 2008; accepted 9 July 2008 |
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Keywords: | " target="_blank"> Purine biosynthesis protein evolution ATP-grasp superfamily PurM superfamily amidotransferases |
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