VOLUME 286 (2011) PAGES 38079–38085
This article has been withdrawn by the authors.
In the original manuscript, the results of E338A and E366A mutants were reversed. We transformed Escherichia coli BL21 (λDE3) cells with the E366A plasmid instead of the E338A plasmid when sample tubes were switched inadvertently. The correct E338A and E366A mutants were expressed, purified, and characterized again. The results showed that Glu-338, and not Glu-366, is critical for catalytic activity. We wish to withdraw the manuscript and submit a corrected manuscript. We apologize for any inconvenience caused by this error.