G Comparison of the cofactors bound at the active sites of SiaB/SiaC and BsSpoIIAB/SpoIIAA complexes. For SiaB/SiaC complex, ADP, TPO68 of SaiC and Asn65 of SiaB are all shown as sticks in atomic colors (O, red; N, blue), whereas their C-atoms are colored in cyan, yellow and light blue, respectively. For BsSpoIIAB/SpoIIAA complex, ATP, Ala58 (mutation of Ser58) of SpoIIAA and Asn50 of SpoIIAB are all colored in white. Mg2+ ion and its coordinating water molecules are shown as spheres in green and red, respectively. 