Atomic structures and reaction mechanisms of proteins involved in transfer and insertion of molybdenum cofactor and heme
Final Report Abstract
We had the ambitious goal of getting involved in four projects and aimed for a total of at least eight structures to be solved. We achieved this goal partly. The greatest success we had with the structural studies on the E-domain of the Cnx1 protein. Here we managed to solve the structure of Cnx1E in complex with its one substrate molybdate and with Mg2+, which could be considered a metal cofactor for Cnx1E due to necessity of its presence during the Cnx1E- catalyzed reaction. This structure gave experimental foundation to the identification of the Cnx1E active site. Further, it assigned a function to subdomain IV as molybdate binding region and offered an explanation why certain variants show reduced enzyme activity. The localization of the corresponding amino acid positions hinted at a link between Cnx1E dimerization and enzymatic activity. We were also involved in the groundbreaking structure determination of MPT-AMP accumulating Cnx1E variants and the identification of adenylated Moco as a novel intermediate of Moco biosynthesis. Our involvement in the other projects, however, was less successful. Although we managed to purify and crystallize NirN, the crystals did not diffract well enough for structure determination and it was not possible to grow better ones. The crystallization of Aba3 and HemW failed entirely due to problems with protein aggregation.
Publications
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(2016). Dimerization of the plant molybdenum insertase Cnx1E is required for synthesis of the molybdenum cofactor. Biochem. J.
Joern Krausze, Corinna Probst, Ute Curth, Joachim Reichelt, Sayantan Saha, David Schafflick, Dirk W. Heinz, Ralf R. Mendel, Tobias Kruse
