Structural and functional insights into corrinoid iron-sulfur protein from human pathogen Clostridium difficile

The human pathogen Clostridium difficile infection (CDI) is one of the most important healthcare-associated infections. The Wood-Ljungdahl pathway, which is responsible for Acetyl-CoA biosynthesis, is essential for the survival of the pathogen and is absent in humans. The key proteins and enzymes involved in the pathway are attractive targets for the treatment of CDI. Corrinoid iron-sulfur protein (CoFeSP) is a key protein and acts as a methyl transformer in the Wood-Ljungdahl pathway. In this study, CoFeSP from Clostridium difficile (CoFeSPcd) was cloned, expressed in E. coli and characterized for the first time. The structure and function of CoFeSPcd were investigated using homology structure modeling, spectroscopy, electrochemistry, steady state/pre-steady state kinetics and molecular docldng. The two metal centers of CoFeSPcd, corrinoid cofactor and [4Fe-4S] cluster, were characterized using metal analysis, structural modeling, UV-Vis, EPR and direct electrochemistry. The methyl transfer activity between CH3-H(4)folate (CH3-THF) and CoFeSPcd catalyzed by methyl transferase (MeTrcd) was determined by kinetic studies. These results provide a molecular basis for innovative drug design and development to treat human CDI. (C) 2017 Elsevier Inc. All rights reserved.