Soluble guanylate cyclase（sGC） is a critical heme-containing enzyme involved in NO signaling.The dimerization of sGC subunits is necessary for its bioactivity and its mechanism is a striking and an indistinct issue.The roles of heme domain cysteines of the sGC on the dimerization and heme binding were investigated herein.The site-directed mutations of three conserved cysteines（C78A,C122A and C174S） were studied systematically and the three mutants were characterized by gel filtration analysis,UV-vis spectroscopy and heme transfer examination.Cys78 was involved in heme binding but not referred to the dimerization,while Cys174 was demonstrated to be involved in the homodimerization.These results provide new insights into the cysteine-related dimerization regulation of sGC.
Fang Fang ZhongXiao Xiao LiuJie PanZhong Xian HuangXiang Shi Tan
The human pathogen Clostridium difficile infection（CDI） is one of the most important healthcare- associated infections. Methyltransferase（MeTrca） and corrinoid iron-sulfur protein（CoFeSPca） are two key proteins in the acetyl-coenzyme A synthesis pathway of Clostridium difficile, which is essential for the survival of the pathogen and is absent in humans. Hence, the interaction between MeTrca and CoFeSPcd can become innovative targets for the treatment of human CDI. In this study, the interaction between MeTrca and CoFeSPca was verified by fluorescence resonance energy transfer measurements. The influence of the interaction on the tertiary structure of MeTrcd and CoFeSPcd was studied by ANS-labeled fluorescence measurements. Molecular docking was also performed to understand the mechanism of the protein interactions. These results provide a molecular basis for innovative drug design and development to treat human CDI.
