[Show abstract][Hide abstract] ABSTRACT: Iron is an essential metal for living organisms but its level must be strictly controlled in cells, because ferrous ion induces toxicity by generating highly active reactive oxygen, hydroxyl radicals, through the Fenton reaction. In addition, ferric ion shows low solubility under physiological conditions. To overcome these obstacles living organisms possess Ferritin superfamily proteins that are distributed in all three domains of life: bacteria, archaea, and eukaryotes. These proteins minimize hydroxyl radical formation by ferroxidase activity that converts Fe(2+) into Fe(3+) and sequesters iron by storing it as a mineral inside a protein cage. In this study, we discovered that mycobacterial DNA-binding protein 1 (MDP1), a histone-like protein, has similar activity to ferritin superfamily proteins. MDP1 prevented the Fenton reaction and protects DNA by the ferroxidase activity. The K(m) values of the ferroxidase activity by MDP1 of Mycobacterium bovis bacillus Calmette-Guérin (BCG-3007c), Mycobacterium tuberculosis (Rv2986c), and Mycobacterium leprae (ML1683; ML-LBP) were 0.292, 0.252, and 0.129 mM, respectively. Furthermore, one MDP1 molecule directly captured 81.4±19.1 iron atoms, suggesting the role of this protein in iron storage. This study describes for the first time a ferroxidase-iron storage protein outside of the ferritin superfamily proteins and the protective role of this bacterial protein from DNA damage.
[Show abstract][Hide abstract] ABSTRACT: Hepatocellular adenoma is a rare benign tumor of the liver. However, some complications, such as hemorrhage, rupture, and malignant transformation, have been reported previously. Surgical resection is considered to be the best choice of treatment, when adenomas are increasing in size, while resection is difficult to perform when multiple adenomas develop throughout the liver. Here, we report two cases of multiple hepatocellular adenomatosis. One patient had a history of aplastic anemia and the other had glycogen storage disease. We treated them with transcatheter arterial embolization (TAE) to prevent hemorrhage and rupture. After TAE, most parts of the adenomas showed necrotic change. These cases suggest that TAE is an effective treatment of hepatocellular adenomatosis.
Preview · Article · Jul 2009 · Hepatology International
[Show abstract][Hide abstract] ABSTRACT: Bacteria coordinate assembly of the cell wall as well as synthesis of cellular components depending on the growth state. The
mycobacterial cell wall is dominated by mycolic acids covalently linked to sugars, such as trehalose and arabinose, and is
critical for pathogenesis of mycobacteria. Transfer of mycolic acids to sugars is necessary for cell wall biogenesis and is
mediated by mycolyltransferases, which have been previously identified as three antigen 85 (Ag85) complex proteins. However,
the regulation mechanism which links cell wall biogenesis and the growth state has not been elucidated. Here we found that
a histone-like protein has a dual concentration-dependent regulatory effect on mycolyltransferase functions of the Ag85 complex
through direct binding to both the Ag85 complex and the substrate, trehalose-6-monomycolate, in the cell wall. A histone-like
protein-deficient Mycobacterium smegmatis strain has an unusual crenellated cell wall structure and exhibits impaired cessation of glycolipid biosynthesis in the growth-retarded
phase. Furthermore, we found that artificial alteration of the amount of the extracellular histone-like protein and the Ag85
complex changes the growth rate of mycobacteria, perhaps due to impaired down-regulation of glycolipid biosynthesis. Our results
demonstrate novel regulation of cell wall assembly which has an impact on bacterial growth.
Full-text · Article · Dec 2007 · Journal of bacteriology