Biomedical subjects
Publications and source records attributed to Atsushi Minami.
Glycosyltransferase VinC was explored for a construction of glycoside libraries using dTDP-vicenisamine and structurally unrelated unnatural aglycons, and new unnatural vicenisaminides were successfully constructed. Structural elements of aglycon recognition by VinC were proposed by modeling studies and were confirmed by the success of transglycosylation upon a designed aglycon.
Vicenistatin, an antitumor antibiotic isolated from Streptomyces halstedii, is a unique 20-membered macrocyclic lactam with a novel aminosugar vicenisamine. The vicenistatin biosynthetic gene cluster (vin) spanning approximately 64 kbp was cloned and sequenced. The cluster contains putative genes for the aglycon biosynthesis including four modular polyketide synthases (PKSs), glutamate mutase, acyl CoA-ligase, and AMP-ligase. Also found in the cluster are genes of NDP-hexose 4,6-dehydratase and aminotransferase for vicenisamine biosynthesis. For the functional confirmation of the cluster, a putative glycosyltransferase gene product, VinC, was heterologously expressed, and the vicenisamine transfer reaction to the aglycon was chemically proved. A unique feature of the vicenistatin PKS is that the loading module contains only an acyl carrier protein domain, in contrast to other known PKS-loading modules containing certain activation domains. Activation of the starter acyl group by separate polypeptides is postulated as well.
BACKGROUND: Endoscopic sphincterotomy is used routinely for extraction of bile duct stones. Also, endoscopic papillary dilation is a safe and effective technique that significantly reduces the need for papillotomy. However, extraction of large and/or multiple stones after endoscopic papillary dilation can be difficult. A new technique, endoscopic metallic stent-lithotripsy, for treatment of bile duct stones without endoscopic sphincterotomy or endoscopic papillary dilation is described. METHODS: A self-expandable metallic stent was used to dilate the major duodenal papilla to allow lithotripsy and removal of bile duct stones in 38 patients. RESULTS: The bile duct was successfully cleared of stones in 36 cases (95%). Complications included one episode of mild pancreatitis and one of cholangitis. CONCLUSIONS: Although the number of patients who underwent successful expanding metallic stent-lithotripsy was small, the method is promising as an alternative to endoscopic sphincterotomy and endoscopic papillary dilation.
Plants have a unique transdifferentiation mechanism by which differentiated cells can initiate a new program of differentiation. We used a comprehensive analysis of gene expression in an in vitro zinnia (Zinnia elegans L.) culture model system to gather fundamental information about the gene regulation underlying the transdifferentiation of plant cells. In this model, photosynthetic mesophyll cells isolated from zinnia leaves transdifferentiate into xylem cells in a morphogenic process characterized by features such as secondary-wall formation and programmed cell death. More than 8,000 zinnia cDNA clones were isolated from an equalized cDNA library prepared from cultured cells transdifferentiating into xylem cells. Microarray analysis using these cDNAs revealed several types of unique gene regulation patterns, including: the transient expression of a set of genes during cell isolation, presumably induced by wounding; a rapid reduction in the expression of photosynthetic genes and the rapid induction of protein synthesis-associated genes during the first stage; the preferential induction of auxin-related genes during the subsequent stage; and the transient induction of genes closely associated with particular morphogenetic events, including cell-wall formation and degradation and programmed cell death during the final stage. This analysis also revealed a number of previously uncharacterized genes encoding proteins that function in signal transduction, such as protein kinases and transcription factors that are expressed in a stage-specific manner. These findings provide new clues to the molecular mechanisms of both plant transdifferentiation and wood formation.