7 resultados para unique school of medcine

em Indian Institute of Science - Bangalore - Índia


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Analysis of 35S labled nucleosides prepared from tRNA of Pseudomonas aeruginosa by phosphocellulose column chromatography, thin layer chromatography and Sephadex LH-20 column chromatography revealed the presence of 2-methylthioribosylzeatin in it. 2iPA, 6-(3-methyl-2-butenylamino)-9-β-D-ribofuranosyl purine; ms-2iPA, 6-(3-methyl-2-butenylamino)-2-methylthio-9-β-D-ribofuranosylpurine; ribosyl-cis-zeatin, 6-(4-hydroxy-3-methyl-cis-2-butenylamino)-9-β-D-ribofuranosylpurine; ribosyl-trans-zeatin, 6-(4-hydroxy-3-methyl-trans-2-butenylamino)-9-β-D-ribofuranosylpurine; ms-ribosylzeatin, 6-(4-hydroxy-3-methyl-2-butenylamino)-2-methylthio-9-β-D-ribofuranosylpurine; s4U2, 4-thiouridine; s2U*, 5-methylaminomethyl-2-thiouridine; s2C, 2-thiocytidine; TLC — thin layer chromatography.

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Analysis of 35S labled nucleosides prepared from tRNA of Pseudomonas aeruginosa by phosphocellulose column chromatography, thin layer chromatography and Sephadex LH-20 column chromatography revealed the presence of 2-methylthioribosylzeatin in it. 2iPA, 6-(3-methyl-2-butenylamino)-9-β-D-ribofuranosyl purine; ms-2iPA, 6-(3-methyl-2-butenylamino)-2-methylthio-9-β-D-ribofuranosylpurine; ribosyl-cis-zeatin, 6-(4-hydroxy-3-methyl-cis-2-butenylamino)-9-β-D-ribofuranosylpurine; ribosyl-trans-zeatin, 6-(4-hydroxy-3-methyl-trans-2-butenylamino)-9-β-D-ribofuranosylpurine; ms-ribosylzeatin, 6-(4-hydroxy-3-methyl-2-butenylamino)-2-methylthio-9-β-D-ribofuranosylpurine; s4U2, 4-thiouridine; s2U*, 5-methylaminomethyl-2-thiouridine; s2C, 2-thiocytidine; TLC — thin layer chromatography.

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Mycobacterium leprae, which has undergone reductive evolution leaving behind a minimal set of essential genes, has retained intervening sequences in four of its genes implicating a vital role for them in the survival of the leprosy bacillus. A single in-frame intervening sequence has been found embedded within its recA gene. Comparison of M. leprae recA intervening sequence with the known intervening sequences indicated that it has the consensus amino acid sequence necessary for being a LAGLIDADG-type homing endonuclease. In light of massive gene decay and function loss in the leprosy bacillus, we sought to investigate whether its recA intervening sequence encodes a catalytically active homing endonuclease. Here we show that the purified M. leprae RecA intein (PI-MleI) binds to cognate DNA and displays endonuclease activity in the presence of alternative divalent cations, Mg2+ or Mn2+. A combination of approaches including four complementary footprinting assays such as DNase I, Cu/phenanthroline, methylation protection and KMnO4, enhancement of 2-aminopurine fluorescence and mapping of the cleavage site revealed that PI-MleI binds to cognate DNA flanking its insertion site, induces helical distortion at the cleavage site and generates two staggered double-strand breaks. Taken together, these results implicate that PI-MleI possess a modular structure with separate domains for DNA target recognition and cleavage, each with distinct sequence preferences. From a biological standpoint, it is tempting to speculate that our findings have implications for understanding the evolution of LAGLIDADG family of homing endonucleases

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The paper describes egg laying and reproduction in ICHTHYOPHIS MALABARENSIS. 100 eggs, the largest ever in Apoda, are laid in a single string and manipulated by the female into a massive clutch. The reproductive strategies in the species are discussed.

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Metallophosphoesterase-domain-containing protein 2 (MPPED2) is a highly evolutionarily conserved protein with orthologs found from worms to humans. The human MPPED2 gene is found in a region of chromosome 11 that is deleted in patients with WAGR (Wilms tumor, aniridia, genitourinary anomalies, and mental retardation) syndrome, and MPPED2 may function as a tumor suppressor. However, the precise cellular roles of MPPED2 are unknown, and its low phosphodiesterase activity suggests that substrate hydrolysis may not be its prime function. We present here the structures of MPPED2 and two mutants, which show that the poor activity of MPPED2 is not only a consequence of the substitution of an active-site histidine residue by glycine but also due to binding of AMP or GMP to the active site. This feature, enhanced by structural elements of the protein, allows MPPED2 to utilize the conserved phosphoprotein-phosphatase-like fold in a unique manner, ensuring that its enzymatic activity can be combined with a possible role as a scaffolding or adaptor protein. (C) 2011 Elsevier Ltd. All rights reserved.

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Deoxyhypusine hydroxylase (DOHH) catalyzes the final step in the post-translational synthesis of an unusual amino acid hypusine (N-(sic)-(4-amino-2-hydroxybutyl) lysine), which is present on only one cellular protein, eukaryotic initiation factor 5A (eIF5A). We present here the molecular and structural basis of the function of DOHH from the protozoan parasite, Leishmania donovani, which causes visceral leishmaniasis. The L. donovani DOHH gene is 981 bp and encodes a putative polypeptide of 326 amino acids. DOHH is a HEAT-repeat protein with eight tandem repeats of alpha-helical pairs. Four conserved histidine-glutamate sequences have been identified that may act as metal coordination sites. A similar to 42 kDa recombinant protein with a His-tag was obtained by heterologous expression of DOHH in Escherichia coli. Purified recombinant DOHH effectively catalyzed the hydroxylation of the intermediate, eIF5A-deoxyhypusine (eIF5A-Dhp), in vitro. L. donovani DOHH (LdDOHH) showed similar to 40.6% sequence identity with its human homolog. The alignment of L. donovani DOHH with the human homolog shows that there are two significant insertions in the former, corresponding to the alignment positions 159-162 (four amino acid residues) and 174-183 (ten amino acid residues) which are present in the variable loop connecting the N- and C-terminal halves of the protein, the latter being present near the substrate binding site. Deletion of the ten-amino-acid-long insertion decreased LdDOHH activity to 14% of the wild type recombinant LdDOHH. Metal chelators like ciclopirox olamine (CPX) and mimosine significantly inhibited the growth of L. donovani and DOHH activity in vitro. These inhibitors were more effective against the parasite enzyme than the human enzyme. This report, for the first time, confirms the presence of a complete hypusine pathway in a kinetoplastid unlike eubacteria and archaea. The structural differences between the L. donovani DOHH and the human homolog may be exploited for structure based design of selective inhibitors against the parasite.

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Consider the domain E in defined by This is called the tetrablock. This paper constructs explicit boundary normal dilation for a triple (A, B, P) of commuting bounded operators which has as a spectral set. We show that the dilation is minimal and unique under a certain natural condition. As is well-known, uniqueness of minimal dilation usually does not hold good in several variables, e.g., Ando's dilation is known to be not unique, see Li and Timotin (J Funct Anal 154:1-16, 1998). However, in the case of the tetrablock, the third component of the dilation can be chosen in such a way as to ensure uniqueness.