01533nas a2200229   4500008004100000022001400041245016000055210006900215260009200284300001200376490000700388520061800395100001801013700002801031700001701059700001901076700002501095700002101120700001501141700002301156856012401179       2010                        eng d  a1744-309100aCrystallization and preliminary X-ray diffraction analysis of various enzyme-substrate complexes of isopropylmalate dehydrogenase from thermus thermophilus0 aCrystallization and preliminary Xray diffraction analysis of var  aCOMMERCE PLACE, 350 MAIN ST, MALDEN 02148, MA USAbWILEY-BLACKWELL PUBLISHING, INCcJUN  a738-7430 v663 a<p>The Thermus thermophilus 3-isopropylmalate dehydrogenase (Tt-IPMDH) enzyme catalyses the penultimate step of the leucine-biosynthesis pathway. It converts (2R,3S)-3-isopropylmalate to (2S)-2-isopropyl-3-oxosuccinate in the presence of divalent Mg(2+) or Mn(2+) and with the help of NAD(+). In order to elucidate the detailed structural and functional mode of the enzymatic reaction, crystals of Tt-IPMDH were grown in the presence of various combinations of substrate and/or cofactors. Here, the crystallization, data collection and preliminary crystallographic analyses of six such complexes are reported.</p>1 aMerli, Angelo1 aManikandan, Karuppasamy1 aGraczer, Eva1 aSchuldt, Linda1 aSingh, Rajesh, Kumar1 aZavodszky, Peter1 aVas, Maria1 aWeiss, Manfred, S.  uhttp://library.ncl.res.in/content/crystallization-and-preliminary-x-ray-diffraction-analysis-various-enzyme-substrate-002983nas a2200217   4500008004100000022001400041245012500055210006900180260011000249300001400359490000600373520212100379100001702500700001802517700002502535700002802560700002102588700002302609700001502632856011802647       2011                        eng d  a1742-206X00aAtomic level description of the domain closure in a dimeric enzyme: thermus thermophilus 3-isopropylmalate dehydrogenase0 aAtomic level description of the domain closure in a dimeric enzy  aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcMAR  a1646-16590 v73 a<p>The domain closure associated with the catalytic cycle is described at an atomic level, based on pairwise comparison of the X-ray structures of homodimeric Thermus thermophilus isopropylmalate dehydrogenase (IPMDH), and on their detailed molecular graphical analysis. The structures of the apo-form without substrate and in complex with the divalent metal-ion to 1.8 angstrom resolution, in complexes with both Mn(2+) and 3-isopropylmalate (IPM), as well as with both Mn(2+) and NADH, were determined at resolutions ranging from 2.0 to 2.5 angstrom. Single crystal microspectrophotometric measurements demonstrated the presence of a functionally competent protein conformation in the crystal grown in the presence of Mn(2+) and IPM. Structural comparison of the various complexes clearly revealed the relative movement of the two domains within each subunit and allowed the identification of two hinges at the interdomain region: hinge 1 between alpha d and beta F as well as hinge 2 between alpha h and beta E. A detailed analysis of the atomic contacts of the conserved amino acid side-chains suggests a possible operational mechanism of these molecular hinges upon the action of the substrates. The interactions of the protein with Mn(2+) and IPM are mainly responsible for the domain closure: upon binding into the cleft of the interdomain region, the substrate IPM induces a relative movement of the secondary structural elements beta E, beta F, beta G, alpha d and alpha h. A further special feature of the conformational change is the movement of the loop bearing the amino acid Tyr139 that precedes the interacting arm of the subunit. The tyrosyl ring rotates and moves by at least 5 angstrom upon IPM-binding. Thereby, new hydrophobic interactions are formed above the buried isopropyl-group of IPM. Domain closure is then completed only through subunit interactions: a loop of one subunit that is inserted into the interdomain cavity of the other subunit extends the area with the hydrophobic interactions, providing an example of the cooperativity between interdomain and intersubunit interactions.</p>1 aGraczer, Eva1 aMerli, Angelo1 aSingh, Rajesh, Kumar1 aKaruppasamy, Manikandan1 aZavodszky, Peter1 aWeiss, Manfred, S.1 aVas, Maria  uhttp://library.ncl.res.in/content/atomic-level-description-domain-closure-dimeric-enzyme-thermus-thermophilus-3-202106nas a2200181   4500008004100000245013000041210006900171260000800240300001000248490000600258520142600264100002501690700002301715700002101738700002001759700002001779856012501799       2018                        eng d00aOverexpression of mango alcohol dehydrogenase (MiADH1) mimics hypoxia in transgenic tomato and alters fruit flavor components0 aOverexpression of mango alcohol dehydrogenase MiADH1 mimics hypo  cMAR  a23-330 v73 aPlant alcohols and aldehydes are produced by the action of alcohol dehydrogenases (ADH) and play an important role during fruit ripening and aroma production. Alcohols are not only produced in different tissues at different stages of plant development but are also products of the fermentative pathway which gets activated by different stresses, including hypoxia. The ADH gene is a well-established marker for hypoxic response as well as plant aroma. In a previous report we have identified and characterized three ADHs (MiADH1, 2, 3) from Dashehari mango. MiADH1 was found to be fruit specific and was upregulated by ethylene and ABA, suggesting a role in fruit aroma volatile production. In order to functionally characterize MiADH1, transgenic tomato plants were developed under the control of the constitutive (CaMV35S) promoter. Transgenic tomato fruit expressing MiADH1 gene showed a change in the levels of several alcohols and aldehydes related to flavor in comparison to the control. The change in aroma and volatiles compounds was more prominent during the ripe stage as compared to unripe and mid-ripe stages of tomato fruit. The transgenic tomato plants also produced adventitious roots. Our results suggest that the overexpression of MiADH1 in tomato plants induced the fermentative pathway in roots, and mimicked hypoxic response by development of adventitious roots from the stem as an adaptive mechanism.1 aSingh, Rajesh, Kumar1 aSrivastava, Smriti1 aChidley, Hemangi1 aNath, Pravendra1 aSane, Vidhu, A.  uhttp://library.ncl.res.in/content/overexpression-mango-alcohol-dehydrogenase-miadh1-mimics-hypoxia-transgenic-tomato-and