Structure and function of circadian clock proteins and deuterium isotope effects in nucleic acid hydrogen bonds

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dc.contributor.advisor LiWang , Andy C . en_US
dc.contributor.committeeMember Raushel , Frank M . en_US
dc.creator Vakonakis , Ioannis en_US
dc.date.accessioned 2005 -08 -29T14 :35 :19Z
dc.date.accessioned 2014 -02 -19T19 :20 :09Z
dc.date.available 2005 -08 -29T14 :35 :19Z
dc.date.available 2014 -02 -19T19 :20 :09Z
dc.date.created 2003 -05 en_US
dc.date.issued 2005 -08 -29T14 :35 :19Z
dc.identifier.uri http : / /hdl .handle .net /1969 .1 /2195
dc.description.abstract Circadian oscillators or clocks are a widespread , endogenous class of oscillatory mechanisms that control the ~24h temporal pattern of diverse organism functions . In cyanobacteria this mechanism is formed by three proteins , KaiA , KaiB and KaiC . KaiA is shown here to be a two domain protein that directly interacts with KaiC and enhances the KaiC autokinase activity . The amino -terminal domain of KaiA can be structurally categorized as a pseudo -receiver , a class of proteins used in signaling cascades and activated by direct protein ? ?protein interactions . The carboxy -terminal domain interacts directly with KaiC , is sufficient to enhance the KaiC autokinase activity in a manner similar to full -length KaiA , and adopts a unique , all & #945 ; -helical dimeric fold . The structure of this domain raises interesting probabilities regarding the mode of KaiA ? ?KaiC interaction . The two KaiA domains are shown to directly interact with each other , which suggests a possible mechanism of signal transfer from the amino to carboxy -terminal domain . Hydrogen bonds are of paramount importance in nucleic acid structure and function . Here we show that changes in the width and anharmonicity of vibrational potential energy wells of hydrogen bonded groups can be measured in nucleic acids and can possibly be correlated to structural properties , such as length . Deuterium /protium fractionation factors , which are sensitive to the vibrational potential well width , were measured for the imino sites of thymidine residues involved in A :T base pairs or free in solution , and a correlation was established between decreasing fractionation factors and increasing imino proton chemical shift , & #948 ;H3 . Similarly , a correlation was observed between & #948 ;H3and deuterium isotope effects (DIE ) on chemical shift of thymidine carbon atoms . Combined these results indicate that as hydrogen -bond strength increases the vibrational potential wells of imino protons widen with a corresponding increase in anharmonicity . However , trans -hydrogen bond DIE on carbon chemical shifts of A :T base -paired adenosine residues do not correlate with those measured on thymidine residues . We propose that this lack of correlation is due to DIE dependence on base -pair geometry , which is not easily measured by traditional NMR experiments . en_US
dc.format.extent 12438330 bytes
dc.format.medium electronic en_US
dc.format.mimetype application /pdf
dc.language.iso en _US en_US
dc.publisher Texas A &M University en_US
dc.subject circadian clock en_US
dc.title Structure and function of circadian clock proteins and deuterium isotope effects in nucleic acid hydrogen bonds en_US
dc.type Book en
dc.type.genre Electronic Dissertation en_US
dc.type.material text en_US
dc.format.digitalOrigin born digital en_US

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Structure and function of circadian clock proteins and deuterium isotope effects in nucleic acid hydrogen bonds. Available electronically from http : / /hdl .handle .net /1969 .1 /2195 .

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