117 research outputs found
Replacement of His23 by Cys in a zinc finger of HIV-1 NCp7 led to a change in 1H NMR-derived 3D structure and to a loss of biological activity
AbstractThe nucleocapsid protein NCp7 of human immunodeficiency virus type 1 (HIV-1), which is necessary for the formation of infectious virions, contains two zinc fingers of the Cys-X2-Cys-X4-His-X4-Cys form. To elucidate the importance of this particular motif, well conserved in retroviruses and retroelements, we substituted the histidine residue by a cysteine in the first zinc binding domain 13VKCFNCGKEGHTARNCRA30. The structures of the mutated and native zinc complexed peptides were studied by two-dimensional 600 MHz 1H nuclear magnetic resonance (NMR) in aqueous solution. The nuclear Overhauser effects were used as constraints to determine the solution structures using DIANA software followed by AMBER energy refinement. The results show that native and mutant peptides fold into non-identical three-dimensional structures, probably accounting for the loss of retrovirus infectivity following the His-Cys point mutation
Limit theorems for von Mises statistics of a measure preserving transformation
For a measure preserving transformation of a probability space
we investigate almost sure and distributional convergence
of random variables of the form where (called the \emph{kernel})
is a function from to and are appropriate normalizing
constants. We observe that the above random variables are well defined and
belong to provided that the kernel is chosen from the projective
tensor product with We establish a form of the individual ergodic theorem for such
sequences. Next, we give a martingale approximation argument to derive a
central limit theorem in the non-degenerate case (in the sense of the classical
Hoeffding's decomposition). Furthermore, for and a wide class of
canonical kernels we also show that the convergence holds in distribution
towards a quadratic form in independent
standard Gaussian variables . Our results on the
distributional convergence use a --\,invariant filtration as a prerequisite
and are derived from uni- and multivariate martingale approximations
A chemosensory GPCR as a potential target to control the Root-Knot Nematode Meloidogyne incognita parasitism in plants.
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Leadership and style in the French Fifth Republic:Nicolas Sarkozy’s presidency in historical and cultural perspective
This article contributes to the body of the developing theoretical research in leadership and presidential studies by adding analysis of what I have termed ‘comportmental style’ as a factor in leader/follower relations. Within institutionalism and the wider structure/agency debate in political science, one of the challenges as regards the study of leadership is to identify factors that offer scope to or else militate against leaders’ performance. The comportmental style of Nicolas Sarkozy (President of the French Republic 2007–2012), deployed in the context of the – changing – institution of the presidency, was a major factor in his extreme unpopularity, and contributed to his defeat in 2012. What this tells us about the nature of the changing French presidency and the role of style will be discussed in the conclusion
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