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Sci. Signal., 27 April 2010
Vol. 3, Issue 119, p. ra33
[DOI: 10.1126/scisignal.2000800]

RESEARCH ARTICLES

Evolution of CASK into a Mg2+-Sensitive Kinase

Konark Mukherjee1*{dagger}, Manu Sharma1, Reinhard Jahn2, Markus C. Wahl3{dagger}, and Thomas C. Südhof1{dagger}

1 Department of Molecular and Cellular Physiology, Stanford University School of Medicine, 1050 Arastradero Road, Palo Alto, CA 94304, USA.
2 Neurobiologie, Max-Planck-Institut für Biophysikalische Chemie, Am Faßberg 11, D-37077 Göttingen, Germany.
3 Fachbereich Biologie, Chemie, Pharmazie, Institut für Chemie und Biochemie, AG Strukturbiochemie, Freie Universität Berlin, Takustrasse 6, D-14195 Berlin, Germany.

* Present address: Biology Department, Brandeis University, MS008, 415 South Street, Waltham, MA 02454–9110, USA.

Abstract: All known protein kinases, except CASK [calcium/calmodulin (CaM)–activated serine-threonine kinase], require magnesium ions (Mg2+) to stimulate the transfer of a phosphate from adenosine 5'-triphosphate (ATP) to a protein substrate. The CaMK (calcium/calmodulin-dependent kinase) domain of CASK shows activity in the absence of Mg2+; indeed, it is inhibited by divalent ions including Mg2+. Here, we converted the Mg2+-inhibited wild-type CASK kinase (CASKWT) into a Mg2+-stimulated kinase (CASK4M) by substituting four residues within the ATP-binding pocket. Crystal structures of CASK4M with and without bound nucleotide and Mn2+, together with kinetic analyses, demonstrated that Mg2+ accelerates catalysis of CASK4M by stabilizing the transition state, enhancing the leaving group properties of adenosine 5'-diphosphate, and indirectly shifting the position of the {gamma}-phosphate of ATP. Phylogenetic analysis revealed that the four residues conferring Mg2+-mediated stimulation were substituted from CASK during early animal evolution, converting a primordial, Mg2+-coordinating form of CASK into a Mg2+-inhibited kinase. This emergence of Mg2+ sensitivity (inhibition by Mg2+) conferred regulation of CASK activity by divalent cations, in parallel with the evolution of the animal nervous systems.

{dagger} To whom correspondence should be addressed. E-mail: konark{at}brandeis.edu (K.M.); mwahl{at}chemie.fu-berlin.de (M.C.W.); tcs1{at}stanford.edu (T.C.S.)

Citation: K. Mukherjee, M. Sharma, R. Jahn, M. C. Wahl, T. C. Südhof, Evolution of CASK into a Mg2+-Sensitive Kinase. Sci. Signal. 3, ra33 (2010).

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