Catalytic and regulatory domains of doublecortin kinase-1.
Doublecortin kinase-1 (DCK1) is a newly described multidomain protein kinase with a sequence significantly similar to those of both CaM kinases (CaMKs) and doublecortin, the product of the gene mutated in X-linked lissencephaly/double cortex syndrome, a severe developmental disorder of the nervous system. Functional studies have revealed microtubule binding and polymerization activities of the doublecortin domain, yet little is known regarding the enzymatic properties and regulation of the kinase catalytic domain. We have identified and report here notable similarities as well as differences between the catalytic and regulatory properties of DCK1 and those of the CaMKs. Using synthetic peptide substrates modeled on synapsin I, a substrate recognition motif for DCK1 of Hyd-Arg-Arg-X-X-Ser/Thr-Hyd was derived. The similarity of this motif to that of CaMKI [Lee, J. C., Kwon, Y.-G., Lawrence, D. S., and Edelman, A. M. (1994) Proc. Natl. Acad. Sci. U.S.A. 91, 6413-6417] is consistent with the 59% level of amino acid sequence similarity between their catalytic domains. DCK1 catalytic activity is enhanced by mutagenic introduction of negative charge at Thr-239, a residue in a position equivalent to that of Thr-177 of CaMKI, the activation loop site for regulation by CaM kinase kinase. Unlike CaMKs, DCK1 is not directly activated by Ca(2+)-bound CaM. However, truncation of a pseudosubstrate-like sequence in the C-terminus of DCK1 results in an approximately 6-fold enhancement of activity. Thus, DCK1 demonstrates the potential to be regulated by relief of autoinhibition in response to signal(s) distinct from Ca(2+)-bound CaM and potentially by activation loop phosphorylation and to phosphorylate intracellular targets at sites similar to those recognized by CaMK pathways.
Shang
Limin
L
Department of Pharmacology and Toxicology, State University of New York at Buffalo, Buffalo, New York 14214, USA.
Kwon
Young-Guen
YG
Nandy
Sandip
S
Lawrence
David S
DS
Edelman
Arthur M
AM
D000818:Animals; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D020134:Catalytic Domain / Q000235:genetics; D002460:Cell Line; D000089622:Doublecortin Domain Proteins; D000089662:Doublecortin Protein; D000089742:Doublecortin-Like Kinases; D004789:Enzyme Activation; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008869:Microtubule-Associated Proteins; D008870:Microtubules / Q000201:enzymology / Q000378:metabolism; D005810:Multigene Family; D016297:Mutagenesis, Site-Directed; D009419:Nerve Tissue Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D009479:Neuropeptides / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D009842:Oligopeptides / Q000737:chemistry / Q000378:metabolism; D010766:Phosphorylation; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D017346:Protein Serine-Threonine Kinases; D017434:Protein Structure, Tertiary / Q000235:genetics / Q000502:physiology; D051381:Rats; D013379:Substrate Specificity
C000714848:Dcx protein, rat; D000089622:Doublecortin Domain Proteins; D000089662:Doublecortin Protein; D047908:Intracellular Signaling Peptides and Proteins; D008869:Microtubule-Associated Proteins; D009419:Nerve Tissue Proteins; D009479:Neuropeptides; D009842:Oligopeptides; D020033:Protein Isoforms; C117347:DCLK1 protein, human; D000089742:Doublecortin-Like Kinases; C485526:Dclk1 protein, rat; D017346:Protein Serine-Threonine Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases