Probing the Communication between the Regulatory and Catalytic Domains of a Protein Tyrosine Kinase, Csk

Lin, Xiaofeng; Ayrapetov, Marina K.; Lee, Sungsoo; Parang, Keykavous; Sun, Gongqin

doi:10.1021/bi048142j

Cited by 31 publications

(42 citation statements)

References 33 publications

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“…Thus, remote docking interactions are likely a key part of the recognition mechanism. Our previous studies determined that Csk recognition of Src was not dependent on the Csk SH2 or SH3 domains (24); rather, Csk contained a substrate-docking site located in the peptide-binding lobe, centered on the ␣-helix D (15). In the current study, we identified several residues in the ␣-helix J of Src as the docking determinants recognized by the Csk substrate-docking site.…”

Section: Discussionmentioning

confidence: 99%

“…Thus, any factors that affect the catalytic activity of Csk could potentially affect Csk-Src recognition, even if such factors do not directly affect the physical interaction between Csk and Src. For example, Csk catalytic activity is positively regulated by the presence of its SH3 and SH2 domains (24) and the SH2 domain ligand (26). Such regulations could potentially affect the substrate recognition as well.…”

Section: Discussionmentioning

confidence: 99%

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Docking-based Substrate Recognition by the Catalytic Domain of a Protein Tyrosine Kinase, C-terminal Src Kinase (Csk)

Lee

Ayrapetov

Kemble

et al. 2006

Journal of Biological Chemistry

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Protein tyrosine kinases are key enzymes of mammalian signal transduction. Substrate specificity is a fundamental property that determines the specificity and fidelity of signaling by protein tyrosine kinases. However, how protein tyrosine kinases recognize the protein substrates is not well understood. C-terminal Src kinase (Csk) specifically phosphorylates Src family kinases on a C-terminal Tyr residue, which down-regulates their activities. We have previously determined that Csk recognizes Src using a substrate-docking site away from the active site. In the current study, we identified the docking determinants in Src recognized by the Csk substrate-docking site and demonstrated an interaction between the docking determinants of Src and the Csk substrate-docking site for this recognition. A similar mechanism was confirmed for Csk recognition of another Src family kinase, Yes. Although both Csk and MAP kinases used docking sites for substrate recognition, their docking sites consisted of different substructures in the catalytic domain. These results helped establish a docking-based substrate recognition mechanism for Csk. This model may provide a framework for understanding substrate recognition and specificity of other protein tyrosine kinases.The human genome contains ϳ500 genes for protein kinases, including ϳ100 protein tyrosine kinases (PTKs) 3 (1). PTKs are important mediators of signal transduction and key targets of anticancer drug discovery (2). They mediate cellular signaling by responding to upstream signals and phosphorylating protein substrates on Tyr residues. To send a regulatory signal to specific protein targets, each PTK phosphorylates only one or a few protein substrates on specific tyrosine residues. Thus, substrate specificity determines signaling specificity and fidelity and distinguishes one PTK from another (3).One of the best understood PTK regulatory systems is the regulation of Src family protein tyrosine kinases (SFKs) by phosphorylation of a Tyr on its C-terminal tail (4, 5). There are nine kinases in the Src family, and each one contains, from the N to the C terminus, a myristoylation motif, a unique region, an SH3 domain, an SH2 domain, a catalytic domain, and a regulatory C-terminal tail. The C-terminal tail contains a Tyr residue (Tyr-527 in avian Src) for phosphorylation by the C-terminal Src kinase (Csk) (6) and the Csk-homologous kinase (7). The phosphorylated tail Tyr binds to the SH2 domain intramolecularly (8, 9), which leads to inactivation of SFKs (10). Ever since the PTK-substrate relationship between Csk and Src families was established about 15 years ago, how Csk specifically recognizes Src family kinases and phosphorylates them on the C-terminal tail Tyr has been an intriguing question (11,12). This exemplifies the largely unanswered question of how PTKs recognize protein substrates in general.Although the Tyr residue for phosphorylation is located on the C-terminal tail of SFKs, SFKs are ϳ50,000-fold better substrates than peptides, mimicking the C-terminal tails (k...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Docking-based Substrate Recognition by the Catalytic Domain of a Protein Tyrosine Kinase, C-terminal Src Kinase (Csk)

Lee

Ayrapetov

Kemble

et al. 2006

Journal of Biological Chemistry

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“…2A) (LaFevre-Bernt et al 1998;Hawkins and Marcy 2001;Guo et al 2006;Joseph et al 2007b). Mutation of a well-conserved tryptophan residue in the Itk and Btk SH2-kinase linkers (W355 in Itk, W395 in Btk) results in a significant decrease in kinase activity (Lin et al 2005;Guo et al 2006;Joseph et al 2007b) whereas mutation of the corresponding tryptophan in the Src kinase Hck leads to a dramatic increase in the activity of that kinase (LaFevre-Bernt et al 1998). In this regard, Itk is similar to Csk (carboxy-terminal Src kinase), another tyrosine kinase comprised of the common SH3-SH2-Kinase cassette and regulated in a manner opposite that of Src (Huang et al 2009).…”

Section: Regulation Of Itk Activitymentioning

confidence: 99%

T-Cell Signaling Regulated by the Tec Family Kinase, Itk

Andreotti¹,

Schwartzberg²,

Joseph³

et al. 2010

Cold Spring Harbor Perspectives in Biology

209

228

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The Tec family tyrosine kinases regulate lymphocyte development, activation, and differentiation. In T cells, the predominant Tec kinase is Itk, which functions downstream of the T-cell receptor to regulate phospholipase C-g. This review highlights recent advances in our understanding of Itk kinase structure and enzymatic regulation, focusing on Itk protein domain interactions and mechanisms of substrate recognition. We also discuss the role of Itk in the development of conventional versus innate T-cell lineages, including both ab and gd T-cell subsets. Finally, we describe the complex role of Itk signaling in effector T-cell differentiation and the regulation of cytokine gene expression. Together, these data implicate Itk as an important modulator of T-cell signaling and function.

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“…[11] Since the SH2 domain is critical for maintaining efficient catalysis in Csk, [10,18] we wondered whether the oxidation state of the SH2 domain could influence strain energies within the Csk structure and, thus, provide theoretical grounds for understanding the effects of reducing agents on catalytic activity. To address this issue, we compared the normal modes and associated strain energies for Csk, both with and without disulfide bond formation between Cys122 and Cys164.…”

Section: Communication Between the Disulfide Bond And The Active Sitementioning

confidence: 99%

A Novel Disulfide Bond in the SH2 Domain of the C-terminal Src Kinase Controls Catalytic Activity

Mills

Whitford

Shaffer

et al. 2007

Journal of Molecular Biology

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SummaryThe SH2 domain of the C-terminal Src kinase [Csk] contains a unique disulfide bond not present in other known SH2 domains. To investigate whether this unusual disulfide bond could serve a novel function, the effects of disulfide bond formation on catalytic activity of the full-length protein and on the structure of the SH2 domain were investigated. The kinase activity of full-length Csk decreases by an order of magnitude upon formation of the disulfide bond in the distal SH2 domain. NMR spectra of the fully oxidized and fully reduced SH2 domains exhibit similar chemical shift patterns and are indicative of similar, well-defined tertiary structures. The solvent-accessible disulfide bond in the isolated SH2 domain is highly stable and far from the small lobe of the kinase domain. However, reduction of this bond results in chemical shift changes of resonances that map to a cluster of residues that extend from the disulfide bond across the molecule to a surface that is in direct contact with the small-lobe of the kinase domain in the intact molecule. Normal mode analyses and molecular dynamics calculations suggest that disulfide bond formation has large effects on residues within the kinase domain, most notably within the active-site cleft. Overall, the data indicate that reversible cross-linking of two cysteines in the SH2 domain greatly impacts catalytic function and domaindomain communication in Csk. KeywordsCsk; cysteine; disulfide; kinase; NMR; phosphorylation The Src family of tyrosine kinases [SFKs] 1 are modular enzymes responsible for controlling various aspects of cellular growth and differentiation.[1] SH3 and SH2 domains in the SFKs flank the kinase domain and repress catalytic activity through intrasteric constraints. Most notably, the SH2 domain interacts tightly with a phosphotyrosine in the C-terminus of the kinase domain, inducing a closed conformation that poorly phosphorylates protein substrates.

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Probing the Communication between the Regulatory and Catalytic Domains of a Protein Tyrosine Kinase, Csk

Cited by 31 publications

References 33 publications

Docking-based Substrate Recognition by the Catalytic Domain of a Protein Tyrosine Kinase, C-terminal Src Kinase (Csk)

Docking-based Substrate Recognition by the Catalytic Domain of a Protein Tyrosine Kinase, C-terminal Src Kinase (Csk)

T-Cell Signaling Regulated by the Tec Family Kinase, Itk

A Novel Disulfide Bond in the SH2 Domain of the C-terminal Src Kinase Controls Catalytic Activity

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