Dataset Information

Altered dynamics in Lck SH3 upon binding to the LBD1 domain of Herpesvirus saimiri Tip.

ABSTRACT: The Tip protein from Herpesvirus saimiri interacts with the SH3 domain from the Src-family kinase Lck via a proline-containing sequence termed LBD1. Src-family kinase SH3 domains related to Lck have been shown to be dynamic in solution and partially unfold under physiological conditions. The rate of such partial unfolding is reduced by viral protein binding. To determine if the Lck SH3 domain displayed similar behavior, the domain was investigated with hydrogen exchange and mass spectrometry. Lck SH3 was found to be highly dynamic in solution. While other SH3 domains require as much as 10,000 sec to become totally deuterated, Lck SH3 became almost completely labeled within 200 sec. A partial unfolding event involving 8-10 residues was observed with a half-life of approximately 10 sec. Tip LBD1 binding did not cause gross structural changes in Lck SH3 but globally stabilized the domain and reduced the rate of partial unfolding by a factor of five. The region of partial unfolding in Lck SH3 was found to be similar to that identified for other SH3 domains that partially unfold. Although the sequence conservation between Lck SH3 and other closely related SH3 domains is high, the dynamics do not appear to be conserved.

SUBMITTER: Weis DD

PROVIDER: S-EPMC2242400 | biostudies-literature | 2006 Oct

REPOSITORIES: biostudies-literature

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Altered dynamics in Lck SH3 upon binding to the LBD1 domain of Herpesvirus saimiri Tip.

Weis David D DD Kjellen Peter P Sefton Bartholomew M BM Engen John R JR

Protein science : a publication of the Protein Society 20061001 10

The Tip protein from Herpesvirus saimiri interacts with the SH3 domain from the Src-family kinase Lck via a proline-containing sequence termed LBD1. Src-family kinase SH3 domains related to Lck have been shown to be dynamic in solution and partially unfold under physiological conditions. The rate of such partial unfolding is reduced by viral protein binding. To determine if the Lck SH3 domain displayed similar behavior, the domain was investigated with hydrogen exchange and mass spectrometry. Lc ...[more]

PMID: 17008721

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Project description:Lipid rafts are membrane microdomains that are proposed to function as platforms for both receptor signaling and trafficking. Our previous studies have demonstrated that Tip of herpesvirus saimiri (HVS), which is a T-lymphotropic tumor virus, is constitutively targeted to lipid rafts and interacts with cellular Lck tyrosine kinase and p80 WD repeat-containing endosomal protein. Through the interactions with Lck and p80, HVS Tip modulates diverse T-cell functions, which leads to the downregulation of T-cell receptor (TCR) and CD4 coreceptor surface expression, the inhibition of TCR signal transduction, and the activation of STAT3 transcription factor. In this study, we investigated the functional significance of Tip association with lipid rafts. We found that Tip expression remarkably increased lipid raft fractions in human T cells by enhancing the recruitment of lipid raft-resident proteins. Genetic analysis showed that the carboxyl-terminal transmembrane, but not p80 and Lck interaction, of Tip was required for the lipid raft localization and that lipid raft localization of Tip was necessary for the efficient downregulation of TCR and CD4 surface expression. Correlated with this, treatment with Filipin III, a lipid raft-disrupting agent, effectively reversed the downregulation of CD3 and CD4 surface expression induced by Tip. On the other hand, Tip mutants that were no longer present in lipid rafts were still capable of inhibiting TCR signaling and activating STAT3 transcription factor activity as efficiently as wild-type (wt) Tip. These results indicate that the association of Tip with lipid rafts is essential for the downregulation of TCR and CD4 surface expression but not for the inhibition of TCR signal transduction and the activation of STAT3 transcription factor. These results also suggest that the signaling and targeting activities of HVS Tip rely on functionally and genetically separable mechanisms, which may independently modulate T-cell function for viral persistence or pathogenesis.

Dataset Information

Altered dynamics in Lck SH3 upon binding to the LBD1 domain of Herpesvirus saimiri Tip.

Publications

Altered dynamics in Lck SH3 upon binding to the LBD1 domain of Herpesvirus saimiri Tip.

Similar Datasets

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