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How Intrinsic Molecular Dynamics Control Intramolecular Communication in Signal Transducers and Activators of Transcription Factor STAT5.

Langenfeld F, Guarracino Y, Arock M, Trouvé A, Tchertanov L - PLoS ONE (2015)

Bottom Line: Despite the overall folding similarity of STAT5 proteins, the MD conformations display specific structural and dynamical features for each protein, indicating first, sequence-encoded structural properties and second, phosphorylation-induced effects which contribute to local and long-distance structural rearrangements interpreted as allosteric event.These results add a new insight to the understanding of the crucial role of intrinsic molecular dynamics in mediating intramolecular signaling in STAT5.Two pockets, localized in close proximity to the phosphotyrosine-binding site and adjacent to the channel for communication pathways across STAT5, may constitute valid targets to develop inhibitors able to modulate the function-related communication properties of this signaling protein.

View Article: PubMed Central - PubMed

Affiliation: Laboratoire de Biologie et Pharmacologie Appliquée Ecole Normale Supérieure de Cachan, CNRS, Université Paris-Saclay, Cachan, France.

ABSTRACT
Signal Transducer and Activator of Transcription STAT5 is a key mediator of cell proliferation, differentiation and survival. While STAT5 activity is tightly regulated in normal cells, its constitutive activation directly contributes to oncogenesis and is associated with a broad range of hematological and solid tumor cancers. Therefore the development of compounds able to modulate pathogenic activation of this protein is a very challenging endeavor. A crucial step of drug design is the understanding of the protein conformational features and the definition of putative binding site(s) for such modulators. Currently, there is no structural data available for human STAT5 and our study is the first footprint towards the description of structure and dynamics of this protein. We investigated structural and dynamical features of the two STAT5 isoforms, STAT5a and STAT5b, taken into account their phosphorylation status. The study was based on the exploration of molecular dynamics simulations by different analytical methods. Despite the overall folding similarity of STAT5 proteins, the MD conformations display specific structural and dynamical features for each protein, indicating first, sequence-encoded structural properties and second, phosphorylation-induced effects which contribute to local and long-distance structural rearrangements interpreted as allosteric event. Further examination of the dynamical coupling between distant sites provides evidence for alternative profiles of the communication pathways inside and between the STAT5 domains. These results add a new insight to the understanding of the crucial role of intrinsic molecular dynamics in mediating intramolecular signaling in STAT5. Two pockets, localized in close proximity to the phosphotyrosine-binding site and adjacent to the channel for communication pathways across STAT5, may constitute valid targets to develop inhibitors able to modulate the function-related communication properties of this signaling protein.

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Pockets detected at the STAT5 surface.(A) Two pockets (brown contours) are located in LD (in green) and SH2 (in yellow) domains; the key residues, K600, R618, S620 and S622, are shown as sticks. (B) Sequence conservation (+)/variability (-) between STAT5 and other STAT proteins. (C) The pockets volume was monitored over MD simulations of each STAT5. STAT5a is in blue, pSTAT5a is in yellow, STAT5b is in green and p-STAT5b is in magenta. The two replicas, 1 and 2, for each protein are distinguished by solid and dashed lines, respectively.
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pone.0145142.g009: Pockets detected at the STAT5 surface.(A) Two pockets (brown contours) are located in LD (in green) and SH2 (in yellow) domains; the key residues, K600, R618, S620 and S622, are shown as sticks. (B) Sequence conservation (+)/variability (-) between STAT5 and other STAT proteins. (C) The pockets volume was monitored over MD simulations of each STAT5. STAT5a is in blue, pSTAT5a is in yellow, STAT5b is in green and p-STAT5b is in magenta. The two replicas, 1 and 2, for each protein are distinguished by solid and dashed lines, respectively.

Mentions: The protein surface at proximity of these functionally crucial residues in STAT5 was carefully investigated with MDpocket [57]. We identified two adjacent pockets, P1 and P2, located between the LD and SH2 domains (Fig 9A). Pocket P1, circumscribed by helices α6 and α7, the loops linking these helices, and helix αA of SH2 domain, was found in all simulated proteins. The second pocket, P2, found in the SH2 domain between α-helix A and β-strands A-B, was also systematically observed, excepted in the second replica of non-phosphorylated STAT5a. These two pockets are separated by residues K600, R618, S620 and S622. Analysis of the residual conservation in proteins of STAT family indicates that residues at proximity to P2 are perfectly conserved while many residues formed P1 show the lower conservation level across STATs. (Fig 9B). Pocket P2 corresponds to the phosphotyrosine binding sub-pocket (pY+0) reported by Gianti et al. [58], and is targeted by most of the current STAT5-interacting molecules [41]. This site, common in all STAT proteins, contributes to formation of the parallel functional dimers, which are well characterized by X-ray crystallography for STAT1 and STAT3 [12,15]. Significantly, the pocket P1 is clearly distinct from (pY+3) sub-pocket [58] or other described pockets in STATs, and, to the best of our knowledge, represents a novel putative ligand-binding site.


How Intrinsic Molecular Dynamics Control Intramolecular Communication in Signal Transducers and Activators of Transcription Factor STAT5.

Langenfeld F, Guarracino Y, Arock M, Trouvé A, Tchertanov L - PLoS ONE (2015)

Pockets detected at the STAT5 surface.(A) Two pockets (brown contours) are located in LD (in green) and SH2 (in yellow) domains; the key residues, K600, R618, S620 and S622, are shown as sticks. (B) Sequence conservation (+)/variability (-) between STAT5 and other STAT proteins. (C) The pockets volume was monitored over MD simulations of each STAT5. STAT5a is in blue, pSTAT5a is in yellow, STAT5b is in green and p-STAT5b is in magenta. The two replicas, 1 and 2, for each protein are distinguished by solid and dashed lines, respectively.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4696835&req=5

pone.0145142.g009: Pockets detected at the STAT5 surface.(A) Two pockets (brown contours) are located in LD (in green) and SH2 (in yellow) domains; the key residues, K600, R618, S620 and S622, are shown as sticks. (B) Sequence conservation (+)/variability (-) between STAT5 and other STAT proteins. (C) The pockets volume was monitored over MD simulations of each STAT5. STAT5a is in blue, pSTAT5a is in yellow, STAT5b is in green and p-STAT5b is in magenta. The two replicas, 1 and 2, for each protein are distinguished by solid and dashed lines, respectively.
Mentions: The protein surface at proximity of these functionally crucial residues in STAT5 was carefully investigated with MDpocket [57]. We identified two adjacent pockets, P1 and P2, located between the LD and SH2 domains (Fig 9A). Pocket P1, circumscribed by helices α6 and α7, the loops linking these helices, and helix αA of SH2 domain, was found in all simulated proteins. The second pocket, P2, found in the SH2 domain between α-helix A and β-strands A-B, was also systematically observed, excepted in the second replica of non-phosphorylated STAT5a. These two pockets are separated by residues K600, R618, S620 and S622. Analysis of the residual conservation in proteins of STAT family indicates that residues at proximity to P2 are perfectly conserved while many residues formed P1 show the lower conservation level across STATs. (Fig 9B). Pocket P2 corresponds to the phosphotyrosine binding sub-pocket (pY+0) reported by Gianti et al. [58], and is targeted by most of the current STAT5-interacting molecules [41]. This site, common in all STAT proteins, contributes to formation of the parallel functional dimers, which are well characterized by X-ray crystallography for STAT1 and STAT3 [12,15]. Significantly, the pocket P1 is clearly distinct from (pY+3) sub-pocket [58] or other described pockets in STATs, and, to the best of our knowledge, represents a novel putative ligand-binding site.

Bottom Line: Despite the overall folding similarity of STAT5 proteins, the MD conformations display specific structural and dynamical features for each protein, indicating first, sequence-encoded structural properties and second, phosphorylation-induced effects which contribute to local and long-distance structural rearrangements interpreted as allosteric event.These results add a new insight to the understanding of the crucial role of intrinsic molecular dynamics in mediating intramolecular signaling in STAT5.Two pockets, localized in close proximity to the phosphotyrosine-binding site and adjacent to the channel for communication pathways across STAT5, may constitute valid targets to develop inhibitors able to modulate the function-related communication properties of this signaling protein.

View Article: PubMed Central - PubMed

Affiliation: Laboratoire de Biologie et Pharmacologie Appliquée Ecole Normale Supérieure de Cachan, CNRS, Université Paris-Saclay, Cachan, France.

ABSTRACT
Signal Transducer and Activator of Transcription STAT5 is a key mediator of cell proliferation, differentiation and survival. While STAT5 activity is tightly regulated in normal cells, its constitutive activation directly contributes to oncogenesis and is associated with a broad range of hematological and solid tumor cancers. Therefore the development of compounds able to modulate pathogenic activation of this protein is a very challenging endeavor. A crucial step of drug design is the understanding of the protein conformational features and the definition of putative binding site(s) for such modulators. Currently, there is no structural data available for human STAT5 and our study is the first footprint towards the description of structure and dynamics of this protein. We investigated structural and dynamical features of the two STAT5 isoforms, STAT5a and STAT5b, taken into account their phosphorylation status. The study was based on the exploration of molecular dynamics simulations by different analytical methods. Despite the overall folding similarity of STAT5 proteins, the MD conformations display specific structural and dynamical features for each protein, indicating first, sequence-encoded structural properties and second, phosphorylation-induced effects which contribute to local and long-distance structural rearrangements interpreted as allosteric event. Further examination of the dynamical coupling between distant sites provides evidence for alternative profiles of the communication pathways inside and between the STAT5 domains. These results add a new insight to the understanding of the crucial role of intrinsic molecular dynamics in mediating intramolecular signaling in STAT5. Two pockets, localized in close proximity to the phosphotyrosine-binding site and adjacent to the channel for communication pathways across STAT5, may constitute valid targets to develop inhibitors able to modulate the function-related communication properties of this signaling protein.

Show MeSH
Related in: MedlinePlus