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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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Comparison of the global dynamics by Normal Modes Analysis of STAT5 proteins.(A) The Cα atoms root mean square fluctuations as a function of residue number. Results for the two first modes are shown at top and bottom panels respectively, are denoted by color: STAT5a is in blue, pSTAT5a is in yellow, STAT5b is in green and p-STAT5b is in magenta. (B) First and second slowest motion modes illustrating atomic motions of STAT5a (top) and STAT5b (bottom). The STAT5 proteins displayed in cartoon representation are in light blue (STAT5a) and in dark blue (p-STAT5b). The atomic (Cα) components of each mode are drawn in red (first mode) and yellow (second mode) arrows. The length of arrows is positively correlated with motion magnitude and their orientation indicates motion direction. (C) Overlaps between the ten slowest modes of the phosphorylated and non-phosphorylated STAT5a (left) and STAT5b (right) are shown in the heatmap.
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pone.0145142.g005: Comparison of the global dynamics by Normal Modes Analysis of STAT5 proteins.(A) The Cα atoms root mean square fluctuations as a function of residue number. Results for the two first modes are shown at top and bottom panels respectively, are denoted by color: STAT5a is in blue, pSTAT5a is in yellow, STAT5b is in green and p-STAT5b is in magenta. (B) First and second slowest motion modes illustrating atomic motions of STAT5a (top) and STAT5b (bottom). The STAT5 proteins displayed in cartoon representation are in light blue (STAT5a) and in dark blue (p-STAT5b). The atomic (Cα) components of each mode are drawn in red (first mode) and yellow (second mode) arrows. The length of arrows is positively correlated with motion magnitude and their orientation indicates motion direction. (C) Overlaps between the ten slowest modes of the phosphorylated and non-phosphorylated STAT5a (left) and STAT5b (right) are shown in the heatmap.

Mentions: The square fluctuations of Cα atoms calculated from the first two NMA modes show that for all studied proteins, the mostly fluctuated residues are located in the distal CCD (Fig 5A). The amplitudes of the distal CCD fluctuations, explained by the first and second modes, are higher in p-STAT5a and STAT5b, than those observed in STAT5a and p-STAT5b. Other slow motions are observed in the p-Tail and in the solvent exposed loops of the linker and SH2 domains. Similarly to CCD, the fluctuations of the p-Tail residues are increased in STAT5b and p-STAT5a. This observation correlates with the square fluctuations behavior over the MD simulations. Computed scalar products between the first ten NMA modes from each pair of proteins (phosphorylated, p-STAT5 and non-phosphorylated, STAT5) indicate a good overlap between the two ensembles (Fig 5C). Namely, the modes intrinsically accessible in STAT5 are closely maintained in p-STAT5. Nevertheless, some differences are observed: while the modes 1–3 and 6–8 are maintained with an overlap of 0.7 or above in STAT5b, in STAT5a significantly fewer global modes (1–4, 7) are conserved, along with a weaker correlation and reordering (the modes 5–6 and 8–9). To describe qualitatively the most significant movements, the two first modes from STAT5a and p-STAT5b were used for illustration of the large displacements of the distal region of the CCD and the p-Tail (Fig 5B). These regions clearly demonstrate the greatest mobility in respect to the other domains in all studied STAT5.


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)

Comparison of the global dynamics by Normal Modes Analysis of STAT5 proteins.(A) The Cα atoms root mean square fluctuations as a function of residue number. Results for the two first modes are shown at top and bottom panels respectively, are denoted by color: STAT5a is in blue, pSTAT5a is in yellow, STAT5b is in green and p-STAT5b is in magenta. (B) First and second slowest motion modes illustrating atomic motions of STAT5a (top) and STAT5b (bottom). The STAT5 proteins displayed in cartoon representation are in light blue (STAT5a) and in dark blue (p-STAT5b). The atomic (Cα) components of each mode are drawn in red (first mode) and yellow (second mode) arrows. The length of arrows is positively correlated with motion magnitude and their orientation indicates motion direction. (C) Overlaps between the ten slowest modes of the phosphorylated and non-phosphorylated STAT5a (left) and STAT5b (right) are shown in the heatmap.
© Copyright Policy
Related In: Results  -  Collection

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

pone.0145142.g005: Comparison of the global dynamics by Normal Modes Analysis of STAT5 proteins.(A) The Cα atoms root mean square fluctuations as a function of residue number. Results for the two first modes are shown at top and bottom panels respectively, are denoted by color: STAT5a is in blue, pSTAT5a is in yellow, STAT5b is in green and p-STAT5b is in magenta. (B) First and second slowest motion modes illustrating atomic motions of STAT5a (top) and STAT5b (bottom). The STAT5 proteins displayed in cartoon representation are in light blue (STAT5a) and in dark blue (p-STAT5b). The atomic (Cα) components of each mode are drawn in red (first mode) and yellow (second mode) arrows. The length of arrows is positively correlated with motion magnitude and their orientation indicates motion direction. (C) Overlaps between the ten slowest modes of the phosphorylated and non-phosphorylated STAT5a (left) and STAT5b (right) are shown in the heatmap.
Mentions: The square fluctuations of Cα atoms calculated from the first two NMA modes show that for all studied proteins, the mostly fluctuated residues are located in the distal CCD (Fig 5A). The amplitudes of the distal CCD fluctuations, explained by the first and second modes, are higher in p-STAT5a and STAT5b, than those observed in STAT5a and p-STAT5b. Other slow motions are observed in the p-Tail and in the solvent exposed loops of the linker and SH2 domains. Similarly to CCD, the fluctuations of the p-Tail residues are increased in STAT5b and p-STAT5a. This observation correlates with the square fluctuations behavior over the MD simulations. Computed scalar products between the first ten NMA modes from each pair of proteins (phosphorylated, p-STAT5 and non-phosphorylated, STAT5) indicate a good overlap between the two ensembles (Fig 5C). Namely, the modes intrinsically accessible in STAT5 are closely maintained in p-STAT5. Nevertheless, some differences are observed: while the modes 1–3 and 6–8 are maintained with an overlap of 0.7 or above in STAT5b, in STAT5a significantly fewer global modes (1–4, 7) are conserved, along with a weaker correlation and reordering (the modes 5–6 and 8–9). To describe qualitatively the most significant movements, the two first modes from STAT5a and p-STAT5b were used for illustration of the large displacements of the distal region of the CCD and the p-Tail (Fig 5B). These regions clearly demonstrate the greatest mobility in respect to the other domains in all studied STAT5.

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