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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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Structure of the STAT proteins.(A) STATs structure is composed of a N-terminal domain (N-term), a Coiled-Coil domain (CCD), a DNA Binding domain (DBD), a Linker domain (LD), a SRC homology 2 domain (SH2), a Phosphotyrosyl Tail (p-Tail), and a C-terminus named the Trans-Activation Domain (TAD); (B) The crystallographic or NMR data (Protein Data Bank, PDB) characterized a structure of STAT1 (1BF5 [12], 1YVL [13] and 2KA6 [14]), STAT2 (2KA4 [14]), STAT3 (1BG1 [15], 3CWG [16] and 4E68 [10]), STAT4 (1BGF [17]), STAT5a (1Y1U [18]) and STAT6 (1OJ5 [19]). Different STATs domains are distinguished by color: N-terminal is in orange, CCD is in blue, DBD is in red, LD is in green, SH2 is in yellow, p-Tail is in grey and TAD is in magenta.
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pone.0145142.g001: Structure of the STAT proteins.(A) STATs structure is composed of a N-terminal domain (N-term), a Coiled-Coil domain (CCD), a DNA Binding domain (DBD), a Linker domain (LD), a SRC homology 2 domain (SH2), a Phosphotyrosyl Tail (p-Tail), and a C-terminus named the Trans-Activation Domain (TAD); (B) The crystallographic or NMR data (Protein Data Bank, PDB) characterized a structure of STAT1 (1BF5 [12], 1YVL [13] and 2KA6 [14]), STAT2 (2KA4 [14]), STAT3 (1BG1 [15], 3CWG [16] and 4E68 [10]), STAT4 (1BGF [17]), STAT5a (1Y1U [18]) and STAT6 (1OJ5 [19]). Different STATs domains are distinguished by color: N-terminal is in orange, CCD is in blue, DBD is in red, LD is in green, SH2 is in yellow, p-Tail is in grey and TAD is in magenta.

Mentions: STATs genes encode for sequences of comparable lengths (from 750 to 850 amino acids) characterized by a good similarity (from 52 to > 95%) for the human full-length sequences [6]. STATs proteins consist of N-terminal domain (N-term), Core Fragment (CF) composed of a Coiled-Coil domain (CCD), DNA Binding domain (DBD), Linker domain (LD), SRC homology 2 domain (SH2), as well as a phosphotyrosyl Tail (p-Tail) and a C-terminus called the Trans-Activation Domain (TAD) (Fig 1A). Comparison of the structural architecture of STATs proteins indicates a conservation of the overall domains organization and their functional role within the family. In particular, the N-terminal domain mediates tetrameric arrangement of STAT dimers bound to adjacent DNA sites [7], the coiled-coil domain is involved in nuclear import/export [8], the DBD controls the specificity of the STAT-DNA recognition, the adjacent linker domain ensures the appropriate structure of the DNA-binding motif and regulates nuclear export in resting cells, the SH2 domain triggers dimer formation and acts either as a phosphorylation-dependent switch to control reciprocal recognition of the STAT monomers [9] or may also regulate transcription through organization of unphosphorylated STAT dimers [10], the phosphotyrosyl tail bears the tyrosine phosphorylated by upstream activator(s) to promote parallel dimerization, and the C-terminal domain contributes to the recruiting of transcription proteins through specific phosphorylated or not serine residues [11]. However, subtle sequence differences in Core Fragment as well as drastic divergence in the C-term between STAT5a and STAT5b mediate their distinct physiological actions [1,4].


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)

Structure of the STAT proteins.(A) STATs structure is composed of a N-terminal domain (N-term), a Coiled-Coil domain (CCD), a DNA Binding domain (DBD), a Linker domain (LD), a SRC homology 2 domain (SH2), a Phosphotyrosyl Tail (p-Tail), and a C-terminus named the Trans-Activation Domain (TAD); (B) The crystallographic or NMR data (Protein Data Bank, PDB) characterized a structure of STAT1 (1BF5 [12], 1YVL [13] and 2KA6 [14]), STAT2 (2KA4 [14]), STAT3 (1BG1 [15], 3CWG [16] and 4E68 [10]), STAT4 (1BGF [17]), STAT5a (1Y1U [18]) and STAT6 (1OJ5 [19]). Different STATs domains are distinguished by color: N-terminal is in orange, CCD is in blue, DBD is in red, LD is in green, SH2 is in yellow, p-Tail is in grey and TAD is in magenta.
© Copyright Policy
Related In: Results  -  Collection

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

pone.0145142.g001: Structure of the STAT proteins.(A) STATs structure is composed of a N-terminal domain (N-term), a Coiled-Coil domain (CCD), a DNA Binding domain (DBD), a Linker domain (LD), a SRC homology 2 domain (SH2), a Phosphotyrosyl Tail (p-Tail), and a C-terminus named the Trans-Activation Domain (TAD); (B) The crystallographic or NMR data (Protein Data Bank, PDB) characterized a structure of STAT1 (1BF5 [12], 1YVL [13] and 2KA6 [14]), STAT2 (2KA4 [14]), STAT3 (1BG1 [15], 3CWG [16] and 4E68 [10]), STAT4 (1BGF [17]), STAT5a (1Y1U [18]) and STAT6 (1OJ5 [19]). Different STATs domains are distinguished by color: N-terminal is in orange, CCD is in blue, DBD is in red, LD is in green, SH2 is in yellow, p-Tail is in grey and TAD is in magenta.
Mentions: STATs genes encode for sequences of comparable lengths (from 750 to 850 amino acids) characterized by a good similarity (from 52 to > 95%) for the human full-length sequences [6]. STATs proteins consist of N-terminal domain (N-term), Core Fragment (CF) composed of a Coiled-Coil domain (CCD), DNA Binding domain (DBD), Linker domain (LD), SRC homology 2 domain (SH2), as well as a phosphotyrosyl Tail (p-Tail) and a C-terminus called the Trans-Activation Domain (TAD) (Fig 1A). Comparison of the structural architecture of STATs proteins indicates a conservation of the overall domains organization and their functional role within the family. In particular, the N-terminal domain mediates tetrameric arrangement of STAT dimers bound to adjacent DNA sites [7], the coiled-coil domain is involved in nuclear import/export [8], the DBD controls the specificity of the STAT-DNA recognition, the adjacent linker domain ensures the appropriate structure of the DNA-binding motif and regulates nuclear export in resting cells, the SH2 domain triggers dimer formation and acts either as a phosphorylation-dependent switch to control reciprocal recognition of the STAT monomers [9] or may also regulate transcription through organization of unphosphorylated STAT dimers [10], the phosphotyrosyl tail bears the tyrosine phosphorylated by upstream activator(s) to promote parallel dimerization, and the C-terminal domain contributes to the recruiting of transcription proteins through specific phosphorylated or not serine residues [11]. However, subtle sequence differences in Core Fragment as well as drastic divergence in the C-term between STAT5a and STAT5b mediate their distinct physiological actions [1,4].

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