@article {2025,
	title = {Impact of multiple phosphorylations on the tau-R2/tubulin interface},
	journal = {Biochemistry},
	year = {2025},
	abstract = {<p>The phosphorylation of the microtubule-associated tau protein plays a key role in the regulation of its physiological function. In particular, tau hyperphosphorylation affects its binding to the tubulin surface, destabilizing the tau-microtubule interface and leading to the accumulation of fibrillar aggregates in the brain. In this work, we performed classical molecular dynamics simulations for the tau-R2/tubulin assembly with various phosphorylation states of serines 285, 289, and 293. We analyze the resulting trajectories to obtain a detailed view of the protein interface in the complex and the impact of tau phosphorylations on the stability of this assembly and on the mobility of the tubulin disordered C-terminal tails (CTTs). We show how the tubulin CTTs help maintain the tau-R2 fragment on the tubulin surface despite the destabilizing effect induced by phosphorylations. Conversely, tau phosphorylation affects the CTTs\&$\#$39; flexibility and their potential activity as MAP-recruiting hooks. Furthermore, counterion-mediated bridges between the phosphate groups and tubulin glutamates also contribute to the binding of tau-R2 on the MT. Overall, the complex dynamics of this fuzzy phosphorylated assembly shed new light on the importance of the cytoplasmic environment in neurons in the context of Alzheimer\&$\#$39;s disease.</p>
},
	author = {Marien, Jules and Pr{\'e}vost, Chantal and S Sacquin-Mora}
}
@article {2024|2167,
	title = {NP-collabs: Investigating counterion-mediated bridges in the multiply phosphorylated tau-R2 repeat},
	journal = {J. Chem. Inf. Model.},
	volume = {64},
	year = {2024},
	pages = {6570{\textendash}6582},
	abstract = {<p>Tau is an intrinsically disordered (IDP) microtubule-associated protein (MAP) that plays a key part in microtubule assembly and organization. The function of tau can be regulated by multiple phosphorylation sites. These post-translational modifications are known to decrease the binding affinity of tau for microtubules, and abnormal tau phosphorylation patterns are involved in Alzheimer\&$\#$39;s disease. Using all-atom molecular dynamics simulations, we compared the conformational landscapes explored by the tau R2 repeat domain (which comprises a strong tubulin binding site) in its native state and with multiple phosphorylations on the S285, S289, and S293 residues, with four different standard force field (FF)/water model combinations. We find that the different parameters used for the phosphate groups (which can be more or less flexible) in these FFs and the specific interactions between bulk cations and water lead to the formation of a specific type of counterion bridge, termed nP-collab (for nphosphate collaboration, with n being an integer), where counterions form stable structures binding with two or three phosphate groups simultaneously. The resulting effect of nP-collabs on the tau-R2 conformational space differs when using sodium or potassium cations and is likely to impact the peptide overall dynamics and how this MAP interacts with tubulins. We also investigated the effect of phosphoresidue spacing and ionic concentration by modeling polyalanine peptides containing two phosphoserines located one-six residues apart. Three new metrics specifically tailored for IDPs (proteic Menger curvature, local curvature, and local flexibility) were introduced, which allow us to fully characterize the impact of nP-collabs on the dynamics of disordered peptides at the residue level.</p>
},
	author = {Marien, Jules and Pr{\'e}vost, Chantal and S Sacquin-Mora}
}
