An integrative approach unveils a distal encounter site for rPTPε and phospho-Src complex formation

Protein tyrosine phosphatase: phospho-protein complex structure determination, which requires to understand how specificity is achieved at the protein level remains a significant challenge for protein crystallography and cryoEM due to the transient nature of binding interactions. Using rPTP{varepsilon}D1 and phospho-SrcKD as a model system, we established an integrative workflow involving protein crystallography, SAXS and pTyr-tailored MD simulations to reveal the complex formed between rPTP{varepsilon}D1 and phospho-SrcKD, revealing transient protein-protein interactions distal to the active site. To support our finding, we determined the associate rate between rPTP{varepsilon}D1 and phospho-SrcKD and showed that a single mutation on rPTP{varepsilon}D1 disrupts this transient interaction, resulting in the reduction of association rate and activity. Our simulations suggest that rPTP{varepsilon}D1 employs a binding mechanism involving conformational change prior to the engagement of cSrcKD. This integrative approach is applicable to other PTP: phospho-protein complex determination and is a general approach for elucidating transient protein surface interactions.