1. Key Laboratory Experimental Teratology of the Ministry of Education and Department of Biochemistry and Molecular Biology, Shandong University, School of Medicine, , Jinan, Shandong, China;2. Shandong Provincial School Key laboratory for Protein Science of Chronic Degenerative Diseases, , Jinan, Shandong, China;3. Provincial Hospital affiliated to Shandong University, , Jinan, Shandong, China;4. Weifang Medical University, , Weifang, Shandong, China;5. Department of Physiology, Shandong University, School of Medicine, , Jinan, Shandong, China;6. Qilu Hospital, Shandong University, , Jinan, Shandong, China;7. School of Pharmaceutical Sciences, Shandong University, , Jinan, Shandong, China;8. Weihai campus, Shandong University, , Weihai, Shandong, China;9. Department of Medicine, Duke University Medical Center, , Durham, NC, USA;10. Drug Discovery Center, Key Laboratory of Chemical Genomics, Peking University Shenzhen Graduate School, , Shenzhen, China;11. Vascular Biology Center, Department of Cellular Biology and Anatomy Medical College of Georgia, Georgia Regents University, , Augusta, Georgia, USA;12. School of Life Sciences, Shandong University, , Jinan, Shandong, China
Abstract:
Striatal‐enriched tyrosine phosphatase (STEP) is an important regulator of neuronal synaptic plasticity, and its abnormal level or activity contributes to cognitive disorders. One crucial downstream effector and direct substrate of STEP is extracellular signal‐regulated protein kinase (ERK), which has important functions in spine stabilisation and action potential transmission. The inhibition of STEP activity toward phospho‐ERK has the potential to treat neuronal diseases, but the detailed mechanism underlying the dephosphorylation of phospho‐ERK by STEP is not known. Therefore, we examined STEP activity toward para‐nitrophenyl phosphate, phospho‐tyrosine‐containing peptides, and the full‐length phospho‐ERK protein using STEP mutants with different structural features. STEP was found to be a highly efficient ERK tyrosine phosphatase that required both its N‐terminal regulatory region and key residues in its active site. Specifically, both kinase interaction motif (KIM) and kinase‐specific sequence of STEP were required for ERK interaction. In addition to the N‐terminal kinase‐specific sequence region, S245, hydrophobic residues L249/L251, and basic residues R242/R243 located in the KIM region were important in controlling STEP activity toward phospho‐ERK. Further kinetic experiments revealed subtle structural differences between STEP and HePTP that affected the interactions of their KIMs with ERK. Moreover, STEP recognised specific positions of a phospho‐ERK peptide sequence through its active site, and the contact of STEP F311 with phospho‐ERK V205 and T207 were crucial interactions. Taken together, our results not only provide the information for interactions between ERK and STEP, but will also help in the development of specific strategies to target STEP‐ERK recognition, which could serve as a potential therapy for neurological disorders.
