PTP-MEG2 regulates quantal size and fusion pore opening through two distinct structural bases and substrates

Xu, Y.-f.; Sun, J.; Yu, X.; Chen, X.; Cui, M.; Yang, Z.; Liu, C.-h.; Yang, X.-z.; Wang, Y.-j.; Liu, Q.; Zhang, S.; Wang, C.; Shen, Y.-m.; Zhang, Z.-y.; Zhao, W.-d.; Wang, C.-h.; Ji, Z.-l.; Xiao, P.; Li, K.-s.

doi:10.1101/822031

bioRxiv · 10.1101/822031

PTP-MEG2 regulates quantal size and fusion pore opening through two distinct structural bases and substrates

Xu, Y.-f.·Sun, J.·Yu, X.·Chen, X.·Cui, M.·Yang, Z.·Liu, C.-h.·Yang, X.-z.·Wang, Y.-j.·Liu, Q.·Zhang, S.·Wang, C.·Shen, Y.-m.·Zhang, Z.-y.·Zhao, W.-d.·Wang, C.-h.·Ji, Z.-l.·Xiao, P.·Li, K.-s.

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Abstract

Tyrosine phosphorylation of secretion machinery proteins is a crucial regulatory mechanism for exocytosis. However, the participation of protein tyrosine phosphatases (PTPs) in different exocytosis stages has not been defined. Here we demonstrated that PTP-MEG2 controls multiple steps of catecholamine secretion. Biochemical and crystallographic analyses revealed key residues that the interactions between govern the PTP-MEG2 and NSF-pY83 site, specify PTP-MEG2 substrate selectivity and modulate the fusion of catecholamine-containing vesicles. Unexpectedly, delineation of PTP-MEG2 mutants along with the NSF binding interface revealed that PTP-MEG2 controls the fusion pore opening through non-NSF dependent mechanisms. Utilizing bioinformatics search and biochemical and electrochemical screening approaches, we discovered that PTP-MEG2 regulates the opening and extension of the fusion pore by dephosphorylating the DYNAMIN2-pY125 and MUNC18-1-pY145 site. Further structural and biochemical analysis confirmed the interaction of PTP-MEG2 with MUNC18-1-pY145 or DYNAMIN2-pY125 through a distinct structural basis compared with that of the NSF-pY83 site. Our studies extended mechanistic insights in complex exocytosis processes. HIGHLIGHTSPTP-MEG2 regulates multiple steps of exocytosis. A crystal structure of the PTP-MEG2/phosphor-NSF-pY83 segment was obtained. Functional delineation of the PTP-MEG2/NSF interface led to the discovery of new PTP-MEG2 substrates. PTP-MEG2 regulates fusion pore opening and extension through the DYNAMIN2-pY125 site and MUNC18-1 pY145 site. The distinct structural basis of the recognition of substrates by PTP-MEG2 allows selective inhibitor design.

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Xu, Y.-f., Sun, J., Yu, X., Chen, X., Cui, M., Yang, Z., Liu, C.-h., Yang, X.-z., Wang, Y.-j., Liu, Q., Zhang, S., Wang, C., Shen, Y.-m., Zhang, Z.-y., Zhao, W.-d., Wang, C.-h., Ji, Z.-l., Xiao, P., Li, K.-s.. 2019-10-29. PTP-MEG2 regulates quantal size and fusion pore opening through two distinct structural bases and substrates. https://doi.org/10.1101/822031

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