Role of Phosphorylation in Determining the Backbone Dynamics of the Serine/Threonine-Proline Motif and Pin1 Substrate Recognition

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• 作者：Mike Schutkowski ; Anne Bernhardt ; Xiao Zhen Zhou ; Minhui Shen ; Ulf Reimer ; Jens-Ullrich Rahfeld ; Kun Ping Lu ; and Gunter Fischer
• 刊名：Biochemistry
• 出版年：1998
• 出版时间：April 21, 1998
• 年：1998
• 卷：37
• 期：16
• 页码：5566 - 5575
• 全文大小：135K
• 年卷期：v.37,no.16(April 21, 1998)
• ISSN：1520-4995

文摘

Proline residues provide a backbone switch in a polypeptide chain,which is controlled by thecis/trans isomerization about the peptidyl-prolyl bond.Phosphorylation of serine- and threonine-prolinemotifs has been shown to be a critical regulatory event for manyproteins. The biological significance ofthese motifs has been further highlighted by the discovery of a noveland essential peptidyl-prolyl cis/trans isomerase Pin1. Pin1 is required for progression throughmitosis via catalyzing the isomerizationof phosphorylated Ser/Thr-Pro motifs specifically present inmitosis-specific phosphoproteins. However,little is known whether the phosphorylation regulates theconformational switch of the Ser/Thr-Pro bonds.Here, we report the synthesis and conformational characterizationof a series of peptides that contain thephosphorylated or nonphosphorylated Ser/Thr-Pro motifs.Phosphorylation affected the rate of the cis totrans isomerization of the Thr/Ser-Pro bonds. As determined by aprotease-coupled assay, the isomerizationrate of phosphorylated Thr-Pro bond was found to be 8-fold slower thanthat of the nonphosphorylatedanalogue. Furthermore, studies of the pH dependence of theisomerization of the phosphopeptides revealthat both cis content and the rate constant of prolyl cis to transisomerization are lower for the dianionicstate of the phosphothreonine-containing peptides. These effectsof phosphorylation are specific forphosphorylated Ser/Thr since neither phosphorylated Tyr nor glutamicacid was able to affect the prolylisomerization. Finally, our experiments provide evidence thateffective catalysis of cis/trans isomerizationof phosphorylated Ser/Thr-Pro bonds by Pin1 is specific to thedianionic form of the substrate. Thus, ourresults demonstrate that protein phosphorylation specifically regulatesthe backbone dynamics of the Ser/Thr-Pro motifs and that Pin1 specifically isomerizes the certainconformation of the phosphorylated Ser/Thr-Pro motifs.