Abstract
Protein tyrosine phosphatases (PTPs) originating from eukaryotes or bacteria have been under intensive structural and biochemical investigation, whereas archaeal PTP proteins have not been investigated extensively; therefore, they are poorly understood. Here, we present the crystal structures of Tk-PTP derived from the hyperthermophilic archaeon Thermococcus kodakaraensis KOD1, in both the active and inactive forms. Tk-PTP adopts a common dual-specificity phosphatase (DUSP) fold, but it undergoes an atypical temperature-dependent conformational change in its P-loop and α4−α5 loop regions, switching between the inactive and active forms. Through comprehensive analyses of Tk-PTP, including additional structural determination of the G95A mutant form, enzymatic activity assays, and structural comparison with the other archaeal PTP, it was revealed that the presence of the GG motif in the P-loop is necessary but not sufficient for the structural flexibility of Tk-PTP. It was also proven that Tk-PTP contains dual general acid/base residues unlike most of the other DUSP proteins, and that both the residues are critical in its phosphatase activity. This work provides the basis for expanding our understanding of the previously uncharacterized PTP proteins from archaea, the third domain of living organisms.
Highlights
Protein tyrosine phosphatases (PTPs) constitute a protein family, which mediates one of the common and significant post-translational modifications called protein tyrosine phosphorylation by coordinating with protein tyrosine kinases [1,2,3,4]
We found that Tk-PTP(form I) was well aligned to DUSP23b and DUSP23a, with a root mean square deviation (RMSD) of 1.52 Å over 142 aligned residues and 1.54 Å over 137 aligned residues, respectively (Fig 1B)
We presented in-depth structural and biochemical analyses based on the newly determined crystal structures of three forms of Tk-PTP, the PTP protein from T. kodakaraensis KOD1
Summary
Protein tyrosine phosphatases (PTPs) constitute a protein family, which mediates one of the common and significant post-translational modifications called protein tyrosine phosphorylation by coordinating with protein tyrosine kinases [1,2,3,4]. PTP proteins can be classified into several categories based on folding and domain composition. Crystal structures of three forms of Tk-PTP to SJK. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript
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