Parvulin 17-catalyzed Tubulin Polymerization Is Regulated by Calmodulin in a Calcium-dependent Manner

Abstract

Recently we have shown that the peptidyl-prolyl cis/trans isomerase parvulin 17 (Par17) interacts with tubulin in a GTP-dependent manner, thereby promoting the formation of microtubules. Microtubule assembly is regulated by Ca(2+)-loaded calmodulin (Ca(2+)/CaM) both in the intact cell and under in vitro conditions via direct interaction with microtubule-associated proteins. Here we provide the first evidence that Ca(2+)/CaM interacts also with Par17 in a physiologically relevant way, thus preventing Par17-promoted microtubule assembly. In contrast, parvulin 14 (Par14), which lacks only the first 25 N-terminal residues of the Par17 sequence, does not interact with Ca(2+)/CaM, indicating that this interaction is exclusive for Par17. Pulldown experiments and chemical shift perturbation analysis with (15)N-labeled Par17 furthermore confirmed that calmodulin (CaM) interacts in a Ca(2+)-dependent manner with the Par17 N terminus. The reverse experiment with (15)N-labeled Ca(2+)/CaM demonstrated that the N-terminal Par17 segment binds to both CaM lobes simultaneously, indicating that Ca(2+)/CaM undergoes a conformational change to form a binding channel between its two lobes, apparently similar to the structure of the CaM-smMLCK(796-815) complex. In vitro tubulin polymerization assays furthermore showed that Ca(2+)/CaM completely suppresses Par17-promoted microtubule assembly. The results imply that Ca(2+)/CaM binding to the N-terminal segment of Par17 causes steric hindrance of the Par17 active site, thus interfering with the Par17/tubulin interaction. This Ca(2+)/CaM-mediated control of Par17-assisted microtubule assembly may provide a mechanism that couples Ca(2+) signaling with microtubule function.

Pin1 Is Regulated by CaMKII Activation in Glutamate-Induced Retinal Neuronal Regulated Necrosis

“…In addition, peptidyl-prolyl cis / trans isomerase parvulin 17 (Par17) is another subtype of the PPIases family. It has been reported that Par17 is able to interact with CaM at the 25-residue elongation of the Par17 N-terminus (Burgardt et al, 2015). Whether Pin1 could directly interact with CaM, the up-regulator of CaMKII, also needs to be further investigated.…”

Structural Analysis of the 42 kDa Parvulin of Trypanosoma brucei

“…Noticeably, all (but cdc2) kinases, which, according to the Netphos prediction, execute the post-translational modifications of the Tb Par42 linker region (Figure 10), are involved in Wnt-signaling [66,67], and are active in cytoskeleton organization, mitotic regulation, neuronal patterning, and cell fate decision. Many of these events have been demonstrated to be influenced by parvulins Pin1 and Par14/17 [9,68,69] in human cells. The IDR character of Tb Par42 and the involvement of relatives from other organisms in protein assemblies seems to be supportive for the recruitment platform hypothesis of this protein.…”

Begomoviral Movement Protein Effects in Human and Plant Cells: Towards New Potential Interaction Partners

“…HsPin4 also promotes MT assembly by its peptidyl-prolyl cis / trans isomerase activity [ 61 ]. Interestingly, HsPin4 co-localized in the nucleolus during interphase, on the spindle apparatus during mitosis [ 62 ], and was up-regulated during the S and G2/M phases in synchronized human foreskin fibroblast cells [ 63 ]. This is consistent with data obtained from a transcriptomic analysis that showed AtPin4 upregulation during CaLCuV geminivirus infection [ 64 ].…”