Biology subjects

Esposito Verza, A.

Publications and source records attributed to Esposito Verza, A..

3 recordsLinked to original sources

bioRxiv2025

Molecular requirements for PLK1 activation by T-loop phosphorylation

Activation of PLK1, a master mitotic kinase, requires phosphorylation of its activation segment on Thr210, within a basic consensus sequence for Aurora kinases. Aurora B-dependent phosphorylation of Thr210 has been reported, but other evidence identified a strict requirement for the Aurora A partner Bora for Thr210 phosphorylation. Here, we investigate the elusive mechanistic basis for this requirement. We show that Aurora A:Bora phosphorylates Thr210 of PLK1 in vitro, while Aurora A, other Aurora A:activator complexes, and Aurora B:INCENP fail to target T210 even at high kinase/substrate ratios. A transient interaction of Bora and PLK1, identified by structural modelling and probed mutationally, is uniquely required for Thr210 phosphorylation. Dependency on Bora for Thr210 phosphorylation is eliminated after mutating Lys208, in the Aurora consensus, into arginine. This conservative mutation turns PLK1 into an excellent substrate of nearly all tested active Aurora kinases, especially Aurora B. Collectively, these results shine a new light on the specificity of the PLK1 activation mechanism.

biochemistry↗

bioRxiv2025

Molecular anatomy of PLK1 master docking motifs

The Polo-box domain (PBD) localizes Polo-like kinase 1 (PLK1) near mitotic substrates required for chromosome biorientation. Recent work on mitotic kinetochores showed PLK1 docking begins hierarchically at master docking motifs on BUB1 and CENP-U. Whether master docking motifs have common molecular features remains poorly understood. Presence on CENP-U of two neighbouring motifs generated by initial CDK1 priming and subsequent PLK1 phosphorylation led us to hypothesize PBD dimerization might be involved. Using biochemical, biophysical, and modelling approaches, we gathered strong evidence that CENP-U contains a single master docking motif. The motif is very high affinity and sufficient to form extensive interactions with the PBD, engaging multiple pockets on its surface without obvious added benefits from dimerization. Comparisons with motifs in BUB1, BUBR1, and PRC1 suggests apparent commonalities of master PLK1 docking motifs. We discuss the implications of our observations for the mechanism of PLK1 activation.

biochemistry↗

bioRxiv2024

Role of PLK1 in the epigenetic maintenance of centromeres

The centromere, a chromosome locus defined by the histone H3-like protein CENP-A, seeds the kinetochore to bind microtubules during cell division. Centromere maintenance requires CENP-A to be actively replenished by dedicated protein machinery in the early G1 cell-cycle phase, compensating for its two-fold dilution following DNA replication. Cyclin-dependent kinases (CDKs) limit CENP-A deposition to once per cell cycle and function as negative regulators outside early G1. Antithetically, Polo-like kinase 1 (PLK1) promotes CENP-A deposition in early G1, but the molecular details are still unknown. We reveal a phosphorylation network that recruits PLK1 to the deposition machinery to control a conformational switch required for licensing the CENP-A deposition reaction. Our findings solve the long-standing question of how PLK1 contributes to the epigenetic maintenance of centromeres. One-Sentence SummaryPLK1 licenses epigenetic maintenance of centromeres by regulating a conformational switch on the MIS18 protein.

cell biology↗