Biology subjects

Perez-Bertoldi, J. M.

Publications and source records attributed to Perez-Bertoldi, J. M..

3 recordsLinked to original sources

bioRxiv2026

Coupling of tubulin acetylation to microtubule stabilization through molecular mimicry

Microtubules support diverse cellular functions through regulation by microtubule-associated proteins and tubulin post-translational modification, yet how these two layers are mechanistically integrated remains unclear. -tubulin acetylation marks mechanically resilient microtubules, and its incorporation in defined microtubule sub-populations is not well understood. Here, we identify MTCL1 as a molecular link between microtubule stabilization and post-translational modification installation. We find that MTCL1 stabilizes microtubules and alters the luminal surface when copolymerized with tubulin, remodeling -tubulin and enhancing TAT-mediated tubulin acetylation through molecular mimicry. This effect depends on assembly history and is not observed in pre-assembled microtubules. Targeted deletion of MTCL1 in zebrafish impacts axonal organization, leading to motor defects and increased seizure susceptibility. These findings establish MTCL1 as a licensing factor that couples microtubule stabilization with acetylation to regulate neuronal function.

biophysics↗

bioRxiv2024

Molecular interplay between HURP and Kif18A in mitotic spindle regulation

During mitosis, microtubule dynamics are regulated to ensure proper alignment and segregation of chromosomes. The dynamics of kinetochore-attached microtubules are regulated by hepatoma-upregulated protein (HURP) and the mitotic kinesin-8 Kif18A, but the underlying mechanism remains elusive. Using single-molecule imaging in vitro, we demonstrate that Kif18A motility is regulated by HURP. While sparse decoration of HURP activates the motor, higher concentrations hinder processive motility. To shed light on this behavior, we determined the binding mode of HURP to microtubules using Cryo-EM. The structure reveals that one HURP motif spans laterally across {beta}-tubulin, while a second motif binds between adjacent protofilaments. HURP partially overlaps with the microtubule-binding site of the Kif18A motor domain, indicating that excess HURP inhibits Kif18A motility by steric exclusion. We also observed that HURP and Kif18A function together to suppress dynamics of the microtubule plus-end, providing a mechanistic basis for how they collectively serve in spindle length control.

biophysics↗

bioRxiv2020

The cryo-electron microscopy structure of the human CDK-activating kinase

The human CDK-activating kinase (CAK), a complex composed of cyclin dependent kinase (CDK) 7, cyclin H, and MAT1, is a critical regulator of transcription initiation and the cell cycle. It acts by phosphorylating the C-terminal heptapeptide repeat domain of the RNA polymerase II subunit Rpb1, which is an important regulatory event in transcription initiation by Pol II, and it phosphorylates the regulatory T-loop of CDKs that control cell-cycle progression. Here, we have determined the three-dimensional structure of the catalytic module of human CAK, revealing the structural basis of its assembly and providing insight into CDK7 activation in this context. The unique third component of the complex, MAT1, substantially extends the interaction interface between CDK7 and cyclin H, explaining its role as a CAK assembly factor, and it forms interactions with the CDK7 T-loop, which may contribute to enhancing CAK activity. We have also determined the structure of the CAK in complex with the covalently bound inhibitor THZ1 in order to provide insight into the binding of inhibitors at the CDK7 active site and aid in the rational design of therapeutic compounds. SignificanceControl of gene expression and the cell cycle is critical for appropriate cell growth and timely cell division. Failure of the mechanisms regulating these processes can result in proliferative diseases. A molecular complex termed the CDK activating kinase (CAK) impinges on both of these regulatory networks in human cells and is thus a possible drug target for treatment of cancer. Here, we use cryo-electron microscopy to describe the detailed molecular structure of the human CAK, revealing its architecture and the interactions between its regulatory elements. Additionally, we have obtained the structure of the CAK in complex with a small-molecule inhibitor.

biochemistry↗