Biology subjects

Perez-Borrajero, C.

Publications and source records attributed to Perez-Borrajero, C..

3 recordsLinked to original sources

bioRxiv2025

Molecular basis of ParA ATPase activation by the CTPase ParB during bacterial chromosome segregation

DNA segregation by bacterial ParABS systems is mediated by transient tethering interactions between nucleoid-bound dimers of the ATPase ParA and centromere (parS)-associated complexes of the clamp-forming CTPase ParB. The lifetime of these interactions is limited by the ParB-dependent activation of ParA ATPase activity. Here, we elucidate the functional interplay between ParA and ParB in the model bacterium Myxococcus xanthus. We demonstrate that the N-terminal ParA-binding motif of ParB associates with a conserved bipartite binding pocket at the ParA dimer interface, in a manner dependent on ParB clamp closure. Moreover, we show that ParB and non-specific DNA interact cooperatively with ParA and synergistically induce structural changes at its Walker A and Walker B motifs that correlate with the activation of ParA ATPase activity. These results advance our understanding of the mechanism underlying DNA transport by the ParABS system and may help to unravel the mode of action of related cargo-positioning systems.

microbiology↗

bioRxiv2025

Molecular mechanisms of recruitment, function and regulation of UPF1 in histone mRNA decay

Animal replication-dependent histone mRNAs end in a conserved stem loop (SL) instead of the canonical poly(A) tail present in all other eukaryotic mRNAs. Degradation of the histone SL at the end of the S-phase is initiated by the stem-loop binding protein SLBP and its interplay with the RNA helicase UPF1 and the exoribonuclease 3hExo. We report direct interactions between SLBP and UPF1 and show that the unstructured SLBP N-terminus wraps around the UPF1 helicase core, contacting it at multiple sites. Although binding of SLBP to UPF1 impedes unwinding activity, it is critical for efficient histone mRNA decay in cells, as unwinding of the SL facilitates degradation by 3hExo. Here we show that the UPF1-activator, UPF2, binds 3hExo, and that UPF2-mediated activation of UPF1 overrides the inhibitory effect of SLBP. Our results highlight the intricate network of UPF1-centric protein-protein and protein/RNA interactions that fine-tunes its unwinding activity and orchestrates timely and efficient degradation of histone mRNA.

biochemistry↗

bioRxiv2021

Structural basis of PETISCO complex assembly during piRNA biogenesis in C. elegans

Piwi-interacting RNAs (piRNAs) constitute a class of small RNAs that bind PIWI proteins and are essential to repress transposable elements in the animal germline, thereby promoting genome stability and maintaining fertility. C. elegans piRNAs (21U RNAs) are transcribed individually from minigenes as precursors that require 5 and 3 processing. This process depends on the PETISCO complex, consisting of four proteins: IFE-3, TOFU-6, PID-3, and ERH-2. We employ biochemical and structural biology approaches to characterize the PETISCO architecture and its interaction with RNA, together with its effector proteins TOST-1 and PID-1. These two proteins define different PETISCO functions: PID-1 governs 21U processing whereas TOST-1 links PETISCO to an unknown process essential for early embryogenesis. Here, we show that PETISCO forms an octameric assembly with each subunit present in two copies. Determination of structures of the TOFU-6/PID-3 and PID-3/ERH-2 subcomplexes, supported by in vivo studies of subunit interaction mutants, allows us to propose a model for the formation of the TOFU-6/PID-3/ERH-2 core complex, and its functionality in germ cells and early embryos. Using NMR spectroscopy, we demonstrate that TOST-1 and PID-1 bind to a common surface on ERH-2, located opposite its PID-3 binding site, explaining how PETISCO can mediate different cellular roles.

biochemistry↗