Biology subjects

Cutts, E. E.

Publications and source records attributed to Cutts, E. E..

6 recordsLinked to original sources

bioRxiv2026

Defective HIRA driven chromatin maintenance underlies age related decline in oocyte quality

The rapid fertility decline in women over 35 years of age has been attributed to decreasing oocyte quality. Aging oocytes accumulate DNA damage, chromosome segregation defects and altered epigenetic modifications. Critically, the molecular mechanisms underlying these changes remain poorly understood. Here we uncovered that in the mouse, the HIRA driven H3.3 histone replacement is attenuated during oocyte aging leading to the loss of chromatin homeostasis. The loss of HIRA function is caused by its SUMOylation resulting in the disruption of HIRA-UBN1-CABIN1 complex and its association with chromatin. We further show that preventing HIRA SUMOylation restores H3.3 incorporation and chromatin integrity in aged mouse oocytes leading to improved oocyte maturation and preimplantation development rates. Importantly, similar chromatin homeostasis defect is observed in aging human oocytes pointing towards a conserved process. Our findings provide novel insights into the molecular mechanisms underlying age-related oocyte quality decline and pave the way for clinical interventions.

developmental biology↗

bioRxiv2026

Molecular Mechanism of Condensin II auto-repression by NCAPD3 and activation by M18BP1

Human condensin II is a constitutively nuclear molecular motor that initiates chromosome organization in early mitosis. How condensin II is activated specifically in mitosis remains unknown. Here, we describe the molecular mechanism underlying condensin II auto-repression and activation. By determining multiple structural states of condensin II, we discovered that an autoinhibitory tail within the NCAPD3 subunit (NCAPD3Tail) holds the complex in a conformation that is incompatible with DNA capture. Deletion of NCAPD3Tail spontaneously activates condensin II in cells, illuminating its autoinhibitory role in vivo. We further show this translates to increased loop DNA formation by condensin II in vitro. Direct competition for the NCAPD3Tail binding site on condensin II enables the putative activator protein M18BP1 to liberate a key DNA-binding element in the NCAPH2 N-terminus, enabling DNA capture. Unexpectedly, M18BP1 not only relieves autoinhibition but also directly contributes to DNA organization by forming a positively charged loop that enhances DNA-anchoring by condensin II. Together, these findings reveal a bipartite activation mechanism wherein M18BP1 relieves autorepression, and renders condensin II biochemically competent to form stable DNA loops, ensuring highly stringent regulation of mitotic chromosome formation.

biochemistry↗

bioRxiv2025

Binding Kinetics Oppositely Regulates type II Topoisomerase Relaxation and Decatenation Activities

Type II Topoisomerases (topo II) are critical to simplify genome topology during transcription and replication. They identify topological problems and resolve them by passing a double-stranded DNA segment through a transient break in another segment. The precise mechanisms underpinning topo IIs ability to maintain a topologically simple genome are not fully understood. Here, we investigate how binding kinetics affects the resolution of two distinct forms of topological entanglement: decatenation and torsional relaxation. First, by single-molecule measurements, we quantify how monovalent cation concentration affects the dissociation rate of topo II from DNA. Second, we discover that increasing dissociation rates accelerate decatenation while slowing down relaxation catalytic activities. Finally, by using molecular dynamics simulations, we uncover that this opposite behaviour is due to a trade-off between search of target through facilitated diffusion and processivity of the enzyme in catenated versus super-coiled DNA. Thus, our findings reveal that a modulation of topo II binding kinetics can oppositely regulate its topological simplification activity, and in turn can have a significant impact in vivo.

biophysics↗

bioRxiv2024

Herpes simplex virus type 1 origin binding protein UL9 tethers and loops origin- and non-origin-DNA intra- and intermolecularly

Herpesviruses are ubiquitous human pathogens, which are the causative agent of mild to severe symptoms ranging from cold sore to nasopharyngeal carcinoma. Even though replication of the linear dsDNA genome has been studied for decades, we still lack a complete molecular understanding of its mechanism. It has been proposed, but never shown directly, that the HSV-1 origin binding protein UL9 binds two closely located binding sites within the oriS origin sequence, thereby mediating origin looping, which in turn facilitates replication initiation. Here, we used an array of single-molecule approaches to test this long-standing hypothesis directly. Surprisingly, the data show that UL9 does not loop oriS efficiently. However, we demonstrate that UL9 can form large DNA loops at non-origin sequences very efficiently, as well as tether two oriS DNA molecules intermolecularly. Contrary to the origin bending hypothesis, our findings indicate that UL9 does not loop oriS DNA, but rather may play an alternative role in replication initiation, such as tethering two separate molecules to facilitate recombination.

microbiology↗

bioRxiv2024

Molecular Mechanism of Condensin I Activation by KIF4A

During mitosis, the condensin I and II complexes compact chromatin into chromosomes. Loss of the chromokinesin, KIF4A, results in reduced condensin I chromosome association. However, the molecular mechanism behind this phenotype is unknown. Here, we show that KIF4A binds directly to condensin I HAWK subunit, NCAPG, via a conserved disordered short linear motif (SLiM) found in its C-terminal tail. KIF4A binding directly competes with two auto-inhibitory interactions in condensin I, mediated by SLiMs found in the N-terminus of NCAPH and the C-terminus of NCAPD2, which bind sites that overlap with KIF4A binding on NCAPG. Addition of the KIF4A SLiM peptide alone is sufficient to stimulate condensins ATPase and DNA loop extrusion activity. We also identify SLiMs in known yeast condensin interactors, Sgo and Lrs4, that bind yeast Ycg1, the HAWK equivalent to NCAPG. Our findings, together with previous work on condensin II and cohesin, demonstrate that SLiMs binding to HAWK subunits is a conserved mechanism of regulation in SMC complexes.

biochemistry↗

bioRxiv2020

A commercial antibody to the human condensin II subunit NCAPH2 cross-reacts with a SWI/SNF complex component

Condensin complexes compact and disentangle chromosomes in preparation for cell division. Commercially available antibodies raised against condensin subunits have been widely used to characterise their cellular interactome. Here we have assessed the specificity of a polyclonal antibody (Bethyl A302-276A) that is commonly used as a probe for NCAPH2, the kleisin subunit of condensin II, in mammalian cells. We find that, in addition to its intended target, this antibody cross-reacts with one or more components of the SWI/SNF family of chromatin remodelling complexes in an NCAPH2-independent manner. This cross-reactivity with an abundant chromatin-associated factor is likely to affect the interpretation of protein and chromatin immunoprecipitation experiments that make use of this antibody probe.

cell biology↗