Biology subjects

Corrao, C.

Publications and source records attributed to Corrao, C..

4 recordsLinked to original sources

bioRxiv2025

Hydra domain drives SNF2L multimerization and marks ISWI diversification in parasites

ISWI chromatin remodelers are conserved regulators of nucleosome positioning and chromatin accessibility across eukaryotes, yet their evolutionary diversification is poorly understood. In the apicomplexan parasite Toxoplasma gondii, we identify Hydra, a previously unrecognized globular domain embedded within TgSNF2L, one of two ISWI paralogues. Hydra is structurally unique, lacking homology to any known protein fold, and represents a lineage-specific insertion in an otherwise structurally conserved protein family. Biochemical analyses reveal that the isolated Hydra domain self-assembles into stable oligomers, undergoing reversible equilibrium with its monomeric form. Cryo-electron microscopy analysis reveals discrete globular assemblies, though little consistency could be obtained, suggesting a highly dynamic complex. Deletion of Hydra from full-length TgSNF2L disrupts its intrinsic ability to form higher order oligomers in solution, yielding predominantly monomeric and dimeric species. Functionally, the Hydra-driven multimerization of TgSNF2L modulates its availability for chromatin engagement in response to cell-cycle cues. Hydra thus represents the first reported structural innovation within the ISWI family.

molecular biology↗

bioRxiv2023

In vitro production of cat-restricted Toxoplasma pre-sexual stages by epigenetic reprogramming

Summary paragraphSexual reproduction of Toxoplasma gondii, which is restricted to the small intestine of felids, is sparsely documented, due to ethical concerns surrounding the use of cats as model organisms. Chromatin modifiers dictate the developmental fate of the parasite during its multistage life cycle, but their targeting to stage-specific cistromes is poorly described1. In this study, we found that transcription factors AP2XII-1 and AP2XI-2, expressed in tachyzoite stage that causes acute toxoplasmosis, can silence genes necessary for merozoites, a developmental stage critical for sexual commitment and transmission to the next host, including humans. Their conditional and simultaneous depletion leads to a drastic change in the transcriptional program, promoting a complete transition from tachyzoites to merozoites. Pre-gametes produced in vitro under these conditions are characterized by specific protein markers and undergo typical asexual endopolygenic division cycles. In tachyzoites, AP2XII-1 and AP2XI-2 bind DNA as heterodimers at merozoite promoters and recruit the epigenitors MORC and HDAC31, which in turn restrict the accessibility of chromatin to the transcriptional machinery. Thus, the commitment to merogony stems from a profound epigenetic rewiring orchestrated by AP2XII-1 and AP2XI-2. This effective in vitro culture of merozoites paves the way to explore Toxoplasma sexual reproduction without the need to infect kittens and has potential for the development of therapeutics to block parasite transmission.

microbiology↗

bioRxiv2021

Impaired α-tubulin re-tyrosination leads to synaptic dysfunction and is a feature of Alzheimer's disease

In neurons, dynamic microtubules play regulatory roles in neurotransmission and synaptic plasticity. While stable microtubules contain detyrosinated tubulin, dynamic microtubules are composed of tyrosinated tubulin, suggesting that the tubulin tyrosination/detyrosination (Tyr/deTyr) cycle modulates microtubule dynamics and synaptic function. In the Tyr/deTyr cycle, the C-terminal tyrosine of -tubulin is re-added by tubulin-tyrosine-ligase (TTL). Here we show that TTL+/- mice exhibit decreased tyrosinated microtubules, synaptic plasticity and memory deficits, and that reduced TTL expression is a feature of sporadic and familial Alzheimers disease (AD), with human APPV717I neurons having less dynamic microtubules. We find that spines visited by dynamic microtubules are more resistant to Amyloid{beta}1-42 and that TTL, by promoting microtubule entry into spines, prevents A{beta}1-42-induced spine pruning. Our results demonstrate that the Tyr/deTyr cycle regulates synaptic plasticity, is protective against spine injury, and that tubulin re-tyrosination is lost in AD, providing evidence that a defective Tyr/deTyr cycle may contribute to neurodegeneration.

neuroscience↗

bioRxiv2021

A plant-like mechanism coupling m6A reading to polyadenylation safeguards transcriptome integrity and developmental genes partitioning in Toxoplasma

Correct 3end processing of mRNAs is regarded as one of the regulatory cornerstones of gene expression. In a parasite that must answer to the high regulatory requirements of its multi-host life style, there is a great need to adopt additional means to partition the distinct transcriptional signatures of the closely and tandemly-arranged stage specific genes. In this study, we report on our findings in T. gondii of an m6A-dependent 3end polyadenylation serving as a transcriptional barrier at these loci. We identify the core polyadenylation complex within T. gondii and establish CPSF4 as a reader for m6A-modified mRNAs, via a YTH domain within its C-terminus, a feature which is shared with plants. We bring evidence of the specificity of this interaction both biochemically, and by determining the crystal structure at high resolution of the T. gondii CPSF4-YTH in complex with an m6A modified RNA. We show that the loss of m6A, both at the level of its deposition or its recognition was associated with an increase in aberrantly elongated chimeric mRNAs emanating from impaired transcriptional termination, a phenotype previously noticed in the plant model Arabidopsis thaliana. We bring Nanopore direct RNA sequencing-based evidence of the occurrence of transcriptional read-through breaching into downstream repressed stage-specific genes, in the absence of either CPSF4 or the m6A RNA methylase components in both T. gondii and A. thaliana. Taken together, our results shed light on an essential regulatory mechanism coupling the pathways of m6A metabolism directly to the cleavage and polyadenylation processes, one that interestingly seem to serve, in both T. gondii and A. thaliana, as a guardian against aberrant transcriptional read-throughs. HighlightsO_LIm6A is recognized in apicomplexan and plants by CPSF4, a member of the cleavage and polyadenylation complex machinery. C_LIO_LIThe structural insight behind the specificity of the binding of m6A by the CPSF4 YTH subunit are solved by high resolution crystal structures. C_LIO_LIThe m6A-driven 3end polyadenylation pathway protects transcriptome integrity by restricting transcriptional read-throughs and RNA chimera formation in apicomplexan parasites and plants. C_LI

microbiology↗