Biology subjects

Amato, M.

Publications and source records attributed to Amato, M..

4 recordsLinked to original sources

bioRxiv2024

Phospho-regulated tuning of viscoelastic properties balances centrosome growth and strength

Centrosomes are membranelles organelles containing centrioles encapsulated by pericentriolar material (PCM). PCM nucleates microtubules that help position and segregate chromosomes during mitosis, yet how PCM resists microtubule-mediated forces is poorly understood at the material level. Here, we show that PLK-1 phosphorylation of SPD-5 tunes the dynamics and material properties of the PCM scaffold in C. elegans embryos. Microrheology of reconstituted PCM condensates reveals that PLK-1 phosphorylation decreases SPD-5 dynamics and increases condensate viscoelasticity. Similarly, in embryos, phospho-mimetic SPD-5 is less dynamic than wild-type SPD-5, which itself is less dynamic than phospho-null SPD-5. PCM built with phospho-null SPD-5 is smaller than normal, but its assembly can be partially rescued by reducing microtubule-dependent forces. The same is true for PCM built with phospho-mimetic SPD-5, yet the underlying causes are distinct: under force, phospho-null SPD-5 fails to assemble, while phospho-mimetic SPD-5 forms hyper-stable foci that fail to cohere into a uniform, spherical mass. Both mutants have defects with chromosome segregation and viability. Thus, tuning of SPD-5 phosphorylation optimizes PCM material properties to achieve correct PCM size, integrity, and function. Our results demonstrate how regulated chemical modification of a scaffolding protein modulates the material properties and function of a membraneless organelle.

cell biology↗

bioRxiv2023

Recombinase Polymerase Amplification Assay for the Field Detection of Mal Secco Disease by Plenodomus tracheiphilus

In this study, we developed a new diagnostic assay based on the recombinase polymerase amplification (RPA) technology to detect Plenodomus tracheiphilus, the anamorphic fungus responsible for the destructive vascular disease of lemon named mal secco, in infected tissues of host plants. A 142 bp RPA-compatible barcode was sought within the 544 bp Internal Transcriber Spacer (ITS) fragment identified in a previous study and its P. tracheiphilus-specificity was confirmed by BLAST in the NCBI database. This was the premise to design an RPA probe (RPA_Ptrach_Probe). The specificity and inclusivity of the RPA assay were tested on gDNA isolated from tissues of C. limon, isolates of P. tracheiphilus of various origins and axenic cultures of non-target organisms, including fungal and oomycete pathogens typically associated to citrus trees, such as Alternaria spp., Colletotrichum spp., Phyllosticta spp., Penicillium spp., Phytophthora spp. With a detection threshold of 1.0 pg of gDNA the RPA assay proved to be as sensitive as the SYBR(R) Green I Real Time-PCR test included in the diagnostic protocol for P. tracheiphilus of the European and Mediterranean Plant Protection Organization. RPA assay was even more sensitive than Real Time-PCR in tests on DNA samples obtained through a rapid extraction method. In tests, on naturally infected lemon twigs, molecular approaches were comparable to each other and performed better than conventional isolation method. Overall, results of this study demonstrate the potential of RPA for rapid, easy to handle and cost effective in-field diagnosis of mal secco.

molecular biology↗

bioRxiv2023

Multivalent coiled-coil interactions enable full-scale centrosome assembly and strength

During mitotic spindle assembly, microtubules generate tensile stresses on pericentriolar material (PCM), the outermost layer of centrosomes. The molecular interactions that enable PCM to assemble rapidly and resist external forces are unknown. Here we use cross-linking mass spectrometry to identify interactions underlying supramolecular assembly of SPD-5, the main PCM scaffold protein in C. elegans. Crosslinks map primarily to alpha helices within the phospho-regulated region (PReM), a long C-terminal coiled-coil, and a series of four N-terminal coiled-coils. PLK-1 phosphorylation of SPD-5 creates new homotypic contacts, including two between PReM and the CM2-like domain, and eliminates numerous contacts in disordered linker regions, thus favoring coiled-coil-specific interactions. Mutations within these interacting regions cause PCM assembly defects that are partly rescued by eliminating microtubule-mediated forces. Thus, PCM assembly and strength are interdependent. In vitro, self-assembly of SPD-5 scales with coiled-coil content, although there is a defined hierarchy of association. We propose that multivalent interactions among coiled-coil regions of SPD-5 build the PCM scaffold and contribute sufficient strength to resist microtubule-mediated forces.

cell biology↗

bioRxiv2020

Protein hyperacylation links mitochondrial dysfunction with nuclear organization

Cellular metabolism is linked to epigenetics, but the biophysical effects of metabolism on chromatin structure and implications for gene regulation remain largely unknown. Here, using a broken tricarboxylic acid (TCA) cycle and disrupted electron transport chain (ETC) exemplified by succinate dehydrogenase subunit C (SDHC) deficiency, we investigated the effects of metabolism on chromatin architecture over multiple distance scales [nucleosomes ([~]102 bp), topologically-associated domains (TADs; [~]105 - 106 bp), and chromatin compartments (106 - 108 bp)]. Metabolically-driven hyperacylation of histones led to weakened nucleosome positioning in multiple types of chromatin, and we further demonstrate that lysine acylation directly destabilizes histone octamer-DNA interactions. Hyperacylation of cohesin subunits correlated with decreased mobility on interphase chromatin and increased TAD boundary strength, suggesting that cohesin is metabolically regulated. Erosion of chromatin compartment distinctions reveals metabolic regulation of chromatin liquid-liquid phase separation. The TCA cycle and ETC thus modulate chromatin structure over multiple distance scales.

cell biology↗