Biology subjects

Zorrilla, S.

Publications and source records attributed to Zorrilla, S..

5 recordsLinked to original sources

bioRxiv2024

Bacterial cell cycle regulator MatP forms biomolecular condensates and directly interacts with cell division protein FtsZ

An increasing number of proteins involved in bacterial cell cycle events have been recently shown to undergo phase separation. The resulting biomolecular condensates play an important role in cell cycle protein function and may be involved in development of persister cells tolerant to antibiotics. Here we report that the E. coli chromosomal Ter macrodomain organizer MatP, a division site selection protein implicated in the coordination of chromosome segregation with cell division, forms biomolecular condensates in cytomimetic systems. These condensates are favored by crowding and preferentially localize at the membrane of microfluidics droplets, a behavior probably mediated by MatP-lipid binding. Condensates are negatively regulated and partially dislodged from the membrane by DNA sequences recognized by MatP (matS), which partition into them. Unexpectedly, MatP condensation is enhanced by FtsZ, a core component of the division machinery previously described to undergo phase separation. Our biophysical analyses uncover a direct interaction between the two proteins, disrupted by matS sequences. This binding might have implications for FtsZ ring positioning at mid-cell by the Ter linkage, which comprises MatP and two other proteins that bridge the canonical MatP/FtsZ interaction. FtsZ/MatP condensates interconvert with bundles in response to GTP addition, providing additional levels of regulation. Consistent with discrete foci reported in cells, MatP biomolecular condensates may facilitate MatPs role in chromosome organization and spatiotemporal regulation of cytokinesis and DNA segregation. Moreover, sequestration of MatP in these membraneless compartments, with or without FtsZ, could promote cell entry into dormant states that are able to survive antibiotic treatments.

biochemistry↗

bioRxiv2020

Assembly of bacterial cell division protein FtsZ into dynamic biomolecular condensates

Biomolecular condensation through phase separation may be a novel mechanism to regulate bacterial processes, including cell division. Previous work revealed FtsZ, a protein essential for cytokinesis in most bacteria, and the E. coli division site selection factor SlmA form FtsZ*SlmA biomolecular condensates. The absence of condensates composed solely of FtsZ under the conditions used in that study suggested this mechanism was restricted to nucleoid occlusion or SlmA-containing bacteria. Here we report that FtsZ alone can demix into condensates in bulk and when encapsulated in synthetic cell-like systems. Condensate assembly depends on FtsZ being in the GDP-bound state and on crowding conditions that promote its oligomerization. FtsZ condensates are dynamic and gradually convert into FtsZ filaments upon GTP addition. Notably, FtsZ lacking its C-terminal disordered region, a structural element likely to favor biomolecular condensation, also forms condensates, albeit less efficiently. The inherent tendency of FtsZ to form condensates susceptible to modulation by physiological factors, including binding partners, suggests that such mechanisms may play a more general role in bacterial cell division than initially envisioned.

biochemistry↗

bioRxiv2020

Multivalent interactions between eIF4G1, Pub1 and Pab1 drive the formation of protein condensates

Yeast eIF4G1 interacts with RNA binding proteins (RBPs) like Pab1 and Pub1 affecting its function in translation initiation and stress granules formation. We present an NMR and SAXS study of the intrinsically disordered region of eIF4G1, eIF4G11-249, and its interactions with Pub1 and Pab1. The conformational ensemble of eIF4G11-249 shows an -helix within the BOX3 conserved element and a dynamic network of fuzzy {pi}-{pi} and {pi}-cation interactions involving arginine and aromatic residues. The Pab1 RRM2 domain interacts with eIF4G1 BOX3, the canonical interaction site, but also with BOX2, a conserved element of unknown function to date. In contrast, the Pub1 RRM3 domain interacts with the RNA1-1 and BOX1 regions of eIF4G1. Mixtures of Pub1, Pab1 and eIF4G1 form micrometer-size protein condensates that require the presence of the eIF4G1 BOX1 element. These homotypic interactions suggest a double key mechanism of eIF4G1 regulation, important for understanding the architecture of stress granule cores.

biophysics↗

bioRxiv2018

The bacterial DNA binding protein MatP involved in linking the nucleoid terminal domain to the divisome at midcell interacts with lipid membranes

Division ring formation at midcell is controlled by various mechanisms in Escherichia coli, one of them being the linkage between the chromosomal Ter macrodomain and the Z-ring mediated by MatP, a DNA binding protein that organizes this macrodomain and contributes to the prevention of premature chromosome segregation. Here we show that, during cell division, just before splitting the daughter cells, MatP seems to localize close to the cytoplasmic membrane, suggesting that this protein might interact with lipids. To test this hypothesis, we investigated MatP interaction with lipids in vitro. We found that MatP, when encapsulated inside microdroplets generated by microfluidics and giant vesicles, accumulates at phospholipid bilayers and monolayers matching the lipid composition in the E. coli inner membrane. MatP binding to lipids was independently confirmed using lipid coated microbeads and bio-layer interferometry assays. Interaction of MatP with the lipid membranes also occurs in the presence of the DNA sequences specifically targeted by the protein but there is no evidence of ternary membrane/protein/DNA complexes. We propose that the interaction of MatP with lipids may modulate its spatiotemporal localization and its recognition of other ligands.\n\nIMPORTANCEThe division of an E. coli cell into two daughter cells with equal genomic information and similar size requires duplication and segregation of the chromosome and subsequent scission of the envelope by a protein ring, the Z-ring. MatP is a DNA binding protein that contributes both to the positioning of the Z-ring at midcell and the temporal control of nucleoid segregation. Our integrated in vivo and in vitro analysis provides evidence that MatP can interact with lipid membranes comprising the phospholipid mixture in the E. coli inner membrane, without concomitant recruitment of the short DNA sequences specifically targeted by MatP. This observation strongly suggests that the membrane may play a role in the regulation of the function and localization of MatP, which could be relevant for the coordination of the two fundamental processes in which this protein participates, nucleoid segregation and cell division.

biochemistry↗

bioRxiv2018

Bacterial division FtsZ forms liquid condensates with nucleoid-associated Z-ring inhibitor SlmA

Macromolecular condensation resulting from biologically regulated liquid-liquid phase transitions is emerging as a mechanism to organize the intracellular space in eukaryotic systems, with broad implications in cell physiology and pathology. Here we show that FtsZ, central element of the division ring in most bacteria, forms condensates when in complex with SlmA, the protein preventing septal ring assembly nearby the chromosome in E. coli. The formation of condensates is promoted by crowding and enhanced by sequence-specific binding of SlmA to DNA. These structures are dynamic and FtsZ within them remains active for GTP-triggered fiber formation. Their location is sensitive to compartmentalization and to the presence of a membrane boundary in microfluidics-based cell mimetic systems, likely affecting their reactivity. We propose that reversible condensation may play a role in the modulation of FtsZ assembly and/or location by SlmA and, hence, in the regulation of ring stability, constituting a singular example of a prokaryotic nucleoprotein complex exhibiting this kind of phase transition.

biochemistry↗