Publications by authors named "Chatzi K"

(1) Background: The study aimed to construct a clinically valuable closet-set WRS test with a picture identification task for young Greek-speaking children. (2) Methods: The test material was meticulously designed based on specific criteria. To determine which parts of speech are used more frequently by preschool children, a spontaneous speech sample (250 words per child) was acquired from three hundred children aged 3 to 6 years (M = 4.

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Article Synopsis
  • Protein machines, like the Sec translocase, use conformational motions to transport a wide range of non-folded preproteins across bacterial membranes.
  • The ATPase component, SecA, has a dynamic preprotein clamp that works with an ATP motor, which is regulated by ATP and ADP to achieve efficient translocation.
  • The process involves preproteins interacting with these dynamics, where signal peptides aid in clamp closing and mature domains help release ADP, ultimately leading to successful translocation of the proteins.
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Article Synopsis
  • HepG2/C3A cells can be effectively used to create a 3D liver model that accurately predicts human responses to genetic damage during drug testing.
  • The study shows that these 3D spheroids not only grow uniformly but also exhibit increased activity in key genes related to liver function and metabolism when exposed to specific genotoxic substances.
  • The 3D spheroids demonstrated a higher sensitivity to DNA damage from certain compounds compared to traditional 2D cultures, suggesting their potential to improve early drug development processes.
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The cytoplasmic ATPase SecA and the membrane-embedded SecYEG channel assemble to form the Sec translocase. How this interaction primes and catalytically activates the translocase remains unclear. We show that priming exploits a nexus of intrinsic dynamics in SecA.

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Bacterial cells growing in steady state maintain a 1:1:1 relationship between an appropriate mass increase, a round of DNA replication plus sister chromosome segregation, and cell division. This is accomplished without the cell cycle engine found in eukaryotic cells. We propose here a formal logic, and an accompanying mechanism, for how such coordination could be provided in .

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Secretory preproteins carry signal peptides fused amino-terminally to mature domains. They are post-translationally targeted to cross the plasma membrane in non-folded states with the help of translocases, and fold only at their final destinations. The mechanism of this process of postponed folding is unknown, but is generally attributed to signal peptides and chaperones.

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Most bacterial secretory proteins destined beyond the plasma membrane are secreted post-translationally by the Sec translocase. In the first step of translocation, preproteins are targeted for binding to their 2-site receptor SecA, the peripheral ATPase subunit of the translocase. We now reveal that secretory preproteins use a dual-key mechanism to bridge the signal peptide and mature domain receptor sites and cooperatively enhance their affinities.

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More than a third of the cellular proteome is non-cytoplasmic. Most secretory proteins use the Sec system for export and are targeted to membranes using signal peptides and mature domains. To specifically analyze bacterial mature domain features, we developed MatureP, a classifier that predicts secretory sequences through features exclusively computed from their mature domains.

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Secretory proteins are only temporary cytoplasmic residents. They are typically synthesized as proteins, carrying signal peptides N-terminally fused to their mature domains. In bacteria secretion largely occurs posttranslationally through the membrane-embedded SecA-SecYEG translocase.

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More than 30 years of research have revealed that the dynamic nanomotor SecA is a central player in bacterial protein secretion. SecA associates with the SecYEG channel and transports polypeptides post-translationally to the trans side of the cytoplasmic membrane. It comprises a helicase-like ATPase core coupled to two domains that provide specificity for preprotein translocation.

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More than one-third of cellular proteomes traffic into and across membranes. Bacteria have invented several sophisticated secretion systems that guide various proteins to extracytoplasmic locations and in some cases inject them directly into hosts. Of these, the Sec system is ubiquitous, essential and by far the best understood.

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Various studies demonstrate that immunosuppression vis-à-vis paternal alloantigens may play a role for successful pregnancy. However, if this theory is true, the question that remains unanswered is how do syngeneic pregnancies manage to produce viable embryos. In allogeneic murine pregnancies immunosuppression is mediated by regulatory CD25(+)/Foxp3/CTLA-4 T cells.

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