Vestiges of the Bacterial Signal Recognition Particle-Based Protein Targeting in Mitochondria.

The main bacterial pathway for inserting proteins into the plasma membrane relies on the signal recognition particle (SRP), composed of the Ffh protein and an associated RNA component, and the SRP-docking protein FtsY. Eukaryotes use an equivalent system of archaeal origin to deliver proteins into the endoplasmic reticulum, whereas a bacteria-derived SRP and FtsY function in the plastid. Here we report on the presence of homologs of the bacterial Ffh and FtsY proteins in various unrelated plastid-lacking unicellular eukaryotes, namely Heterolobosea, Alveida, Goniomonas, and Hemimastigophora. The monophyly of novel eukaryotic Ffh and FtsY groups, predicted mitochondrial localization experimentally confirmed for Naegleria gruberi, and a strong alphaproteobacterial affinity of the Ffh group, collectively suggest that they constitute parts of an ancestral mitochondrial signal peptide-based protein-targeting system inherited from the last eukaryotic common ancestor, but lost from the majority of extant eukaryotes. The ability of putative signal peptides, predicted in a subset of mitochondrial-encoded N. gruberi proteins, to target a reporter fluorescent protein into the endoplasmic reticulum of Trypanosoma brucei, likely through their interaction with the cytosolic SRP, provided further support for this notion. We also illustrate that known mitochondrial ribosome-interacting proteins implicated in membrane protein targeting in opisthokonts (Mba1, Mdm38, and Mrx15) are broadly conserved in eukaryotes and nonredundant with the mitochondrial SRP system. Finally, we identified a novel mitochondrial protein (MAP67) present in diverse eukaryotes and related to the signal peptide-binding domain of Ffh, which may well be a hitherto unrecognized component of the mitochondrial membrane protein-targeting machinery.

Characterization of FtsY, its interaction with Ffh, and proteomic identification of their potential substrates in Mycobacterium tuberculosis.

The universally conserved signal recognition particle (SRP) pathway that mediates co-translational targeting of membrane and secretory proteins is essential for eukaryotic and prokaryotic cells. The Mycobacterium tuberculosis SRP pathway consists of 2 proteins, Ffh and FtsY, and a 4.5S RNA molecule. Although the Escherichia coli SRP pathway is well studied, understanding of the M. tuberculosis SRP pathway components is very limited. In this study, we have overexpressed and characterized the M. tuberculosis SRP receptor (SR) FtsY as a GTP binding protein. Further, we established the direct protein-protein interaction between Ffh and FtsY. The Ffh-FtsY complex formation resulted in mutual stimulation of their GTP hydrolysis activity. We also attempted to biochemically characterize the SRP components by constructing the antisense gene knockdown strains of ffh and ftsY in M. tuberculosis. Loss of ffh and ftsY resulted in a decreased in vitro growth rate of the antisense ffh strain as compared with the antisense ftsY strain. Finally, 2-D gel electrophoresis of antisense depleted ffh and ftsY strains identified differential expression of 14 proteins.

Comprehensive factor analysis and risk quantification study of fall from height accidents.

Working at heights poses frequent and significant risks, demanding scientific approaches for investigating fall-from-height (FFH) incidents and proposing preventive measures to enhance building safety. Nevertheless, ongoing research on analyzing the causal factors behind fall-from-height accidents lacks a comprehensive qualitative and quantitative assessment of the interplay between these factors. To bridge this gap, this study introduces an integrated risk analysis model. Utilizing incident reports and leveraging the multi-case rootedness theory, the model initially identifies influential elements. Subsequently, employing the Grey Decision Making Laboratory (Grey-DEMATEL) and Interpretive Structural Modeling (ISM) techniques, a hierarchical network is constructed, followed by the transformation of this hierarchical network model into a Bayesian Network (BN) model using GeNie2.0 software. Ultimately, the study was based on data from 420 accident cases and analyzed the causes and diagnosis of the accidents. The findings indicate that A5 (Low-security awareness) is the most significant factor contributing to falls from great heights and that the connection between the components is dynamic and non-linear rather than simply independent and linear. Furthermore, the study established a likelihood of occurrence of such incidents of up to 57 % and ranked the probability of occurrence of each contributing component in the case of a fall from height. This study presents a scientifically valid method for analyzing fall-from-height accidents. Experimental results confirm the model's applicability, empowering contractors to improve safety management by accessing precise risk information and prioritizing preventive measures against interrelated accidents. The model facilitates informed decision-making for contractors to effectively mitigate fall-from-height risks and establish a safer working environment.

Flood risk assessment for residences at the neighborhood scale by owner/occupant type and first-floor height.

Evaluating flood risk is an essential component of understanding and increasing community resilience. A robust approach for quantifying flood risk in terms of average annual loss (AAL) in dollars across multiple homes is needed to provide valuable information for stakeholder decision-making. This research develops a computational framework to evaluate AAL at the neighborhood level by owner/occupant type (i.e., homeowner, landlord, and tenant) for increasing first-floor height (FFH). The AAL values were calculated here by numerically integrating loss-exceedance probability distributions to represent economic annual flood risk to the building, contents, and use. A simple case study for a census block in Jefferson Parish, Louisiana, revealed that homeowners bear a mean AAL of $4,390 at the 100-year flood elevation (E 100), compared with $2,960, and $1,590 for landlords and tenants, respectively, because the homeowner incurs losses to building, contents, and use, rather than only two of the three, as for the landlord and tenant. The results of this case study showed that increasing FFH reduces AAL proportionately for each owner/occupant type, and that two feet of additional elevation above E 100 may provide the most economically advantageous benefit. The modeled results suggested that Hazus Multi-Hazard (Hazus-MH) output underestimates the AAL by 11% for building and 15% for contents. Application of this technique while partitioning the owner/occupant types will improve planning for improved resilience and assessment of impacts attributable to the costly flood hazard.

Fine interaction profiling of VemP and mechanisms responsible for its translocation-coupled arrest-cancelation.

Bacterial cells utilize monitoring substrates, which undergo force-sensitive translation elongation arrest, to feedback-regulate a Sec-related gene. Vibrio alginolyticus VemP controls the expression of SecD/F that stimulates a late step of translocation by undergoing export-regulated elongation arrest. Here, we attempted at delineating the pathway of the VemP nascent-chain interaction with Sec-related factors, and identified the signal recognition particle (SRP) and PpiD (a membrane-anchored periplasmic chaperone) in addition to other translocon components and a ribosomal protein as interacting partners. Our results showed that SRP is required for the membrane-targeting of VemP, whereas PpiD acts cooperatively with SecD/F in the translocation and arrest-cancelation of VemP. We also identified the conserved Arg-85 residue of VemP as a crucial element that confers PpiD-dependence to VemP and plays an essential role in the regulated arrest-cancelation. We propose a scheme of the arrest-cancelation processes of VemP, which likely monitors late steps in the protein translocation pathway.

Membrane proteomic analysis reveals overlapping and independent functions of Streptococcus mutans Ffh, YidC1, and YidC2.

A comparative proteomic analysis was utilized to evaluate similarities and differences in membrane samples derived from the cariogenic bacterium Streptococcus mutans, including the wild-type strain and four mutants devoid of protein translocation machinery components, specifically ∆ffh, ∆yidC1, ∆yidC2, or ∆ffh/yidC1. The purpose of this work was to determine the extent to which the encoded proteins operate individually or in concert with one another and to identify the potential substrates of the respective pathways. Ffh is the principal protein component of the signal recognition particle (SRP), while yidC1 and yidC2 are dual paralogs encoding members of the YidC/Oxa/Alb family of membrane-localized chaperone insertases. Our results suggest that the co-translational SRP pathway works in concert with either YidC1 or YidC2 specifically, or with no preference for paralog, in the insertion of most membrane-localized substrates. A few instances were identified in which the SRP pathway alone, or one of the YidCs alone, appeared to be most relevant. These data shed light on underlying reasons for differing phenotypic consequences of ffh, yidC1 or yidC2 deletion. Our data further suggest that many membrane proteins present in a ∆yidC2 background may be non-functional, that ∆yidC1 is better able to adapt physiologically to the loss of this paralog, that shared phenotypic properties of ∆ffh and ∆yidC2 mutants can stem from impacts on different proteins, and that independent binding to ribosomal proteins is not a primary functional activity of YidC2. Lastly, genomic mutations accumulate in a ∆yidC2 background coincident with phenotypic reversion, including an apparent W138R suppressor mutation within yidC1.

Comparative Review on the Cost-Effectiveness Analysis of Relief Teams' Deployment to Sudden-Onset Disasters.

When a disaster exceeds the capacity of the affected country to cope with its own resources, the provision of external rescue and health services is required, and the deployment of relief units requested. Recently, the cost of international relief and the belief that such deployment is cost-effective has been questioned by the international community; unfortunately, there is still little informed debate and few detailed data are available. This paper presents the results of a comparative review on the cost-effectiveness analysis (CEA) of search and rescue (SAR) and Emergency Medical Team (EMT) deployment. The aim of this work is to provide an overview of the topic, highlight the criteria used to assess the effectiveness, and identify gaps in existing literature. The results show that both deployments are highly expensive, and their success is strongly related to the time they need to be operational; SAR deployments are characterized by limited outcomes in terms of lives saved, and EMTs by insufficient data and lack of detailed assessment. This research highlights that the criteria used to assess the effectiveness need to be explored further, considering different purposes, lengths of stay, and different activities performed, especially for any comparison. This study concludes that data reporting should be mandatory for humanitarian response agencies.