scholarly journals Crystal structure of RahU, an aegerolysin protein from the human pathogen Pseudomonas aeruginosa, and its interaction with membrane ceramide phosphorylethanolamine

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Eva Kočar ◽  
Tea Lenarčič ◽  
Vesna Hodnik ◽  
Anastasija Panevska ◽  
Yunjie Huang ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
High Frequency ◽  
Common Property ◽  
Insect Cell Line ◽  
Single Amino Acid ◽  
Head Group ◽  
Human Pathogens ◽  
Starting Point ◽  
Genome Analyses

AbstractAegerolysins are proteins produced by bacteria, fungi, plants and protozoa. The most studied fungal aegerolysins share a common property of interacting with membranes enriched with cholesterol in combination with either sphingomyelin or ceramide phosphorylethanolamine (CPE), major sphingolipids in the cell membranes of vertebrates and invertebrates, respectively. However, genome analyses show a particularly high frequency of aegerolysin genes in bacteria, including the pathogenic genera Pseudomonas and Vibrio; these are human pathogens of high clinical relevance and can thrive in a variety of other species. The knowledge on bacterial aegerolysin-lipid interactions is scarce. We show that Pseudomonas aeruginosa aegerolysin RahU interacts with CPE, but not with sphingomyelin-enriched artificial membranes, and that RahU interacts with the insect cell line producing CPE. We report crystal structures of RahU alone and in complex with tris(hydroxymethyl)aminomethane (Tris), which, like the phosphorylethanolamine head group of CPE, contains a primary amine. The RahU structures reveal that the two loops proximal to the amino terminus form a cavity that accommodates Tris, and that the flexibility of these two loops is important for this interaction. We show that Tris interferes with CPE-enriched membranes for binding to RahU, implying on the importance of the ligand cavity between the loops and its proximity in RahU membrane interaction. We further support this by studying the interaction of single amino acid substitution mutants of RahU with the CPE-enriched membranes. Our results thus represent a starting point for a better understanding of the role of P. aeruginosa RahU, and possibly other bacterial aegerolysins, in bacterial interactions with other organisms.

scholarly journals Functional Characterization of the Pseudomonas aeruginosa Ribosome Hibernation-Promoting Factor

2020 ◽  
Vol 202 (19) ◽  
Author(s):  
Michael J. Franklin ◽  
Elizabeth Sandvik ◽  
Sila Yanardag ◽  
Kerry S. Williamson
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Bacterial Species ◽  
Point Mutations ◽  
Single Amino Acid ◽  
Physiological Changes ◽  
Alpha Helices ◽  
Content Type ◽  
Charged Residues ◽  
Bacterial Starvation

ABSTRACT Hibernation-promoting factor (HPF) is a ribosomal accessory protein that inactivates ribosomes during bacterial starvation. In Pseudomonas aeruginosa, HPF protects ribosome integrity while the cells are dormant. The sequence of HPF has diverged among bacteria but contains conserved charged amino acids in its two alpha helices that interact with the rRNA. Here, we characterized the function of HPF in P. aeruginosa by performing mutagenesis of the conserved residues and then assaying mutant HPF alleles for their ability to protect ribosome integrity of starved P. aeruginosa cells. The results show that HPF functionally tolerates point mutations in charged residues and in the conserved Y71 residue as well as a C-terminal truncation. Double and triple mutations of charged residues in helix 1 in combination with a Y71F substitution reduce HPF activity. Screening for single point mutations that caused impaired HPF activity identified additional substitutions in the two HPF alpha helices. However, alanine substitutions in equivalent positions restored HPF activity, indicating that HPF is tolerant to mutations that do not disrupt the protein structure. Surprisingly, heterologous HPFs from Gram-positive bacteria that have long C-terminal domains functionally complement the P. aeruginosa Δhpf mutant, suggesting that HPF may play a similar role in ribosome protection in other bacterial species. Collectively, the results show that HPF has diverged among bacteria and is tolerant to most single amino acid substitutions. The Y71 residue in combination with helix 1 is important for the functional role of HPF in ribosome protection during bacterial starvation and resuscitation of the bacteria from dormancy. IMPORTANCE In most environments, bacteria experience conditions where nutrients may be readily abundant or where nutrients are limited. Under nutrient limitation conditions, even non-spore-forming bacteria may enter a dormant state. Dormancy is accompanied by a variety of cellular physiological changes that are required for the cells to remain viable during dormancy and to resuscitate when nutrients become available. Among the physiological changes that occur in dormant bacteria is the inactivation and preservation of ribosomes by the dormancy protein, hibernation-promoting factor (HPF). In this study, we characterized the activity of HPF of Pseudomonas aeruginosa, an opportunistic pathogen that causes persistent infections, and analyzed the role of HPF in ribosome protection and bacterial survival during dormancy.

scholarly journals GES-18, a New Carbapenem-Hydrolyzing GES-Type β-Lactamase from Pseudomonas aeruginosa That Contains Ile80 and Ser170 Residues

2012 ◽  
Vol 57 (1) ◽  
pp. 396-401 ◽  
Author(s):  
Carine Bebrone ◽  
Pierre Bogaerts ◽  
Heinrich Delbrück ◽  
Sandra Bennink ◽  
Michaël B. Kupper ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Lower Respiratory Tract ◽  
Resistance Mechanism ◽  
Single Amino Acid ◽  
Content Type ◽  
Reference Center ◽  
National Reference ◽  
National Reference Center ◽  
Similar Kinetic

ABSTRACTA clinical isolate ofPseudomonas aeruginosarecovered from the lower respiratory tract of an 81-year-old patient hospitalized in Belgium was sent to the national reference center to determine its resistance mechanism. PCR sequencing identified a new GES variant, GES-18, which differs from the carbapenem-hydrolyzing enzyme GES-5 by a single amino acid substitution (Val80Ile, in the numbering according to Ambler) and from GES-1 by two substitutions (Val80Ile and Gly170Ser). Detailed kinetic characterization showed that GES-18 and GES-5 hydrolyze imipenem and cefoxitin with similar kinetic parameters and that GES-18 was less susceptible than GES-1 to classical β-lactamase inhibitors such as clavulanate and tazobactam. The overall structure of GES-18 is similar to the solved structures of GES-1 and GES-2, the Val80Ile and Gly170Ser substitutions causing only subtle local rearrangements. Notably, the hydrolytic water molecule and the Glu166 residue were slightly displaced compared to their counterparts in GES-1. Our kinetic and crystallographic data for GES-18 highlight the pivotal role of the Gly170Ser substitution which distinguishes GES-5 and GES-18 from GES-1.

scholarly journals The role of toxin:antitoxin systems and insertion sequences in the loss of virulence in Shigella sonnei

2020 ◽  
Author(s):  
Jessica E. Martyn ◽  
Giulia Pilla ◽  
Sarah Hollingshead ◽  
Mariya Lobanovska ◽  
Kristoffer S. Winther ◽  
...  
Keyword(s):  
Type Iii Secretion ◽  
High Frequency ◽  
Shigella Flexneri ◽  
Shigella Sonnei ◽  
Single Amino Acid ◽  
Amino Acid Difference ◽  
Insertion Sequences ◽  
Plasmid Loss ◽  
The Impact

SUMMARYThe Shigella plasmid, pINV, contains a 30 kb pathogenicity island (PAI) encoding a Type III secretion system (T3SS) which is essential for virulence. During growth in the laboratory, avirulent colonies of Shigella (which do not express a T3SS) arise spontaneously. Avirulence in Shigella flexneri mostly follows loss of the PAI, following recombination between insertion sequences (ISs) on pINV; toxin:antitoxin (TA) systems on pINV promote its retention through post-segregational killing (PSK). We show that avirulence in Shigella sonnei mainly results from plasmid loss, consistent with previous findings; IS-mediated PAI deletions can occur in S. sonnei, but through different ISs than in S. flexneri. We investigated the molecular basis for frequent loss of the S. sonnei plasmid, pINVSsonn. Introduction into pINVSsonn of CcdAB and GmvAT, toxin:antitoxin TA systems in pINV from S. flexneri but not S. sonnei, reduced plasmid loss and the emergence of avirulent bacteria. However, plasmid loss remained the leading cause of avirulence. We show that a single amino acid difference in the VapC toxin of the VapBC TA system in pINV also contributes to high frequency plasmid loss in S. sonnei compared to S. flexneri. Our findings demonstrate that the repertoire of ISs, complement of TA systems, and polymorphisms in TA systems influence plasmid dynamics and virulence loss in S. sonnei. Understanding the impact of polymorphisms should be informative about how TA systems contribute to PSK, and could be exploited for generating strains with stable plasmids.

INTERPRETATION OF SINO-RUSSIAN CULTURE AND HUMANITIES COOPERATION IN THE NEW ERA

2020 ◽  
Vol 10 (3) ◽  
pp. 186-193
Author(s):  
REN YANYAN ◽  
Keyword(s):  
Current Status ◽  
Human Relations ◽  
New Era ◽  
Russian Culture ◽  
The People ◽  
Starting Point ◽  
Cooperative Partnership ◽  
Belt And Road ◽  
The Belt And Road

The friendship between nations lies in the mutual affinity of the people, and the people’s affinity lies in the communion of hearts. The cultural and humanities cooperation between China and Russia has a long history. In recent years, under the role of the“Belt and Road” initiative, the SCO, and the Sino-Russian Humanities Cooperation Committee, Sino-Russian culture and humanities cooperation has continued to deepen. Entering a new era, taking the opportunity to promote Sino-Russian relations into a “new era China-Russia comprehensive strategic cooperative partnership”, the development of human relations between the two countries has entered a new historical starting point, while also facing a series of problems and challenges. This article is based on the current status of Sino-Russian human relations in the new era, interprets the characteristics of Sino-Russian human relations in the new era, analyzes the problems and challenges of Sino-Russian human relations in the new era, and tries to propose solutions and solutions with a view to further developing Sino-Russian cultural and humanities relations in the new era. It is a useful reference, and provides a reference for future related research, and ultimately helps the Sino-Russian cultural and humanities relations in the new era to be stable and far-reaching.

Calculation-and-experimental estimation of the role of the frequency ratio in changing the endurance at two-frequency deformation modes

2019 ◽  
Vol 85 (1(I)) ◽  
pp. 64-71 ◽  
Author(s):  
M. M. Gadenin
Keyword(s):  
High Frequency ◽  
Experimental Studies ◽  
Low Frequency ◽  
Reduction Factor ◽  
Single Frequency ◽  
Cyclic Loads ◽  
Small Ratio ◽  
Harmonic Components ◽  
Deformation Modes

The cycle configuration at two-frequency loading regimes depends on the number of parameters including the absolute values of the frequencies and amplitudes of the low-frequency and high-frequency loads added during this mode, the ratio of their frequencies and amplitudes, as well as the phase shift between these harmonic components, the latter having a significant effect only with a small ratio of frequencies. Presence of such two-frequency regimes or service loading conditions for parts of machines and structures schematized by them can significantly reduce their endurance. Using the results of experimental studies of changes in the endurance of a two-frequency loading of specimens of cyclically stable, cyclically softened and cyclically hardened steels under rigid conditions we have shown that decrease in the endurance under the aforementioned conditions depends on the ratio of frequencies and amplitudes of operation low-frequency low-cycle and high-frequency vibration stresses, and, moreover, the higher the level of the ratios of amplitudes and frequencies of those stacked harmonic processes of loading the greater the effect. It is shown that estimation of such a decrease in the endurance compared to a single frequency loading equal in the total stress (strains) amplitudes can be carried out using an exponential expression coupling those endurances through a parameter (reduction factor) containing the ratio of frequencies and amplitudes of operation cyclic loads and characteristic of the material. The reduction is illustrated by a set of calculation-experimental curves on the corresponding diagrams for each of the considered types of materials and compared with the experimental data.

Role of rhizobia in suppressing the root rot and root knot disease of chili used alone or with Pseudomonas aeruginosa

2019 ◽  
Vol 52 (3) ◽  
Author(s):  
Gulnaz Parveen ◽  
Faizah Urooj ◽  
Hafiza Asma Shafique ◽  
Afshan Rahman ◽  
Syed Ehteshamul Haque
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Root Rot

La conexión entre política de cohesión y gobernanza económica en la UE: Eficiencia del nuevo marco para abordar las consecuencias de la crisis

2015 ◽  
Vol 5 (3) ◽  
pp. 44-62
Author(s):  
Laura Gómez Urquijo
Keyword(s):  
Social Protection ◽  
Economic Governance ◽  
The European Union ◽  
Investment Funds ◽  
Current Economic Crisis ◽  
Starting Point ◽  
New Economic Governance ◽  
Social Protection Systems ◽  
New Instruments

The objective of this article is to contribute to the discussion on the validity of new instruments to enhance cohesion in the European Union (EU). First, we question to which extent cohesion policy is submitted to the new economic governance. Second, we discuss this subordination affects the fulfillment of cohesion aims. This question is especially relevant due to the increase of inequalities in the current economic crisis and the great diversity among State Members (including social protection systems and expenses). Thus, our starting point is the new economic governance framework and its impact on the fulfillment of cohesion objectives. Statistical data are considered with this aim. Next, we will assess the role of European Structural and Investment Funds to eventually compensate public expense cuts, as well as its subordination to the macroeconomic government. This aspect will be contrasted through the study of Country Specific Recommendations given by the European Semester. Spanish El objetivo de este artículo es contribuir a la discusión sobre la validez de los nuevos instrumentos para fomentar la cohesión en la Unión Europea. Nos preguntamos en qué modo queda sometida la política de cohesión a la nueva gobernanza económica y cómo afecta a la efectividad para cubrir susfines. Esta cuestión es particularmente relevante ante el incremento de las desigualdades suscitado en la crisis económica actual. Por ello, nuestro punto de partida es el nuevo marco de gobernanza económica y su impacto en el cumplimiento de los objetivos de cohesión, considerando para ello datos estadísticos. A continuación, valoraremos, el papel de los Fondos Estructurales y de Inversión Europeos como posibles compensadores de la reducción del gasto público así como su subordinación al gobierno macroeconómico. Esta cuestión será contrastada también a través del examen de las Recomendaciones Específicas por país dadas por el Semestre Europeo. French Le but de cet article est de contribuer à la discussion sur la validité de nouveaux instruments pour promouvoir la cohésion dans l'UE. Nous avons considéré, d'une part, en quoi la politique de cohésion est soumise à la nouvelle gouvernance économique et, d'autre part, la façon dont elle utilise l'efficacité pour répondre à ses fins.Cette question est particulièrement pertinente étant donnée l'augmentation de l'inégalité soulevée par la crise économique actuelle, dans un contexte de grande diversité d'États membres, notamment en ce qui concerne les systèmes de protection sociale et les dépenses publiques. Par conséquent, notre point de départ s'inscrit dans le nouveau cadre de gouvernance économique et son impact sur la mise en œuvre des objectifs de cohésion, à partir de la prise en compte de données statistiques. Pour ce faire, nous évaluons le rôle des Fonds Structurels Européens, leur capacité de compenser la réduction des dépenses publiques et leur subordination au gouvernement macroéconomique. Ce e question sera également abordée par l'examen des recommandations spécifiques par pays fournies par le Semestre Européen.

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