The structure of the PapD-PapGII pilin complex reveals an open and flexible P5 pocket

P pili are hairlike polymeric structures that mediate binding of uropathogenic Escherichia coli to the surface of the kidney via the PapG adhesin at their tips. PapG is composed of two domains: a lectin domain at the tip of the pilus followed by a pilin domain that comprises the initial polymerizing subunit of the 1,000-plus-subunit heteropolymeric pilus fiber. Prior to assembly, periplasmic pilin domains bind to a chaperone, PapD. PapD mediates donor strand complementation, in which a beta strand of PapD temporarily completes the pilin domain's fold, preventing premature, nonproductive interactions with other pilin subunits and facilitating subunit folding. Chaperone-subunit complexes are delivered to the outer membrane usher where donor strand exchange (DSE) replaces PapD's donated beta strand with an amino-terminal extension on the next incoming pilin subunit. This occurs via a zip-in-zip-out mechanism that initiates at a relatively accessible hydrophobic space termed the P5 pocket on the terminally incorporated pilus subunit. Here, we solve the structure of PapD in complex with the pilin domain of isoform II of PapG (PapGIIp). Our data revealed that PapGIIp adopts an immunoglobulin fold with a missing seventh strand, complemented in parallel by the G1 PapD strand, typical of pilin subunits. Comparisons with other chaperone-pilin complexes indicated that the interactive surfaces are highly conserved. Interestingly, the PapGIIp P5 pocket was in an open conformation, which, as molecular dynamics simulations revealed, switches between an open and a closed conformation due to the flexibility of the surrounding loops. Our study reveals the structural details of the DSE mechanism

Дослідження течії в лабіринтовому ущільненні

This scientific paper is devoted to the studies of labyrinth seals, because advanced system studies were not carried out to a sufficient extent. The efficiency of the centrifugal compressor can be increased by improving the impermeability of internal labyrinth seals. Today we have no rigorous theory of labyrinth seals and the system technique that takes into consideration constructive peculiarities and processes that occur in the labyrinth seals is also not available. The available conceptions are based on the Stodol formula, supplemented by the coefficients that are based on very limited number of test data and those were obtained in conditions far from being real. This paper gives proper consideration to the flow in the labyrinth seals taking into consideration many key operational and geometric parameters. The investigation was carried out using the developed technique for numeric and experimental investigations. The obtained data have been described; some of them were already known to us, in particular the influence of the shaft rate, nonuniformity of the pressure distribution along the seal length, and the values of local flow velocity coefficients, etc.). For the first time the seal was described in detail as a system of holes (slots), defining simultaneously individual characteristics of the slots and comparing them to the integral values of flow rate characteristics. Abnormal phenomena in the flow section of the multislot labyrinth seal in the form of zones with different modes of vortex flow have been revealed. Visual patterns of the flow structure in the seals were obtained. The obtained data can be used for further investigation of labyrinth seals and also for working out recommendations on how to increase their efficiency.Представлены результаты численного и физического моделирования лабиринтного уплотнения.Численное исследование проводилось с использованием программного комплекса Flow Vision, афизическое – на специальном экспериментальном стенде. Выполнен ряд исследований влияниярежимных и некоторых геометрических параметров на работу лабиринтного уплотнения: перепадауплотняемого давления, частоты вращения вала, радиального зазора, и др. Установлена зависимостьусловного коэффициента расхода лабиринтного уплотнения от частоты вращения вала, величиныотношения давления перед и за уплотнением. Показано влияние распределения давления по длинеуплотнения на его условный коэффициент расхода.Представлені результати чисельного і фізичного моделювання лабіринтового ущільнення. Чисельне дослідження проводилося з використанням програмного комплексу Flow Vision, а фізичне – на спеціальному експериментальному стенді. Виконаний ряд досліджень впливу режимних і деяких геометричних параметрів на роботу лабіринтового ущільнення: перепаду ущільнюваного тиску, частоти обертання валу, радіального зазору, та ін. Встановлена залежність умовного коефіцієнта витрати лабіринтового ущільнення від частоти обертання валу, величини відношення тиску перед і за ущільненням. Показаний вплив розподіл тиску по довжині ущільнення на його умовний коефіцієнт витрати

Early-onset Dopamine Transporter Deficiency Syndrome: Long-term Follow-up

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Paroxysmal movement disorder with response to carbamazepine in a patient with RHOBTB2 developmental and epileptic encephalopathy

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Alga-Produced Malaria Transmission-Blocking Vaccine Candidate Pfs25 Formulated with a Human Use-Compatible Potent Adjuvant Induces High-Affinity Antibodies That Block Plasmodium falciparum Infection of Mosquitoes

A vaccine to prevent the transmission of malaria parasites from infected humans to mosquitoes is an important component for the elimination of malaria in the 21st century, yet it remains neglected as a priority of malaria vaccine development. The lead candidate for Plasmodium falciparum transmission-blocking vaccine development, Pfs25, is a sexual stage surface protein that has been produced for vaccine testing in a variety of heterologous expression systems. Any realistic malaria vaccine will need to optimize proper folding balanced against cost of production, yield, and potentially reactogenic contaminants. Here Chlamydomonas reinhardtii microalga-produced recombinant Pfs25 protein was formulated with four different human-compatible adjuvants (alum, Toll-like receptor 4 [TLR-4] agonist glucopyranosal lipid A [GLA] plus alum, squalene–oil-in-water emulsion, and GLA plus squalene–oil-in-water emulsion) and compared for their ability to induce malaria transmission-blocking antibodies. Alga-produced recombinant Pfs25 plus GLA plus squalene–oil-in-water adjuvant induced the highest titer and avidity in IgG antibodies, measured using alga-produced recombinant Pfs25 as the enzyme-linked immunosorbent assay (ELISA) antigen. These antibodies specifically reacted with the surface of P. falciparum macrogametes and zygotes and effectively prevented parasites from developing within the mosquito vector in standard membrane feeding assays. Alga-produced Pfs25 in combination with a human-compatible adjuvant composed of a TLR-4 agonist in a squalene–oil-in-water emulsion is an attractive new vaccine candidate that merits head-to-head comparison with other modalities of vaccine production and administration

Alga-Produced Malaria Transmission-Blocking Vaccine Candidate Pfs25 Formulated with a Human Use-Compatible Potent Adjuvant Induces High-Affinity Antibodies That Block Plasmodium falciparum Infection of Mosquitoes

A vaccine to prevent the transmission of malaria parasites from infected humans to mosquitoes is an important component for the elimination of malaria in the 21st century, yet it remains neglected as a priority of malaria vaccine development. The lead candidate for Plasmodium falciparum transmission-blocking vaccine development, Pfs25, is a sexual stage surface protein that has been produced for vaccine testing in a variety of heterologous expression systems. Any realistic malaria vaccine will need to optimize proper folding balanced against cost of production, yield, and potentially reactogenic contaminants. Here Chlamydomonas reinhardtii microalga-produced recombinant Pfs25 protein was formulated with four different human-compatible adjuvants (alum, Toll-like receptor 4 [TLR-4] agonist glucopyranosal lipid A [GLA] plus alum, squalene-oil-in-water emulsion, and GLA plus squalene-oil-in-water emulsion) and compared for their ability to induce malaria transmission-blocking antibodies. Alga-produced recombinant Pfs25 plus GLA plus squalene-oil-in-water adjuvant induced the highest titer and avidity in IgG antibodies, measured using alga-produced recombinant Pfs25 as the enzyme-linked immunosorbent assay (ELISA) antigen. These antibodies specifically reacted with the surface of P. falciparum macrogametes and zygotes and effectively prevented parasites from developing within the mosquito vector in standard membrane feeding assays. Alga-produced Pfs25 in combination with a human-compatible adjuvant composed of a TLR-4 agonist in a squalene-oil-in-water emulsion is an attractive new vaccine candidate that merits head-to-head comparison with other modalities of vaccine production and administration