Over the billions of years that bacteria have been around, they have evolved several sophisticated protein secretion nanomachines to deliver toxins, hydrolytic enzymes, and effector proteins into their environments. Of these, the type II secretion system (T2SS) is used by Gram-negative bacteria to export a wide range of folded proteins from the periplasm across the outer membrane. Recent findings have demonstrated that components of the T2SS are localized in mitochondria of some eukaryotic lineages, and their behavior is consistent with the presence of a mitochondrial T2SS-derived system (miT2SS). This review focuses on recent advances in the field and discusses open questions concerning the function and evolution of miT2SSs.

• Klíčová slova
• T2SS, evolution, mitochondria, mitochondrial evolution, protein secretion, protein transport, type II secretion system,
• MeSH
• bakteriální proteiny genetika   metabolismus   MeSH
• bakteriální sekreční systémy metabolismus   MeSH
• gramnegativní bakterie metabolismus   MeSH
• periplazma metabolismus   MeSH
• sekreční systém typu II * metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• bakteriální proteiny MeSH
• bakteriální sekreční systémy MeSH
• sekreční systém typu II * MeSH

The classical Bordetella species infect the respiratory tract of mammals. While B. bronchiseptica causes rather chronic respiratory infections in a variety of mammals, the human-adapted species B. pertussis and B. parapertussisHU cause an acute respiratory disease known as whooping cough or pertussis. The virulence factors include a type III secretion system (T3SS) that translocates effectors BteA and BopN into host cells. However, the regulatory mechanisms underlying the secretion and translocation activity of T3SS in bordetellae are largely unknown. We have solved the crystal structure of BopN of B. pertussis and show that it is similar to the structures of gatekeepers that control access to the T3SS channel from the bacterial cytoplasm. We further found that BopN accumulates at the cell periphery at physiological concentrations of calcium ions (2 mM) that inhibit the secretion of BteA and BopN. Deletion of the bopN gene in B. bronchiseptica increased secretion of the BteA effector into calcium-rich medium but had no effect on secretion of the T3SS translocon components BopD and BopB. Moreover, the ΔbopN mutant secreted approximately 10-fold higher amounts of BteA into the medium of infected cells than the wild-type bacteria, but it translocated lower amounts of BteA into the host cell cytoplasm. These data demonstrate that BopN is a Bordetella T3SS gatekeeper required for regulated and targeted translocation of the BteA effector through the T3SS injectisome into host cells. IMPORTANCE The T3SS is utilized by many Gram-negative bacteria to deliver effector proteins from bacterial cytosol directly into infected host cell cytoplasm in a regulated and targeted manner. Pathogenic bordetellae use the T3SS to inject the BteA and BopN proteins into infected cells and upregulate the production of the anti-inflammatory cytokine interleukin-10 (IL-10) to evade host immunity. Previous studies proposed that BopN acted as an effector in host cells. In this study, we report that BopN is a T3SS gatekeeper that regulates the secretion and translocation activity of Bordetella T3SS.

• Klíčová slova
• BopN, Bordetella, gatekeeper, type III secretion system,
• MeSH
• bakteriální proteiny metabolismus   MeSH
• Bordetella pertussis metabolismus   MeSH
• faktory virulence metabolismus   MeSH
• lidé MeSH
• pertuse * MeSH
• savci MeSH
• sekreční systém typu III * metabolismus   MeSH
• vápník MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• bakteriální proteiny MeSH
• faktory virulence MeSH
• sekreční systém typu III * MeSH
• vápník MeSH

Pertussis, also known as whooping cough, is a resurging acute respiratory disease of humans primarily caused by the Gram-negative coccobacilli Bordetella pertussis, and less commonly by the human-adapted lineage of B. parapertussisHU. The ovine-adapted lineage of B. parapertussisOV infects only sheep, while B. bronchiseptica causes chronic and often asymptomatic respiratory infections in a broad range of mammals but rarely in humans. A largely overlapping set of virulence factors inflicts the pathogenicity of these bordetellae. Their genomes also harbor a pathogenicity island, named bsc locus, that encodes components of the type III secretion injectosome, and adjacent btr locus with the type III regulatory proteins. The Bsc injectosome of bordetellae translocates the cytotoxic BteA effector protein, also referred to as BopC, into the cells of the mammalian hosts. While the role of type III secretion activity in the persistent colonization of the lower respiratory tract by B. bronchiseptica is well recognized, the functionality of the type III secretion injectosome in B. pertussis was overlooked for many years due to the adaptation of laboratory-passaged B. pertussis strains. This review highlights the current knowledge of the type III secretion system in the so-called classical Bordetella species, comprising B. pertussis, B. parapertussis, and B. bronchiseptica, and discusses its functional divergence. Comparison with other well-studied bacterial injectosomes, regulation of the type III secretion on the transcriptional and post-transcriptional level, and activities of BteA effector protein and BopN protein, homologous to the type III secretion gatekeepers, are addressed.

• Klíčová slova
• BopN, Bordetella, BteA/BopC, effector protein, pertussis, type III secretion system,
• MeSH
• bakteriální proteiny genetika   MeSH
• Bordetella bronchiseptica * MeSH
• Bordetella pertussis genetika   MeSH
• faktory virulence genetika   MeSH
• infekce bakteriemi rodu Bordetella * MeSH
• ovce MeSH
• sekreční systém typu III genetika   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• bakteriální proteiny MeSH
• faktory virulence MeSH
• sekreční systém typu III MeSH

Fatty acid (FA)-stimulated insulin secretion (FASIS) is reviewed here in contrast to type 2 diabetes etiology, resulting from FA overload, oxidative stress, intermediate hyperinsulinemia, and inflammation, all converging into insulin resistance. Focusing on pancreatic islet β-cells, we compare the physiological FA roles with the pathological ones. Considering FAs not as mere amplifiers of glucose-stimulated insulin secretion (GSIS), but as parallel insulin granule exocytosis inductors, partly independent of the KATP channel closure, we describe the FA initiating roles in the prediabetic state that is induced by retardations in the glycerol-3-phosphate (glucose)-promoted glycerol/FA cycle and by the impaired GPR40/FFA1 (free FA1) receptor pathway, specifically in its amplification by the redox-activated mitochondrial phospholipase, iPLA2γ. Also, excessive dietary FAs stimulate intestine enterocyte incretin secretion, further elevating GSIS, even at low glucose levels, thus contributing to diabetic hyperinsulinemia. With overnutrition and obesity, the FA overload causes impaired GSIS by metabolic dysbalance, paralleled by oxidative and metabolic stress, endoplasmic reticulum stress and numerous pro-apoptotic signaling, all leading to decreased β-cell survival. Lipotoxicity is exerted by saturated FAs, whereas ω-3 polyunsaturated FAs frequently exert antilipotoxic effects. FA-facilitated inflammation upon the recruitment of excess M1 macrophages into islets (over resolving M2 type), amplified by cytokine and chemokine secretion by β-cells, leads to an inevitable failure of pancreatic β-cells.

• Klíčová slova
• GPR40, fatty acid-stimulated insulin secretion, fatty acids, lipotoxicity, low-grade inflammation, oxidative stress, pancreatic β-cells, type 2 diabetes,
• MeSH
• beta-buňky * metabolismus   patologie   MeSH
• hyperinzulinismus * metabolismus   patologie   MeSH
• inzulin metabolismus   MeSH
• inzulinová rezistence * MeSH
• lidé MeSH
• mastné kyseliny metabolismus   MeSH
• oxidační stres * MeSH
• sekrece inzulinu MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH
• Názvy látek
• inzulin MeSH
• mastné kyseliny MeSH

Repeats-in-Toxin (RTX) proteins of Gram-negative bacteria are excreted through the type I secretion system (T1SS) that recognizes non-cleavable C-terminal secretion signals. These are preceded by arrays of glycine and aspartate-rich nonapeptide repeats grouped by four to eight β strands into blocks that fold into calcium-binding parallel β-roll structures. The β-rolls are interspersed by linkers of variable length and sequence and the organization of multiple RTX repeat blocks within large RTX domains remains unknown. Here we examined the structure and function of the RTX domain of Bordetella pertussis adenylate cyclase toxin (CyaA) that is composed of five β-roll RTX blocks. We show that the non-folded RTX repeats maintain the stability of the CyaA polypeptide in the Ca2+-depleted bacterial cytosol and thereby enable its efficient translocation through the T1SS apparatus. The efficacy of secretion of truncated CyaA constructs was dictated by the number of retained RTX repeat blocks and depended on the presence of extracellular Ca2+ ions. We further describe the crystal structure of the RTX blocks IV-V of CyaA (CyaA1372-1681) that consists of a contiguous assembly of two β-rolls that differs substantially from the arrangement of the RTX blocks observed in RTX lipases or other RTX proteins. These results provide a novel structural insight into the architecture of the RTX domains of large RTX proteins and support the "push-ratchet" mechanism of the T1SS-mediated secretion of very large RTX proteins.

• Klíčová slova
• Bordetella pertussis, RTX proteins, adenylate cyclase toxins, type I secretion system,
• MeSH
• adenylátcyklasový toxin chemie   genetika   metabolismus   MeSH
• bakteriální proteiny chemie   metabolismus   MeSH
• bakteriální toxiny chemie   genetika   metabolismus   MeSH
• Bordetella pertussis metabolismus   MeSH
• cytosol metabolismus   MeSH
• gramnegativní bakterie metabolismus   MeSH
• konformace proteinů MeSH
• sbalování proteinů MeSH
• sekreční systém typu I MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• adenylátcyklasový toxin MeSH
• bakteriální proteiny MeSH
• bakteriální toxiny MeSH
• sekreční systém typu I MeSH

Significance: Mitochondria determine glucose-stimulated insulin secretion (GSIS) in pancreatic β-cells by elevating ATP synthesis. As the metabolic and redox hub, mitochondria provide numerous links to the plasma membrane channels, insulin granule vesicles (IGVs), cell redox, NADH, NADPH, and Ca2+ homeostasis, all affecting insulin secretion. Recent Advances: Mitochondrial redox signaling was implicated in several modes of insulin secretion (branched-chain ketoacid [BCKA]-, fatty acid [FA]-stimulated). Mitochondrial Ca2+ influx was found to enhance GSIS, reflecting cytosolic Ca2+ oscillations induced by action potential spikes (intermittent opening of voltage-dependent Ca2+ and K+ channels) or the superimposed Ca2+ release from the endoplasmic reticulum (ER). The ATPase inhibitory factor 1 (IF1) was reported to tune the glucose sensitivity range for GSIS. Mitochondrial protein kinase A was implicated in preventing the IF1-mediated inhibition of the ATP synthase. Critical Issues: It is unknown how the redox signal spreads up to the plasma membrane and what its targets are, what the differences in metabolic, redox, NADH/NADPH, and Ca2+ signaling, and homeostasis are between the first and second GSIS phase, and whether mitochondria can replace ER in the amplification of IGV exocytosis. Future Directions: Metabolomics studies performed to distinguish between the mitochondrial matrix and cytosolic metabolites will elucidate further details. Identifying the targets of cell signaling into mitochondria and of mitochondrial retrograde metabolic and redox signals to the cell will uncover further molecular mechanisms for insulin secretion stimulated by glucose, BCKAs, and FAs, and the amplification of secretion by glucagon-like peptide (GLP-1) and metabotropic receptors. They will identify the distinction between the hub β-cells and their followers in intact and diabetic states. Antioxid. Redox Signal. 36, 920-952.

• Klíčová slova
• ATP-sensitive K+ channel, GLP-1, TRPM channels, branched-chain ketoacid oxidation, fatty acid-stimulated insulin secretion, insulin secretion, mitochondrial Ca2+ transport, pancreatic β-cell metabolism, redox signaling,
• MeSH
• adenosintrifosfát metabolismus   MeSH
• beta-buňky * metabolismus   MeSH
• glukosa metabolismus   MeSH
• inzulin metabolismus   MeSH
• Langerhansovy ostrůvky * metabolismus   MeSH
• mitochondrie metabolismus   MeSH
• NAD metabolismus   MeSH
• NADP metabolismus   MeSH
• sekrece inzulinu MeSH
• sekretagoga metabolismus   MeSH
• vápník metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• adenosintrifosfát MeSH
• glukosa MeSH
• inzulin MeSH
• NAD MeSH
• NADP MeSH
• sekretagoga MeSH
• vápník MeSH

BACKGROUND: Ventilator-Associated Pneumonia (VAP) is an undesired side effect of mechanical ventilation in intensive care units (ICUs). AIM: We evaluated whether endotracheal tubes with subglottic secretion drainage (SSD) would reduce the incidence of VAP among patients undergoing mechanical ventilation in an ICU. METHODS: The analysis of medical records of patients undergoing mechanical ventilation exceeding 48 h who were hospitalised in ICUs between 2007 and 2014 led to separating two groups of patients: those in whom no subglottic drainage was applied (NSSD) (records dating from 2007-2010) and those whose treatment involved endotracheal tubes with subglottic secretion drainage (SSD) (records dating from 2011-2014). RESULTS: Analysis of 1807 patients hospitalised in ICUs (804 NSSD patients and 1003 SSD patients). A difference was found in the frequency of VAP incidence between the groups (P<0.001). In the NSSD group as many as 84 cases were reported (incidence: 10.7%), and in the SSD group - 43 cases (incidence: 5.2%). The odds ratio (OR) and relative risk (RR) was 2.5. The probability of VAP was significantly higher in the NSSD group. The risk factors of VAP incidence (P<0.001) included the correlation between reintubation (R=0.271), tracheostomy (R=0.309) and bronchoscopy (R=0.316). CONCLUSION: Use of endotracheal tubes with subglottic secretion drainage in patients in the ICU on mechanical ventilation significantly reduced the incidence of VAP.

• Klíčová slova
• endotracheal tube (ETT), subglottic secretion drainage (SSD), ventilator-associated pneumonia (VAP),
• MeSH
• dítě MeSH
• dospělí MeSH
• drenáž * přístrojové vybavení   MeSH
• glottis MeSH
• incidence MeSH
• intratracheální intubace škodlivé účinky   přístrojové vybavení   MeSH
• kojenec MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• předškolní dítě MeSH
• retrospektivní studie MeSH
• rizikové faktory MeSH
• senioři MeSH
• tělesné sekrety MeSH
• ventilátorová pneumonie epidemiologie   etiologie   prevence a kontrola   MeSH
• Check Tag
• dítě MeSH
• dospělí MeSH
• kojenec MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• předškolní dítě MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH

In this study we have compared protein secretion in the wild type of S. Typhimurium and the rfaC mutant. We found out that the rfaC mutant was defective in protein secretion. In addition, the rfaC mutant was defective in its invasion into an IPEC-J2 porcine epithelial cell line and also in motility in semisolid agar. Consistent with this, reduced flagella numbers were observed in the rfaC mutant. In the rfaC mutant, there were no defects in flagellin expression as detected by western blot and immune electron microscopy which demonstrated equal amounts of flagellin in the cytoplasm of both the rfaC mutant and the wild-type S. Typhimurium. However, in the wild-type strain only, the flagellin was assembled to spatially restricted areas on the inner side of cytoplasmic membrane. The oligosaccharide core of LPS is therefore required for the assembly of flagella and T3SS secretion machinery followed by protein secretion.

• MeSH
• bakteriální sekreční systémy * MeSH
• buněčné linie MeSH
• cytoplazma chemie   MeSH
• epitelové buňky mikrobiologie   MeSH
• flagelin biosyntéza   metabolismus   MeSH
• flagella metabolismus   MeSH
• imunoelektronová mikroskopie MeSH
• lipopolysacharidy chemie   MeSH
• mutace MeSH
• prasata MeSH
• Salmonella enterica genetika   metabolismus   ultrastruktura   MeSH
• sekvenční analýza hybridizací s uspořádaným souborem oligonukleotidů MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• bakteriální sekreční systémy * MeSH
• flagelin MeSH
• lipopolysacharidy MeSH

Bordetella pertussis, the causative agent of human whooping cough (pertussis) produces a complex array of virulence factors in order to establish efficient infection in the host. The RNA chaperone Hfq and small regulatory RNAs are key players in posttranscriptional regulation in bacteria and have been shown to play an essential role in virulence of a broad spectrum of bacterial pathogens. This study represents the first attempt to characterize the Hfq regulon of the human pathogen B. pertussis under laboratory conditions as well as upon passage in the host and indicates that loss of Hfq has a profound effect on gene expression in B. pertussis. Comparative transcriptional profiling revealed that Hfq is required for expression of several virulence factors in B. pertussis cells including the Type III secretion system (T3SS). In striking contrast to the wt strain, T3SS did not become operational in the hfq mutant passaged either through mice or macrophages thereby proving that Hfq is required for the functionality of the B. pertussis T3SS. Likewise, expression of virulence factors vag8 and tcfA encoding autotransporter and tracheal colonization factor, respectively, was strongly reduced in the hfq mutant. Importantly, for the first time we demonstrate that B. pertussis T3SS can be activated upon contact with macrophage cells in vitro.

• Klíčová slova
• ABC protein, ATP-binding cassette protein, Bsp22, CFU, colony forming unit, Hfq, OMP, outer membrane protein, P, P-value, RT-qPCR, quantitative reverse transcription polymerase chain reaction, SS medium, Steiner-Scholte medium, T3SS, T3SS, Type III secretion system, infection, transcriptomics, virulence, wt, wild-type,
• MeSH
• bakteriální proteiny genetika   metabolismus   MeSH
• bakteriální RNA genetika   metabolismus   MeSH
• Bordetella pertussis genetika   metabolismus   patogenita   MeSH
• buněčné linie MeSH
• faktory virulence rodu Bordetella genetika   metabolismus   MeSH
• infekce bakteriemi rodu Bordetella mikrobiologie   MeSH
• interakce hostitele a patogenu MeSH
• makrofágy metabolismus   mikrobiologie   MeSH
• myši MeSH
• protein hostitelského faktoru 1 nedostatek   genetika   MeSH
• regulace genové exprese u bakterií * MeSH
• regulon MeSH
• sekreční systém typu III genetika   metabolismus   MeSH
• sekreční systém typu V genetika   metabolismus   MeSH
• stanovení celkové genové exprese MeSH
• transkriptom MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• bakteriální proteiny MeSH
• bakteriální RNA MeSH
• faktory virulence rodu Bordetella MeSH
• protein hostitelského faktoru 1 MeSH
• sekreční systém typu III MeSH
• sekreční systém typu V MeSH
• tracheal colonization factor, Bordetella pertussis MeSH Prohlížeč

• Klíčová slova
• FPI, Francisella, IglE, T6SS,
• MeSH
• bakteriální proteiny MeSH
• faktory virulence MeSH
• Francisella tularensis * MeSH
• Francisella MeSH
• lidé MeSH
• makrofágy MeSH
• sekreční systém typu VI * MeSH
• tularemie MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• komentáře MeSH
• práce podpořená grantem MeSH
• úvodníky MeSH
• Názvy látek
• bakteriální proteiny MeSH
• faktory virulence MeSH
• sekreční systém typu VI * MeSH