scholarly journals Targeting Toxoplasma Tubules: Tubulin, Microtubules, and Associated Proteins in a Human Pathogen

2014 ◽  
Vol 14 (1) ◽  
pp. 2-12 ◽  
Author(s):  
Naomi Morrissette
Keyword(s):  
Opportunistic Infections ◽  
Genetic Recombination ◽  
Flagellar Apparatus ◽  
Content Type ◽  
Obligate Intracellular ◽  
Spiral Trajectory ◽  
Parasite Survival ◽  
Associated Proteins ◽  
Flagellar Axoneme

ABSTRACTToxoplasma gondiiis an obligate intracellular parasite that causes serious opportunistic infections, birth defects, and blindness in humans. Microtubules are critically important components of diverse structures that are used throughout theToxoplasmalife cycle. As in other eukaryotes, spindle microtubules are required for chromosome segregation during replication. Additionally, a set of membrane-associated microtubules is essential for the elongated shape of invasive “zoites,” and motility follows a spiral trajectory that reflects the path of these microtubules.Toxoplasmazoites also construct an intricate, tubulin-based apical structure, termed the conoid, which is important for host cell invasion and associates with proteins typically found in the flagellar apparatus. Last, microgametes specifically construct a microtubule-containing flagellar axoneme in order to fertilize macrogametes, permitting genetic recombination. The specialized roles of these microtubule populations are mediated by distinct sets of associated proteins. This review summarizes our current understanding of the role of tubulin, microtubule populations, and associated proteins inToxoplasma; these components are used for both novel and broadly conserved processes that are essential for parasite survival.

scholarly journals Conserved Regulators of Mating Are Essential for Aspergillus fumigatus Cleistothecium Formation

2010 ◽  
Vol 9 (5) ◽  
pp. 774-783 ◽  
Author(s):  
Edyta Szewczyk ◽  
Sven Krappmann
Keyword(s):  
Aspergillus Fumigatus ◽  
Genetic Recombination ◽  
Content Type ◽  
Hyphal Fusion ◽  
Expression Of Genes ◽  
Body Development ◽  
Fruiting Body Development ◽  
Genes Encoding ◽  
Long Time

ABSTRACT Sexual reproduction of the human pathogen Aspergillus fumigatus (teleomorph: Neosartorya fumigata) was assumed to be absent or cryptic until recently, when fertile crosses among geographically restricted environmental isolates were described. Here, we provide evidence for mating, fruiting body development, and ascosporogenesis accompanied by genetic recombination between unrelated, clinical isolates of A. fumigatus, and this evidence demonstrates the generality and reproducibility of this long-time-undisclosed phase in the life cycle of this heterothallic fungus. Successful mating requires the presence of both mating-type idiomorphs MAT1-1 and MAT1-2, as does expression of genes encoding factors presumably involved in this process. Moreover, analysis of an A. fumigatus mutant deleted for the nsdD gene suggests a role of this conserved regulator of cleistothecium development in hyphal fusion and hence heterokaryon formation.

scholarly journals Coordinated Regulation of the Size and Number of Polyhydroxybutyrate Granules by Core and Accessory Phasins in the Facultative Microsymbiont Sinorhizobium fredii NGR234

2019 ◽  
Vol 85 (19) ◽  
Author(s):  
Yan-Wei Sun ◽  
Yan Li ◽  
Yue Hu ◽  
Wen-Xin Chen ◽  
Chang-Fu Tian
Keyword(s):  
Broad Host Range ◽  
Metabolic Profiles ◽  
Free Living ◽  
Sinorhizobium Fredii ◽  
Content Type ◽  
Cellular Processes ◽  
Size Number ◽  
Associated Proteins ◽  
Auxiliary Gene

ABSTRACT The exact roles of various granule-associated proteins (GAPs) of polyhydroxybutyrate (PHB) are poorly investigated, particularly for bacteria associated with plants. In this study, four structural GAPs, named phasins PhaP1 to PhaP4, were identified and demonstrated as true phasins colocalized with PHB granules in Sinorhizobium fredii NGR234, a facultative microsymbiont of Vigna unguiculata and many other legumes. The conserved PhaP2 dominated in regulation of granule size under both free-living and symbiotic conditions. PhaP1, another conserved phasin, made a higher contribution than accessory phasins PhaP4 and PhaP3 to PHB biosynthesis at stationary phase. PhaP3, with limited phyletic distribution on the symbiosis plasmid of Sinorhizobium, was more important than PhaP1 in regulating PHB biosynthesis in V. unguiculata nodules. Under the test conditions, no significant symbiotic defects were observed for mutants lacking individual or multiple phaP genes. The mutant lacking two PHB synthases showed impaired symbiotic performance, while mutations in individual PHB synthases or a PHB depolymerase yielded no symbiotic defects. This phenomenon is not related to either the number or size of PHB granules in test mutants within nodules. Distinct metabolic profiles and cocktail pools of GAPs of different phaP mutants imply that core and accessory phasins can be differentially involved in regulating other cellular processes in the facultative microsymbiont S. fredii NGR234. IMPORTANCE Polyhydroxybutyrate (PHB) granules are a store of carbon and energy in bacteria and archaea and play an important role in stress adaptation. Recent studies have highlighted distinct roles of several granule-associated proteins (GAPs) in regulating the size, number, and localization of PHB granules in free-living bacteria, though our knowledge of the role of GAPs in bacteria associated with plants is still limited. Here we report distinct roles of core and accessory phasins associated with PHB granules of Sinorhizobium fredii NGR234, a broad-host-range microsymbiont of diverse legumes. Core phasins PhaP2 and PhaP1 are conserved major phasins in free-living cells. PhaP2 and accessory phasin PhaP3, encoded by an auxiliary gene on the symbiosis plasmid, are major phasins in nitrogen-fixing bacteroids in cowpea nodules. GAPs and metabolic profiles can vary in different phaP mutants. Contrasting symbiotic performances between mutants lacking PHB synthases, depolymerase, or phasins were revealed.

scholarly journals An Intracellular Peptidyl-Prolyl cis/trans Isomerase Is Required for Folding and Activity of the Staphylococcus aureus Secreted Virulence Factor Nuclease

2016 ◽  
Vol 199 (1) ◽  
Author(s):  
Richard E. Wiemels ◽  
Stephanie M. Cech ◽  
Nikki M. Meyer ◽  
Caleb A. Burke ◽  
Andy Weiss ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Cell Wall ◽  
Virulence Factors ◽  
Virulence Factor ◽  
Active Form ◽  
Ppiase Activity ◽  
Content Type ◽  
Associated Proteins

ABSTRACT Staphylococcus aureus is an important human pathogen that relies on a large repertoire of secreted and cell wall-associated proteins for pathogenesis. Consequently, the ability of the organism to cause disease is absolutely dependent on its ability to synthesize and successfully secrete these proteins. In this study, we investigate the role of peptidyl-prolyl cis/trans isomerases (PPIases) on the activity of the S. aureus secreted virulence factor nuclease (Nuc). We identify a staphylococcal cyclophilin-type PPIase (PpiB) that is required for optimal activity of Nuc. Disruption of ppiB results in decreased nuclease activity in culture supernatants; however, the levels of Nuc protein are not altered, suggesting that the decrease in activity results from misfolding of Nuc in the absence of PpiB. We go on to demonstrate that PpiB exhibits PPIase activity in vitro, is localized to the bacterial cytosol, and directly interacts with Nuc in vitro to accelerate the rate of Nuc refolding. Finally, we demonstrate an additional role for PpiB in S. aureus hemolysis and demonstrate that the S. aureus parvulin-type PPIase PrsA also plays a role in the activity of secreted virulence factors. The deletion of prsA leads to a decrease in secreted protease and phospholipase activity, similar to that observed in other Gram-positive pathogens. Together, these results demonstrate, for the first time to our knowledge, that PPIases play an important role in the secretion of virulence factors in S. aureus. IMPORTANCE Staphylococcus aureus is a highly dangerous bacterial pathogen capable of causing a variety of infections throughout the human body. The ability of S. aureus to cause disease is largely due to an extensive repertoire of secreted and cell wall-associated proteins, including adhesins, toxins, exoenzymes, and superantigens. These virulence factors, once produced, are typically transported across the cell membrane by the secretory (Sec) system in a denatured state. Consequently, once outside the cell, they must refold into their active form. This step often requires the assistance of bacterial folding proteins, such as PPIases. In this work, we investigate the role of PPIases in S. aureus and uncover a cyclophilin-type enzyme that assists in the folding/refolding of staphylococcal nuclease.

scholarly journals Identification and Characterization of the Rhoptry Neck Protein 2 in Babesia divergens and B. microti

2016 ◽  
Vol 84 (5) ◽  
pp. 1574-1584 ◽  
Author(s):  
Rosalynn L. Ord ◽  
Marilis Rodriguez ◽  
Jeny R. Cursino-Santos ◽  
Hyunryung Hong ◽  
Manpreet Singh ◽  
...  
Keyword(s):  
Direct Role ◽  
Parasite Invasion ◽  
Content Type ◽  
Apicomplexan Parasites ◽  
Babesia Divergens ◽  
Associated Proteins ◽  
Identification And Characterization

Apicomplexan parasites include those of the generaPlasmodium,Cryptosporidium, andToxoplasmaand those of the relatively understudied zoonotic genusBabesia. In humans, babesiosis, particularly transfusion-transmitted babesiosis, has been emerging as a major threat to public health. Like malaria, the disease pathology is a consequence of the parasitemia which develops through cyclical replication ofBabesiaparasites in host erythrocytes. However, there are no exoerythrocytic stages inBabesia, so targeting of the blood stage and associated proteins to directly prevent parasite invasion is the most desirable option for effective disease control. Especially promising among such molecules are the rhoptry neck proteins (RONs), whose homologs have been identified in many apicomplexan parasites. RONs are involved in the formation of the moving junction, along with AMA1, but no RON has been identified and characterized in anyBabesiaspp. Here we identify the RON2 proteins ofBabesia divergens(BdRON2) andB. microti(BmRON2) and show that they are localized apically and that anti-BdRON2 antibodies are significant inhibitors of parasite invasionin vitro. Neither protein is immunodominant, as both proteins react only marginally with sera from infected animals. Further characterization of the direct role of both BdRON2 and BmRON2 in parasite invasion is required, but knowledge of the level of conformity of RON2 proteins within the apicomplexan phylum, particularly that of the AMA1-RON2 complex at the moving junction, along with the availability of an animal model forB. microtistudies, provides a key to target this complex with a goal of preventing the erythrocytic invasion of these parasites and to further our understanding of the role of these conserved ligands in invasion.

scholarly journals Leishmania Encodes a Bacterium-like 2,4-Dienoyl-Coenzyme A Reductase That Is Required for Fatty Acid β-Oxidation and Intracellular Parasite Survival

mBio ◽  
2020 ◽  
Vol 11 (3) ◽  
Author(s):  
Geo Semini ◽  
Daniel Paape ◽  
Martin Blume ◽  
M. Fleur Sernee ◽  
Diego Peres-Alonso ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Gene Transfer ◽  
Intracellular Parasite ◽  
Protozoan Parasites ◽  
Content Type ◽  
Obligate Intracellular ◽  
Parasite Survival ◽  
Vertebrate Hosts ◽  
Coa Reductase

ABSTRACT Leishmania spp. are protozoan parasites that cause a spectrum of important diseases in humans. These parasites develop as extracellular promastigotes in the digestive tract of their insect vectors and as obligate intracellular amastigotes that infect macrophages and other phagocytic cells in their vertebrate hosts. Promastigote-to-amastigote differentiation is associated with marked changes in metabolism, including the upregulation of enzymes involved in fatty acid β-oxidation, which may reflect adaptation to the intracellular niche. Here, we have investigated the function of one of these enzymes, a putative 2,4-dienoyl-coenzyme A (CoA) reductase (DECR), which is specifically required for the β-oxidation of polyunsaturated fatty acids. The Leishmania DECR shows close homology to bacterial DECR proteins, suggesting that it was acquired by lateral gene transfer. It is present in other trypanosomatids that have obligate intracellular stages (i.e., Trypanosoma cruzi and Angomonas) but is absent from dixenous parasites with an exclusively extracellular lifestyle (i.e., Trypanosoma brucei). A DECR-green fluorescent protein (GFP) fusion protein was localized to the mitochondrion in both promastigote and amastigote stages, and the levels of expression increased in the latter stages. A Leishmania major Δdecr null mutant was unable to catabolize unsaturated fatty acids and accumulated the intermediate 2,4-decadienoyl-CoA, confirming DECR’s role in β-oxidation. Strikingly, the L. major Δdecr mutant was unable to survive in macrophages and was avirulent in BALB/c mice. These findings suggest that β-oxidation of polyunsaturated fatty acids is essential for intracellular parasite survival and that the bacterial origin of key enzymes in this pathway could be exploited in developing new therapies. IMPORTANCE The Trypanosomatidae are protozoan parasites that infect insects, plants, and animals and have evolved complex monoxenous (single host) and dixenous (two hosts) lifestyles. A number of species of Trypanosomatidae, including Leishmania spp., have evolved the capacity to survive within intracellular niches in vertebrate hosts. The adaptations, metabolic and other, that are associated with development of intracellular lifestyles remain poorly defined. We show that genomes of Leishmania and Trypanosomatidae that can survive intracellularly encode a 2,4-dienoyl-CoA reductase that is involved in catabolism of a subclass of fatty acids. The trypanosomatid enzyme shows closest similarity to the corresponding bacterial enzymes and is located in the mitochondrion and essential for intracellular growth of Leishmania. The findings suggest that acquisition of this gene by lateral gene transfer from bacteria by ancestral monoxenous Trypanosomatidae likely contributed to the development of a dixenous lifestyle of these parasites.

scholarly journals Interviral Recombination between Plant, Insect, and Fungal RNA Viruses: Role of the Intracellular Ca2+/Mn2+ Pump

2019 ◽  
Vol 94 (1) ◽  
Author(s):  
Nikolay Kovalev ◽  
Judit Pogany ◽  
Peter D. Nagy
Keyword(s):  
Driving Forces ◽  
Rna Viruses ◽  
Genetic Recombination ◽  
Hot Spot ◽  
Plant Viruses ◽  
Template Switching ◽  
Rna Recombination ◽  
Content Type ◽  
Intracellular Ca

ABSTRACT Recombination is one of the driving forces of viral evolution. RNA recombination events among similar RNA viruses are frequent, although RNA recombination could also take place among unrelated viruses. In this paper, we have established efficient interviral recombination systems based on yeast and plants. We show that diverse RNA viruses, including the plant viruses tomato bushy stunt virus, carnation Italian ringspot virus, and turnip crinkle virus-associated RNA; the insect plus-strand RNA [(+)RNA] viruses Flock House virus and Nodamura virus; and the double-stranded L-A virus of yeast, are involved in interviral recombination events. Most interviral recombinants are minus-strand recombinant RNAs, and the junction sites are not randomly distributed, but there are certain hot spot regions. Formation of interviral recombinants in yeast and plants is accelerated by depletion of the cellular SERCA-like Pmr1 ATPase-driven Ca2+/Mn2+ pump, regulating intracellular Ca2+ and Mn2+ influx into the Golgi apparatus from the cytosol. The interviral recombinants are generated by a template-switching mechanism during RNA replication by the viral replicase. Replication studies revealed that a group of interviral recombinants is replication competent in cell-free extracts, in yeast, and in the plant Nicotiana benthamiana. We propose that there are major differences among the viral replicases to generate and maintain interviral recombinants. Altogether, the obtained data promote the model that host factors greatly contribute to the formation of recombinants among related and unrelated viruses. This is the first time that a host factor’s role in affecting interviral recombination is established. IMPORTANCE Viruses with RNA genomes are abundant, and their genomic sequences show astonishing variation. Genetic recombination in RNA viruses is a major force behind their rapid evolution, enhanced pathogenesis, and adaptation to their hosts. We utilized a previously identified intracellular Ca2+/Mn2+ pump-deficient yeast to search for interviral recombinants. Noninfectious viral replication systems were used to avoid generating unwanted infectious interviral recombinants. Altogether, interviral RNA recombinants were observed between plant and insect viruses, and between a fungal double-stranded RNA (dsRNA) virus and an insect virus, in the yeast host. In addition, interviral recombinants between two plant virus replicon RNAs were identified in N. benthamiana plants, in which the intracellular Ca2+/Mn2+ pump was depleted. These findings underline the crucial role of the host in promoting RNA recombination among unrelated viruses.

scholarly journals Staphylococcus pseudintermediusSurface Protein L (SpsL) Is Required for Abscess Formation in a Murine Model of Cutaneous Infection

2018 ◽  
Vol 86 (11) ◽  
Author(s):  
Amy C. Richards ◽  
Marie O'Shea ◽  
Philippa M. Beard ◽  
Mariya I. Goncheva ◽  
Stephen W. Tuffs ◽  
...  
Keyword(s):  
Surface Protein ◽  
Antibiotic Use ◽  
Abscess Formation ◽  
Infection Model ◽  
Cutaneous Infection ◽  
Cutaneous Lesions ◽  
Content Type ◽  
Bacterial Surface ◽  
Associated Proteins

ABSTRACTStaphylococcus pseudintermediusis the leading cause of pyoderma in dogs and is often associated with recurrent skin infections that require prolonged antibiotic therapy. High levels of antibiotic use have led to multidrug resistance, including the emergence of epidemic methicillin-resistant clones. Our understanding of the pathogenesis ofS. pseudintermediusskin infection is very limited, and the identification of the key host-pathogen interactions underpinning infection could lead to the design of novel therapeutic or vaccine-based approaches for controlling disease. Here, we employ a novel murine cutaneous-infection model ofS. pseudintermediusand investigate the role of the two cell wall-associated proteins (SpsD and SpsL) in skin disease pathogenesis. Experimental infection with wild-typeS. pseudintermediusstrain ED99 or a gene-deletion derivative deficient in expression of SpsD led to a focal accumulation of neutrophils and necrotic debris in the dermis and deeper tissues of the skin characteristic of a classical cutaneous abscess. In contrast, mice infected with mutants deficient in SpsL or both SpsD and SpsL developed larger cutaneous lesions with distinct histopathological features of regionally extensive cellulitis rather than focal abscessation. Furthermore, comparison of the bacterial loads inS. pseudintermedius-induced cutaneous lesions revealed a significantly increased burden of bacteria in the mice infected with SpsL-deficient mutants. These findings reveal a key role for SpsL in murine skin abscess formation and highlight a novel function for a bacterial surface protein in determining the clinical outcome and pathology of infection caused by a major canine pathogen.

Long-term management of patients with multiple brain metastases after shaped beam radiosurgery

2004 ◽  
pp. 406-412
Author(s):  
Paul Okunieff ◽  
Michael C. Schell ◽  
Russell Ruo ◽  
E. Ronald Hale ◽  
Walter G. O'Dell ◽  
...  
Keyword(s):  
Brain Metastases ◽  
Tumor Control ◽  
Content Type ◽  
Negative Results ◽  
Multiple Metastases ◽  
Extracranial Disease ◽  
Successful Control ◽  
The Brain

✓ The role of radiosurgery in the treatment of patients with advanced-stage metastatic disease is currently under debate. Previous randomized studies have not consistently supported the use of radiosurgery to treat patients with numbers of brain metastases. In negative-results studies, however, intracranial tumor control was high but extracranial disease progressed; thus, patient survival was not greatly affected, although neurocognitive function was generally maintained until death. Because the future promises improved systemic (extracranial) therapy, the successful control of brain disease is that much more crucial. Thus, for selected patients with multiple metastases to the brain who remain in good neurological condition, aggressive lesion-targeting radiosurgery should be very useful. Although a major limitation to success of this therapy is the lack of control of extracranial disease in most patients, it is clear that well-designed, aggressive treatment substantially decreases the progression of brain metastases and also improves neurocognitive survival. The authors present the management and a methodology for rational treatment of a patient with breast cancer who has harbored 24 brain metastases during a 3-year period.

scholarly journals Vulnerable adults in police custody

2019 ◽  
Vol 22 (1) ◽  
pp. 5-8
Author(s):  
Ian Cummins
Keyword(s):  
Design Methodology ◽  
Research Literature ◽  
Police Custody ◽  
England And Wales ◽  
Content Type ◽  
Increased Risk ◽  
Vulnerable Adults

Purpose The purpose of this paper is to discuss the recent National Appropriate Adult Network (NAAN) report on the role of the appropriate adult. Design/methodology/approach This paper is based on the NAAN report and a review of relevant policy and research literature. Findings There to Help 2 highlights that there are still significant gaps in the provision of appropriate adult schemes across England and Wales. These gaps potentially place vulnerable adults at increased risk. Originality/value This paper is a review of recent research.

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