scholarly journals Pocket Factors Are Unlikely To Play a Major Role in the Life Cycle of Human Rhinovirus

2007 ◽  
Vol 81 (12) ◽  
pp. 6307-6315 ◽  
Author(s):  
Umesh Katpally ◽  
Thomas J. Smith
Keyword(s):  
Life Cycle ◽  
Host Cell ◽  
Cell Attachment ◽  
Limited Proteolysis ◽  
Genetic Material ◽  
Binding Pocket ◽  
Drug Binding ◽  
Human Rhinovirus ◽  
Mouth Disease Virus ◽  
Binding Cavity

ABSTRACT Human rhinovirus 14 (HRV14) is a member of the rhinovirus genus, which belongs to the picornavirus family, which includes clinically and economically important members, such as poliovirus, foot-and-mouth disease virus, and endomyocarditis virus. Capsid stability plays an important role in the viral infection process, in that it needs to be stable enough to move from cell to cell and yet be able to release its genetic material upon the appropriate environmental cues from the host cell. It has been suggested that certain host cell molecules, “pocket factors,” bind to the WIN drug-binding cavity beneath the canyon floor and provide transient stability to a number of the picornaviruses. To directly test this hypothesis, HRV14 was mutated in (V1188M, C1199W, and V1188M/C1199W) and around (S1223G) the drug-binding pocket. Infectivity, limited proteolysis, and matrix-assisted laser desorption ionization analyses indicate that filling the drug-binding pocket with bulky side chains is not deleterious to the viral life cycle and lends some stabilization to the capsid. In contrast, studies with the S1223G mutant suggest that this mutation at least partially overcomes WIN drug-mediated inhibition of cell attachment and capsid breathing. Finally, HRV16, which is inherently more stable than HRV14 in a number of respects, was found to “breathe” only at 37°C and did not tolerate stabilizing mutations in the drug-binding cavity. These results suggest that it is the drug-binding cavity itself and not the putative pocket factor that is crucial for the capsid dynamics, which is, in turn, necessary for infection.

scholarly journals Structural and Virological Studies of the Stages of Virus Replication That Are Affected by Antirhinovirus Compounds

2004 ◽  
Vol 78 (20) ◽  
pp. 11061-11069 ◽  
Author(s):  
Ying Zhang ◽  
Alan A. Simpson ◽  
Rebecca M. Ledford ◽  
Carol M. Bator ◽  
Sugoto Chakravarty ◽  
...  
Keyword(s):  
Antiviral Activity ◽  
Virus Replication ◽  
Cell Attachment ◽  
Antiviral Effect ◽  
Binding Pocket ◽  
Drug Binding ◽  
Binding Studies ◽  
Hydrophobic Pocket ◽  
Viral Protein 1 ◽  
Inhibition Studies

ABSTRACT Pleconaril is a broad-spectrum antirhinovirus and antienterovirus compound that binds into a hydrophobic pocket within viral protein 1, stabilizing the capsid and resulting in the inhibition of cell attachment and RNA uncoating. When crystals of human rhinovirus 16 (HRV16) and HRV14 are incubated with pleconaril, drug occupancy in the binding pocket is lower than when pleconaril is introduced during assembly prior to crystallization. This effect is far more marked in HRV16 than in HRV14 and is more marked with pleconaril than with other compounds. These observations are consistent with virus yield inhibition studies and radiolabeled drug binding studies showing that the antiviral effect of pleconaril against HRV16 is greater on the infectivity of progeny virions than the parent input viruses. These data suggest that drug integration into the binding pocket during assembly, or at some other late stage in virus replication, may contribute to the antiviral activity of capsid binding compounds.

scholarly journals A survey of the kinome pharmacopeia reveals multiple scaffolds and targets for the development of novel anthelmintics

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jessica Knox ◽  
Nicolas Joly ◽  
Edmond M. Linossi ◽  
José A. Carmona-Negrón ◽  
Natalia Jura ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Developmental Delay ◽  
Small Molecule ◽  
Parasitic Nematode ◽  
Kinase Inhibitor ◽  
Binding Pocket ◽  
Drug Binding ◽  
Nematode Infection ◽  
Selective Inhibitors ◽  
C Elegans

AbstractOver one billion people are currently infected with a parasitic nematode. Symptoms can include anemia, malnutrition, developmental delay, and in severe cases, death. Resistance is emerging to the anthelmintics currently used to treat nematode infection, prompting the need to develop new anthelmintics. Towards this end, we identified a set of kinases that may be targeted in a nematode-selective manner. We first screened 2040 inhibitors of vertebrate kinases for those that impair the model nematode Caenorhabditis elegans. By determining whether the terminal phenotype induced by each kinase inhibitor matched that of the predicted target mutant in C. elegans, we identified 17 druggable nematode kinase targets. Of these, we found that nematode EGFR, MEK1, and PLK1 kinases have diverged from vertebrates within their drug-binding pocket. For each of these targets, we identified small molecule scaffolds that may be further modified to develop nematode-selective inhibitors. Nematode EGFR, MEK1, and PLK1 therefore represent key targets for the development of new anthelmintic medicines.

scholarly journals Crystal structure of steroid reductase SRD5A reveals conserved steroid reduction mechanism

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yufei Han ◽  
Qian Zhuang ◽  
Bo Sun ◽  
Wenping Lv ◽  
Sheng Wang ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Biochemical Characterization ◽  
Substrate Binding ◽  
Binding Pocket ◽  
Substrate Binding Pocket ◽  
Transmembrane Segments ◽  
Therapeutic Molecules ◽  
Binding Cavity ◽  
Immune System Regulation ◽  
Mediated Reduction

AbstractSteroid hormones are essential in stress response, immune system regulation, and reproduction in mammals. Steroids with 3-oxo-Δ4 structure, such as testosterone or progesterone, are catalyzed by steroid 5α-reductases (SRD5As) to generate their corresponding 3-oxo-5α steroids, which are essential for multiple physiological and pathological processes. SRD5A2 is already a target of clinically relevant drugs. However, the detailed mechanism of SRD5A-mediated reduction remains elusive. Here we report the crystal structure of PbSRD5A from Proteobacteria bacterium, a homolog of both SRD5A1 and SRD5A2, in complex with the cofactor NADPH at 2.0 Å resolution. PbSRD5A exists as a monomer comprised of seven transmembrane segments (TMs). The TM1-4 enclose a hydrophobic substrate binding cavity, whereas TM5-7 coordinate cofactor NADPH through extensive hydrogen bonds network. Homology-based structural models of HsSRD5A1 and -2, together with biochemical characterization, define the substrate binding pocket of SRD5As, explain the properties of disease-related mutants and provide an important framework for further understanding of the mechanism of NADPH mediated steroids 3-oxo-Δ4 reduction. Based on these analyses, the design of therapeutic molecules targeting SRD5As with improved specificity and therapeutic efficacy would be possible.

scholarly journals Perturbations in the surface structure of A22 Iraq foot-and-mouth disease virus accompanying coupled changes in host cell specificity and antigenicity

Structure ◽  
1996 ◽  
Vol 4 (2) ◽  
pp. 135-145 ◽  
Author(s):  
Stephen Curry ◽  
Elizabeth Fry ◽  
Wendy Blakemore ◽  
Robin Abu Ghazaleh ◽  
Terry Jackson ◽  
...  
Keyword(s):  
Surface Structure ◽  
Host Cell ◽  
Disease Virus ◽  
Foot And Mouth Disease ◽  
Mouth Disease ◽  
Cell Specificity ◽  
Mouth Disease Virus ◽  
Foot And Mouth

scholarly journals Structural basis for subtype-specific inhibition of the P2X7 receptor

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Akira Karasawa ◽  
Toshimitsu Kawate
Keyword(s):  
P2x7 Receptor ◽  
Hydrophobic Interactions ◽  
Binding Pocket ◽  
Drug Binding ◽  
Structural Basis ◽  
Atp Binding ◽  
Allosteric Site ◽  
Channel Opening ◽  
A Site ◽  
Novel Drug

The P2X7 receptor is a non-selective cation channel activated by extracellular adenosine triphosphate (ATP). Chronic activation of P2X7 underlies many health problems such as pathologic pain, yet we lack effective antagonists due to poorly understood mechanisms of inhibition. Here we present crystal structures of a mammalian P2X7 receptor complexed with five structurally-unrelated antagonists. Unexpectedly, these drugs all bind to an allosteric site distinct from the ATP-binding pocket in a groove formed between two neighboring subunits. This novel drug-binding pocket accommodates a diversity of small molecules mainly through hydrophobic interactions. Functional assays propose that these compounds allosterically prevent narrowing of the drug-binding pocket and the turret-like architecture during channel opening, which is consistent with a site of action distal to the ATP-binding pocket. These novel mechanistic insights will facilitate the development of P2X7-specific drugs for treating human diseases.

scholarly journals Single-Cell Analysis of the Impact of Host Cell Heterogeneity on Infection with Foot-and-Mouth Disease Virus

2018 ◽  
Vol 92 (9) ◽  
pp. e00179-18 ◽  
Author(s):  
Xiu Xin ◽  
Hailong Wang ◽  
Lingling Han ◽  
Mingzhen Wang ◽  
Hui Fang ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Single Cell ◽  
Host Cell ◽  
Cell Size ◽  
Single Cell Analysis ◽  
Foot And Mouth Disease ◽  
Cell Analysis ◽  
Cell Heterogeneity ◽  
Mouth Disease Virus ◽  
Foot And Mouth

ABSTRACTViral infection and replication are affected by host cell heterogeneity, but the mechanisms underlying the effects remain unclear. Using single-cell analysis, we investigated the effects of host cell heterogeneity, including cell size, inclusion, and cell cycle, on foot-and-mouth disease virus (FMDV) infection (acute and persistent infections) and replication. We detected various viral genome replication levels in FMDV-infected cells. Large cells and cells with a high number of inclusions generated more viral RNA copies and viral protein and a higher proportion of infectious cells than other cells. Additionally, we found that the viral titer was 10- to 100-fold higher in cells in G2/M than those in other cell cycle phases and identified a strong correlation between cell size, inclusion, and cell cycle heterogeneity, which all affected the infection and replication of FMDV. Furthermore, we demonstrated that host cell heterogeneity influenced the adsorption of FMDV due to differences in the levels of FMDV integrin receptors expression. Collectively, these results further our understanding of the evolution of a virus in a single host cell.IMPORTANCEIt is important to understand how host cell heterogeneity affects viral infection and replication. Using single-cell analysis, we found that viral genome replication levels exhibited dramatic variability in foot-and-mouth disease virus (FMDV)-infected cells. We also found a strong correlation between heterogeneity in cell size, inclusion number, and cell cycle status and that all of these characteristics affect the infection and replication of FMDV. Moreover, we found that host cell heterogeneity influenced the viral adsorption as differences in the levels of FMDV integrin receptors' expression. This study provided new ideas for the studies of correlation between FMDV infection mechanisms and host cells.

Life Cycles

2001 ◽  
Author(s):  
Jan A. Pechenik
Keyword(s):  
Life Cycle ◽  
Genetic Material ◽  
Life Cycles ◽  
Offspring Size ◽  
Free Living ◽  
Complex Life Cycles ◽  
Volume Number ◽  
Larval Stages ◽  
Underlying Mechanisms ◽  
Life Cycle Evolution

I have a Hardin cartoon on my office door. It shows a series of animals thinking about the meaning of life. In sequence, we see a lobe-finned fish, a salamander, a lizard, and a monkey, all thinking, “Eat, survive, reproduce; eat, survive, reproduce.” Then comes man: “What's it all about?” he wonders. Organisms live to reproduce. The ultimate selective pressure on any organism is to survive long enough and well enough to pass genetic material to a next generation that will also be successful in reproducing. In this sense, then, every morphological, physiological, biochemical, or behavioral adaptation contributes to reproductive success, making the field of life cycle evolution a very broad one indeed. Key components include mode of sexuality, age and size at first reproduction (Roff, this volume), number of reproductive episodes in a lifetime, offspring size (Messina and Fox, this volume), fecundity, the extent to which parents protect their offspring and how that protection is achieved, source of nutrition during development, survival to maturity, the consequences of shifts in any of these components, and the underlying mechanisms responsible for such shifts. Many of these issues are dealt with in other chapters. Here I focus exclusively on animals, and on a particularly widespread sort of life cycle that includes at least two ecologically distinct free-living stages. Such “complex life cycles” (Istock 1967) are especially common among amphibians and fishes (Hall and Wake 1999), and within most invertebrate groups, including insects (Gilbert and Frieden 1981), crustaceans, bivalves, gastropods, polychaete worms, echinoderms, bryozoans, and corals and other cnidarians (Thorson 1950). In such life cycles, the juvenile or adult stage is reached by metamorphosing from a preceding, free-living larval stage. In many species, metamorphosis involves a veritable revolution in morphology, ecology, behavior, and physiology, sometimes taking place in as little as a few minutes or a few hours. In addition to the issues already mentioned, key components of such complex life cycles include the timing of metamorphosis (i.e., when it occurs), the size at which larvae metamorphose, and the consequences of metamorphosing at particular times or at particular sizes. The potential advantages of including larval stages in the life history have been much discussed.

scholarly journals Reversing the direction of drug transport mediated by the human multidrug transporter P-glycoprotein

2020 ◽  
Vol 117 (47) ◽  
pp. 29609-29617
Author(s):  
Andaleeb Sajid ◽  
Sabrina Lusvarghi ◽  
Megumi Murakami ◽  
Eduardo E. Chufan ◽  
Biebele Abel ◽  
...  
Keyword(s):  
Drug Transport ◽  
Atp Hydrolysis ◽  
Binding Pocket ◽  
Drug Binding ◽  
Drug Uptake ◽  
Cancer Drug ◽  
Binding Domains ◽  
Cancer Drug Resistance ◽  
P Glycoprotein ◽  
Cell Transforming

P-glycoprotein (P-gp), also known as ABCB1, is a cell membrane transporter that mediates the efflux of chemically dissimilar amphipathic drugs and confers resistance to chemotherapy in most cancers. Homologous transmembrane helices (TMHs) 6 and 12 of human P-gp connect the transmembrane domains with its nucleotide-binding domains, and several residues in these TMHs contribute to the drug-binding pocket. To investigate the role of these helices in the transport function of P-gp, we substituted a group of 14 conserved residues (seven in both TMHs 6 and 12) with alanine and generated a mutant termed 14A. Although the 14A mutant lost the ability to pump most of the substrates tested out of cancer cells, surprisingly, it acquired a new function. It was able to import four substrates, including rhodamine 123 (Rh123) and the taxol derivative flutax-1. Similar to the efflux function of wild-type P-gp, we found that uptake by the 14A mutant is ATP hydrolysis-, substrate concentration-, and time-dependent. Consistent with the uptake function, the mutant P-gp also hypersensitizes HeLa cells to Rh123 by 2- to 2.5-fold. Further mutagenesis identified residues from both TMHs 6 and 12 that synergistically form a switch in the central region of the two helices that governs whether a given substrate is pumped out of or into the cell. Transforming P-gp or an ABC drug exporter from an efflux transporter into a drug uptake pump would constitute a paradigm shift in efforts to overcome cancer drug resistance.

scholarly journals A structure-based rationale for sialic acid independent host-cell entry of Sosuga virus

2019 ◽  
Vol 116 (43) ◽  
pp. 21514-21520 ◽  
Author(s):  
Alice J. Stelfox ◽  
Thomas A. Bowden
Keyword(s):  
Sialic Acid ◽  
Host Cell ◽  
Receptor Binding ◽  
Cell Attachment ◽  
Cell Entry ◽  
Head Region ◽  
Close Proximity ◽  
Host Cell Attachment ◽  
Host Cell Entry

The bat-borne paramyxovirus, Sosuga virus (SosV), is one of many paramyxoviruses recently identified and classified within the newly established genus Pararubulavirus, family Paramyxoviridae. The envelope surface of SosV presents a receptor-binding protein (RBP), SosV-RBP, which facilitates host-cell attachment and entry. Unlike closely related hemagglutinin neuraminidase RBPs from other genera of the Paramyxoviridae, SosV-RBP and other pararubulavirus RBPs lack many of the stringently conserved residues required for sialic acid recognition and hydrolysis. We determined the crystal structure of the globular head region of SosV-RBP, revealing that while the glycoprotein presents a classical paramyxoviral six-bladed β-propeller fold and structurally classifies in close proximity to paramyxoviral RBPs with hemagglutinin-neuraminidase (HN) functionality, it presents a receptor-binding face incongruent with sialic acid recognition. Hemadsorption and neuraminidase activity analysis confirms the limited capacity of SosV-RBP to interact with sialic acid in vitro and indicates that SosV-RBP undergoes a nonclassical route of host-cell entry. The close overall structural conservation of SosV-RBP with other classical HN RBPs supports a model by which pararubulaviruses only recently diverged from sialic acid binding functionality.

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