Ileana M. Cristea
Dec 1, 2005; 4:1933-1941
Research

Ilka Wittig
Jul 1, 2007; 6:1215-1225
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Ivan Matic
Jan 1, 2008; 7:132-144
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Hasmik Keshishian
Dec 1, 2007; 6:2212-2229
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Jonathan C. Trinidad
Aug 1, 2012; 11:215-229
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M. Wang
Aug 1, 2012; 11:492-500
Technological Innovation and Resources

Qin Liu
Aug 1, 2007; 6:1299-1317
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Mitsunori Fukuda
Jun 1, 2008; 7:1031-1042
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Jacek R. Wiśniewski
Dec 1, 2014; 13:3497-3506
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Tamar Geiger
Mar 1, 2012; 11:M111.014050-M111.014050
Special Issue: Prospects in Space and Time

Yi Zhang
Sep 1, 2005; 4:1240-1250
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Timothy J. Griffin
Apr 1, 2002; 1:323-333
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Amelia C. Peterson
Nov 1, 2012; 11:1475-1488
Technological Innovation and Resources

Sean R. Collins
Mar 1, 2007; 6:439-450
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Lawrence E. Ostrowski
Jun 1, 2002; 1:451-465
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Roland Bruderer
May 1, 2015; 14:1400-1410
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Sebastian A. Wagner
Oct 1, 2011; 10:M111.013284-M111.013284
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Joris J. Benschop
Jul 1, 2007; 6:1198-1214
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Christian Tagwerker
Apr 1, 2006; 5:737-748
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Guoan Chen
Apr 1, 2002; 1:304-313
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Qiang Tian
Oct 1, 2004; 3:960-969
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Alexey I. Nesvizhskii
Oct 1, 2005; 4:1419-1440
Tutorial

Jesper V. Olsen
Jun 1, 2004; 3:608-614
Technology

Yu Xue
Sep 1, 2008; 7:1598-1608
Research

William M. Old
Oct 1, 2005; 4:1487-1502
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Leigh Anderson
Apr 1, 2006; 5:573-588
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Mathias Uhlén
Dec 1, 2005; 4:1920-1932
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Claudio P. Albuquerque
Jul 1, 2008; 7:1389-1396
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Ludovic C. Gillet
Jun 1, 2012; 11:O111.016717-O111.016717
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Ignat V. Shilov
Sep 1, 2007; 6:1638-1655
Technology

Albrecht Gruhler
Mar 1, 2005; 4:310-327
Research

Martin R. Larsen
Jul 1, 2005; 4:873-886
Technology

Jeffrey C. Silva
Jan 1, 2006; 5:144-156
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N. Leigh Anderson
Nov 1, 2002; 1:845-867
Reviews/Perspectives

Ulrich Rothbauer
Feb 1, 2008; 7:282-289
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Yasushi Ishihama
Sep 1, 2005; 4:1265-1272
Research

Linn Fagerberg
Feb 1, 2014; 13:397-406
Research

Jesper V. Olsen
Dec 1, 2005; 4:2010-2021
Technology

Eiji Kinoshita
Apr 1, 2006; 5:749-757
Technology

Philip L. Ross
Dec 1, 2004; 3:1154-1169
Research

Jürgen Cox
Sep 1, 2014; 13:2513-2526
Technological Innovation and Resources

Shao-En Ong
May 1, 2002; 1:376-386
Research

Staphylococcus aureus adhesion to the host's skin and mucosae enables asymptomatic colonization and the establishment of infection. This process is facilitated by cell wall-anchored adhesins that bind to host ligands. Therapeutics targeting this process could provide significant clinical benefits; however, the development of anti-adhesives requires an in-depth knowledge of adhesion-associated factors and an assay amenable to high-throughput applications. Here, we describe the development of a sensitive and robust whole cell assay to enable the large-scale profiling of S. aureus adhesion to host ligands. To validate the assay, and to gain insight into cellular factors contributing to adhesion, we profiled a sequence-defined S. aureus transposon mutant library, identifying mutants with attenuated adhesion to human-derived fibronectin, keratin, and fibrinogen. Our screening approach was validated by the identification of known adhesion-related proteins, such as the housekeeping sortase responsible for covalently linking adhesins to the cell wall. In addition, we also identified genetic loci that could represent undescribed anti-adhesive targets. To compare and contrast the genetic requirements of adhesion to each host ligand, we generated a S. aureus Genetic Adhesion Network, which identified a core gene set involved in adhesion to all three host ligands, and unique genetic signatures. In summary, this assay will enable high-throughput chemical screens to identify anti-adhesives and our findings provide insight into the target space of such an approach.

Despite its major importance in human health, the metabolic potential of the human gut microbiota is still poorly understood. We have recently shown that biosynthesis of Ruminococcin C (RumC), a novel ribosomally synthesized and posttranslationally modified peptide (RiPP) produced by the commensal bacterium Ruminococcus gnavus, requires two radical SAM enzymes (RumMC1 and RumMC2) catalyzing the formation of four Cα-thioether bridges. These bridges, which are essential for RumC's antibiotic properties against human pathogens such as Clostridium perfringens, define two hairpin domains giving this sactipeptide (sulfur-to-α-carbon thioether–containing peptide) an unusual architecture among natural products. We report here the biochemical and spectroscopic characterizations of RumMC2. EPR spectroscopy and mutagenesis data support that RumMC2 is a member of the large family of SPASM domain radical SAM enzymes characterized by the presence of three [4Fe-4S] clusters. We also demonstrate that this enzyme initiates its reaction by Cα H-atom abstraction and is able to catalyze the formation of nonnatural thioether bonds in engineered peptide substrates. Unexpectedly, our data support the formation of a ketoimine rather than an α,β-dehydro-amino acid intermediate during Cα-thioether bridge LC–MS/MS fragmentation. Finally, we explored the roles of the leader peptide and of the RiPP precursor peptide recognition element, present in myriad RiPP-modifying enzymes. Collectively, our data support a more complex role for the peptide recognition element and the core peptide for the installation of posttranslational modifications in RiPPs than previously anticipated and suggest a possible reaction intermediate for thioether bond formation.

Leukocidin ED (LukED) is a pore-forming toxin produced by Staphylococcus aureus, which lyses host cells and promotes virulence of the bacteria. LukED enables S. aureus to acquire iron by lysing erythrocytes, which depends on targeting the host receptor Duffy antigen receptor for chemokines (DARC). The toxin also targets DARC on the endothelium, contributing to the lethality observed during bloodstream infection in mice. LukED is comprised of two monomers: LukE and LukD. LukE binds to DARC and facilitates hemolysis, but the closely related Panton–Valentine leukocidin S (LukS-PV) does not bind to DARC and is not hemolytic. The interaction of LukE with DARC and the role this plays in hemolysis are incompletely characterized. To determine the domain(s) of LukE that are critical for DARC binding, we studied the hemolytic function of LukE–LukS-PV chimeras, in which areas of sequence divergence (divergence regions, or DRs) were swapped between the toxins. We found that two regions of LukE's rim domain contribute to hemolysis, namely residues 57–75 (DR1) and residues 182–196 (DR4). Interestingly, LukE DR1 is sufficient to render LukS-PV capable of DARC binding and hemolysis. Further, LukE, by binding DARC through DR1, promotes the recruitment of LukD to erythrocytes, likely by facilitating LukED oligomer formation. Finally, we show that LukE targets murine Darc through DR1 in vivo to cause host lethality. These findings expand our biochemical understanding of the LukE–DARC interaction and the role that this toxin-receptor pair plays in S. aureus pathophysiology.

HIV Type 1 (HIV-1) and simian immunodeficiency virus (SIV) display differential replication kinetics in macrophages. This is because high expression levels of the active host deoxynucleotide triphosphohydrolase sterile α motif domain and histidine-aspartate domain–containing protein 1 (SAMHD1) deplete intracellular dNTPs, which restrict HIV-1 reverse transcription, and result in a restrictive infection in this myeloid cell type. Some SIVs overcome SAMHD1 restriction using viral protein X (Vpx), a viral accessory protein that induces proteasomal degradation of SAMHD1, increasing cellular dNTP concentrations and enabling efficient proviral DNA synthesis. We previously reported that SAMHD1-noncounteracting lentiviruses may have evolved to harbor RT proteins that efficiently polymerize DNA, even at low dNTP concentrations, to circumvent SAMHD1 restriction. Here we investigated whether RTs from SIVmac239 virus lacking a Vpx protein evolve during in vivo infection to more efficiently synthesize DNA at the low dNTP concentrations found in macrophages. Sequence analysis of RTs cloned from Vpx (+) and Vpx (−) SIVmac239–infected animals revealed that Vpx (−) RTs contained more extensive mutations than Vpx (+) RTs. Although the amino acid substitutions were dispersed indiscriminately across the protein, steady-state and pre-steady-state analysis demonstrated that selected SIVmac239 Vpx (−) RTs are characterized by higher catalytic efficiency and incorporation efficiency values than RTs cloned from SIVmac239 Vpx (+) infections. Overall, this study supports the possibility that the loss of Vpx may generate in vivo SIVmac239 RT variants that can counteract the limited availability of dNTP substrate in macrophages.

Candida albicans and Aspergillus fumigatus are dangerous fungal pathogens with high morbidity and mortality, particularly in immunocompromised patients. Innate immune-mediated programmed cell death (pyroptosis, apoptosis, necroptosis) is an integral part of host defense against pathogens. Inflammasomes, which are canonically formed upstream of pyroptosis, have been characterized as key mediators of fungal sensing and drivers of proinflammatory responses. However, the specific cell death pathways and key upstream sensors activated in the context of Candida and Aspergillus infections are unknown. Here, we report that C. albicans and A. fumigatus infection induced inflammatory programmed cell death in the form of pyroptosis, apoptosis, and necroptosis (PANoptosis). Further, we identified the innate immune sensor Z-DNA binding protein 1 (ZBP1) as the apical sensor of fungal infection responsible for activating the inflammasome/pyroptosis, apoptosis, and necroptosis. The Zα2 domain of ZBP1 was required to promote this inflammasome activation and PANoptosis. Overall, our results demonstrate that C. albicans and A. fumigatus induce PANoptosis and that ZBP1 plays a vital role in inflammasome activation and PANoptosis in response to fungal pathogens.

Lys234 is one of the residues present in class A β-lactamases that is under selective pressure due to antibiotic use. Located adjacent to proton shuttle residue Ser130, it is suggested to play a role in proton transfer during catalysis of the antibiotics. The mechanism underpinning how substitutions in this position modulate inhibitor efficiency and substrate specificity leading to drug resistance is unclear. The K234R substitution identified in several inhibitor-resistant β-lactamase variants is associated with decreased potency of the inhibitor clavulanic acid, which is used in combination with amoxicillin to overcome β-lactamase–mediated antibiotic resistance. Here we show that for CTX-M-14 β-lactamase, whereas Lys234 is required for hydrolysis of cephalosporins such as cefotaxime, either lysine or arginine is sufficient for hydrolysis of ampicillin. Further, by determining the acylation and deacylation rates for cefotaxime hydrolysis, we show that both rates are fast, and neither is rate-limiting. The K234R substitution causes a 1500-fold decrease in the cefotaxime acylation rate but a 5-fold increase in kcat for ampicillin, suggesting that the K234R enzyme is a good penicillinase but a poor cephalosporinase due to slow acylation. Structural results suggest that the slow acylation by the K234R enzyme is due to a conformational change in Ser130, and this change also leads to decreased inhibition potency of clavulanic acid. Because other inhibitor resistance mutations also act through changes at Ser130 and such changes drastically reduce cephalosporin but not penicillin hydrolysis, we suggest that clavulanic acid paired with an oxyimino-cephalosporin rather than penicillin would impede the evolution of resistance.

This article is by Toni Šušnjar.

Warfare and military are an integral part of much of ancient and medieval fantasy. This is no surprise: warfare was a key element in development of society and of history, and much of mythology is also about it. As such, it is difficult for fantasy writers and readers alike to avoid war and military matters in general. And if you are going to do something, try to do it well. Army does not spring from the ground like the spartoi of Jason.

Environment and Geography

Environmental conditions include terrain, climate and resources. All three influence how an army will fight and which weapons it will use.

Terrain can be highly varied, but I will divide it into three categories: mountainous, rolling hills and flat. Mountains and forests – and especially forested mountains – are conductive to infantry warfare. Depending on other conditions (such as society, climate etc.), this can mean either light infantry with focus on ambushes, raiding and guerilla warfare; or heavy infantry, with focus on direct confrontation. Both of these were, at different points, in evidence in Spain and Greece.

Continue reading Building a Fantasy Army — Environment & Society at Mythic Scribes.

This article is by Toni Šušnjar.

Strategy and Enemies

The structure of an army will depend on the strategy, as strategy will determine the army’s role and tasks. A state which carries out expansion through outright territorial conquest will have large numbers of heavy infantry, combat engineers and artillery, and possibly some heavy cavalry as well (e.g. Roman Empire, 10th century Byzantine Empire). If conquest is done by slowly destroying an opponent’s economic and social structures through constant raiding (such as chevauchee or razzia / ghazw), then majority of the army will be light cavalry, with some heavy cavalry support (e.g. Seljuk and Ottoman Empires), and light infantry will be used if terrain is unsuitable for cavalry. If a state is defending against cavalry raids, then light cavalry will be dominant (e.g. 15th century Hungary), whereas heavy cavalry will predominate if enemy raiders are primarily infantry. If enemy armies are too powerful to face in the field, light and heavy cavalry will be used to harass the invading army and cut off its supplies and foraging. In terrain unsuitable for cavalry operations, heavy infantry will be used instead.

Raiding — as a strategy — is generally preferred against a peer opponent, especially if a state cannot have a developed logistical support system.

Continue reading Building a Fantasy Army — Strategy & Organization at Mythic Scribes.