Increased intracellular persulfide levels attenuate HlyU-mediated hemolysin transcriptional activation in Vibrio cholerae.

The vertebrate host's immune system and resident commensal bacteria deploy a range of highly reactive small molecules that provide a barrier against infections by microbial pathogens. Gut pathogens, such as Vibrio cholerae, sense and respond to these stressors by modulating the expression of exotoxins that are crucial for colonization. Here, we employ mass spectrometry-based profiling, metabolomics, expression assays, and biophysical approaches to show that transcriptional activation of the hemolysin gene hlyA in V. cholerae is regulated by intracellular forms of sulfur with sulfur-sulfur bonds, termed reactive sulfur species (RSS). We first present a comprehensive sequence similarity network analysis of the arsenic repressor superfamily of transcriptional regulators, where RSS and hydrogen peroxide sensors segregate into distinct clusters of sequences. We show that HlyU, transcriptional activator of hlyA in V. cholerae, belongs to the RSS-sensing cluster and readily reacts with organic persulfides, showing no reactivity or DNA dissociation following treatment with glutathione disulfide or hydrogen peroxide. Surprisingly, in V. cholerae cell cultures, both sulfide and peroxide treatment downregulate HlyU-dependent transcriptional activation of hlyA. However, RSS metabolite profiling shows that both sulfide and peroxide treatment raise the endogenous inorganic sulfide and disulfide levels to a similar extent, accounting for this crosstalk, and confirming that V. cholerae attenuates HlyU-mediated activation of hlyA in a specific response to intracellular RSS. These findings provide new evidence that gut pathogens may harness RSS-sensing as an evolutionary adaptation that allows them to overcome the gut inflammatory response by modulating the expression of exotoxins.

Sensing and regulation of reactive sulfur species (RSS) in bacteria.

The infected host deploys generalized oxidative stress caused by small inorganic reactive molecules as antibacterial weapons. An emerging consensus is that hydrogen sulfide (H2S) and forms of sulfur with sulfur-sulfur bonds termed reactive sulfur species (RSS) provide protection against oxidative stressors and antibiotics, as antioxidants. Here, we review our current understanding of RSS chemistry and its impact on bacterial physiology. We start by describing the basic chemistry of these reactive species and the experimental approaches developed to detect them in cells. We highlight the role of thiol persulfides in H2S-signaling and discuss three structural classes of ubiquitous RSS sensors that tightly regulate cellular H2S/RSS levels in bacteria, with a specific focus on the chemical specificity of these sensors.

Polysulfide metabolizing enzymes influence SqrR-mediated sulfide-induced transcription by impacting intracellular polysulfide dynamics.

Sulfide plays essential roles in controlling various physiological activities in almost all organisms. Although recent evidence has demonstrated that sulfide is endogenously generated and metabolized into polysulfides inside the cells, the relationship between polysulfide metabolism and polysulfide-sensing mechanisms is not well understood. To better define this interplay between polysulfide metabolism and sensing in cells, we investigated the role of polysulfide-metabolizing enzymes such as sulfide:quinone oxidoreductase (SQR) on the temporal dynamics of cellular polysulfide speciation and on the transcriptional regulation by the persulfide-responsive transcription factor SqrR in Rhodobacter capsulatus. We show that disruption of the sqr gene resulted in the loss of SqrR repression by exogenous sulfide at longer culture times, which impacts the speciation of intracellular polysulfides of Δsqr vs. wild-type strains. Both the attenuated response of SqrR and the change in polysulfide dynamics of the Δsqr strain is fully reversed by the addition to cells of cystine-derived polysulfides, but not by glutathione disulfide (GSSG)-derived polysulfides. Furthermore, cysteine persulfide (CysSSH) yields a higher rate of oxidation of SqrR relative to glutathione persulfide (GSSH), which leads to DNA dissociation in vitro. The oxidation of SqrR was confirmed by a mass spectrometry-based kinetic profiling strategy that showed distinct polysulfide-crosslinked products obtained with CysSSH vs. GSSH. Taken together, these results establish a novel association between the metabolism of polysulfides and the mechanisms for polysulfide sensing inside the cells.

Increased intracellular persulfide levels attenuate HlyU-mediated hemolysin transcriptional activation in Vibrio cholerae.

The vertebrate host’s immune system and resident commensal bacteria deploy a range of highly reactive small molecules that provide a barrier against infections by microbial pathogens. Gut pathogens, such as Vibrio cholerae , sense and respond to these stressors by modulating the expression of exotoxins that are crucial for colonization. Here, we employ mass-spectrometry-based profiling, metabolomics, expression assays and biophysical approaches to show that transcriptional activation of the hemolysin gene hlyA in V. cholerae is regulated by intracellular reactive sulfur species (RSS), specifically sulfane sulfur. We first present a comprehensive sequence similarity network analysis of the arsenic repressor (ArsR) superfamily of transcriptional regulators where RSS and reactive oxygen species (ROS) sensors segregate into distinct clusters. We show that HlyU, transcriptional activator of hlyA in V. cholerae , belongs to the RSS-sensing cluster and readily reacts with organic persulfides, showing no reactivity and remaining DNA-bound following treatment with various ROS in vitro, including H 2 O 2 . Surprisingly, in V. cholerae cell cultures, both sulfide and peroxide treatment downregulate HlyU-dependent transcriptional activation of hlyA . However, RSS metabolite profiling shows that both sulfide and peroxide treatment raise the endogenous inorganic sulfide and disulfide levels to a similar extent, accounting for this crosstalk, and confirming that V. cholerae attenuates HlyU-mediated activation of hlyA in a specific response to intracellular RSS. These findings provide new evidence that gut pathogens may harness RSS-sensing as an evolutionary adaptation that allows them to overcome the gut inflammatory response by modulating the expression of exotoxins.

Structural basis for the Pr-Pfr long-range signaling mechanism of a full-length bacterial phytochrome at the atomic level.

Phytochromes constitute a widespread photoreceptor family that typically interconverts between two photostates called Pr (red light­absorbing) and Pfr (far-red light­absorbing). The lack of full-length structures solved at the (near-)atomic level in both pure Pr and Pfr states leaves gaps in the structural mechanisms involved in the signal transmission pathways during the photoconversion. Here, we present the crystallographic structures of three versions from the plant pathogen Xanthomonas campestris virulence regulator XccBphP bacteriophytochrome, including two full-length proteins, in the Pr and Pfr states. The structures show a reorganization of the interaction networks within and around the chromophore-binding pocket, an α-helix/ß-sheet tongue transition, and specific domain reorientations, along with interchanging kinks and breaks at the helical spine as a result of the photoswitching, which subsequently affect the quaternary assembly. These structural findings, combined with multidisciplinary studies, allow us to describe the signaling mechanism of a full-length bacterial phytochrome at the atomic level.

Molecular Evolution of Transition Metal Bioavailability at the Host-Pathogen Interface.

The molecular evolution of the adaptive response at the host-pathogen interface has been frequently referred to as an 'arms race' between the host and bacterial pathogens. The innate immune system employs multiple strategies to starve microbes of metals. Pathogens, in turn, develop successful strategies to maintain access to bioavailable metal ions under conditions of extreme restriction of transition metals, or nutritional immunity. However, the processes by which evolution repurposes or re-engineers host and pathogen proteins to perform or refine new functions have been explored only recently. Here we review the molecular evolution of several human metalloproteins charged with restricting bacterial access to transition metals. These include the transition metal-chelating S100 proteins, natural resistance-associated macrophage protein-1 (NRAMP-1), transferrin, lactoferrin, and heme-binding proteins. We examine their coevolution with bacterial transition metal acquisition systems, involving siderophores and membrane-spanning metal importers, and the biological specificity of allosteric transcriptional regulatory proteins tasked with maintaining bacterial metallostasis. We also discuss the evolution of metallo-ß-lactamases; this illustrates how rapid antibiotic-mediated evolution of a zinc metalloenzyme obligatorily occurs in the context of host-imposed nutritional immunity.

The impact of an exercise program on quality of life in older breast cancer survivors undergoing aromatase inhibitor therapy: a randomized controlled trial.

BACKGROUND: This study evaluated the impact of an exercise program on quality of life in older breast cancer survivors undergoing aromatase inhibitor therapy. METHODS: Older breast cancer survivors were randomized into two groups: combined training: resistance + aerobic exercise program for nine months (n = 18) or control group (n = 18). Quality of life was assessed by the questionnaires SF36, EORTC QLQ-C30, and EORTC QLQ-BR23 at baseline, and at three, six, and nine months. The exercise group performed 40 min of resistance exercises on machines followed by 30 min of aerobic training on a treadmill 3x/wk. Repeated measures ANOVA was used to compare the groups over time. RESULTS: Significant time x group interactions and moderate to high effect sizes were found for physical functioning, physical health, bodily pain, general health perception, vitality, social functioning, fatigue, sleep disturbance, body image, and upset by hair loss, favoring the exercise group. CONCLUSION: This study demonstrated the potential benefits and high clinical relevance of exercise programs to improve quality of life in older breast cancer survivors undergoing aromatase inhibitor therapy.

Draft Genome Sequence of Methylobacterium sp. Strain V23, Isolated from Accretion Ice of the Antarctic Subglacial Lake Vostok.

Here, we report the draft genome sequence of Methylobacterium sp. strain V23, a bacterium isolated from accretion ice of the subglacial Lake Vostok (3,592 meters below the surface). This genome makes possible the study of ancient and psychrophilic genes and proteins from a subglacial environment isolated from the surface for at least 15 million years.

Partial remission of refractory RA after Adacolumn cytapheresis: a case report.

We report on a female case of rheumatoid arthritis (RA) with hepatitis C virus comorbidity. The patient was treated once weekly over ten consecutive weeks with Adacolumn device. Clinical assessment and HCV-RNA concentration were monitored at weeks-1, 4, 9, 14 and during follow-up over 6 months. At the end of the treatment: the number of tender and swollen joints, patient's global assessment of disease activity (VAS), physician's VAS, C-reactive protein (CRP) decreased, respectively; ACR response was >20. This improvement was maintained for over 2 months. At week 38, the patient was re-treated achieving again an ACR response >20.

Cytokine patterns in fibromyalgia and their correlation with clinical manifestations.

OBJECTIVE: To examine the possible role of the soluble factor in fibromyalgia (FM) by studying the correlation of cytokine levels with the patients' clinical and psychiatric profile. METHODS: Eighty FM patients underwent clinical and psychiatric evaluations, and plasma levels of cytokines (IL-1, IL-6, IL-8, IL-10, TNF-alpha), aspecific markers of inflammation, rheumatoid factor (RF), anti-extractable nuclear antigen (ENA) antibodies, and anti-nuclear factor (FAN) were measured. RESULTS: Higher levels of IL-10, IL-8 and TNF-alpha were found in FM patients than in controls. Significant correlations between the biochemical parameters and clinical data were found. CONCLUSION: The higher levels of cytokines found in FM patients suggest the presence of an inflammatory response system (IRS) and highlight a parallel between the clinical symptoms and biochemical data. They support the hypothesis that cytokines may play a role in the clinical features of fibromyalgia. In addition, the similar cytokine patterns found in FM patients with different psychiatric profiles suggests that IRS impairment may play a specific role in the disease.

Peripheral benzodiazepine receptors on platelets of fibromyalgic patients.

OBJECTIVE: The aim of the present study was to analyze if alterations of peripheral-type benzodiazepine receptor (PBR) characteristics occurred in platelet membranes of patients affected by primary fibromyalgia (FM). DESIGN AND METHODS: Platelets were obtained from 30 patients with FM. Evaluation of kinetic parameters of PBR was performed using [(3)H] PK11195 as specific radioligand compared with 16 healthy volunteers. RESULTS: The results showed a significant increase of PBR binding sites value in platelet membranes from FM patients (B(max) was 5366+/-188 fmol/mg vs. controls, 4193+/-341 fmol/mg, mean+/-SEM) (**p<0.01) but not for affinity value (K(d) was 4.90+/-0.39 nM vs. controls, 4.74+/-0.39 nM, mean+/-SEM) (p>0.05). Symptom severity scores (pain and tiredness) were positively correlated with B(max). CONCLUSIONS: Our results showed an up-regulation of PBR in platelets of FM patients, and this seems to be related to the severity of fibromyalgic symptoms.

On sending artifact in search of artifact: reply to Mcdonald, Harris, and Maher.

Two studies are reported that show the McDonald, Harris, and Maher critique of our earlier experiment to be mistaken. In the first study, arousal-induced attention to self was demonstrated in a field setting devoid of any of the artifactual covariates of arousal induction suggested by these researchers. In the second study, a replication of the McDonald et al. experiment was conducted in which a crucial manipulation check that they failed to make was included. This check on the unusualness and embarrassment-producing properties of the manipulations revealed that their study was burdened by the very artifact they claimed might exist in ours. Although their slow-running manipulation was superficially similar to our fast-running manipulation, slow running created self-focus through unusualness and embarrassment, whereas fast running led to self-focus via arousal.