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.

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 (HS) 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.

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

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 , 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 in is regulated by intracellular reactive sulfur species (RSS), specifically sulfane sulfur.

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 .

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 light–absorbing) and Pfr (far-red light–absorbing). 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 virulence regulator BphP bacteriophytochrome, including two full-length proteins, in the Pr and Pfr states.

Pr-favoured variants of the bacteriophytochrome from the plant pathogen Xanthomonas campestris hint on light regulation of virulence-associated mechanisms.

Red/far-red light-sensing bacteriophytochrome photoreceptor (BphP) pathways play key roles in bacterial physiology and ecology. These bilin-binding proteins photoswitch between two states, Pr (red absorbing) and Pfr (far-red absorbing). The isomerization of the chromophore and the downstream structural changes result in the light signal transduction.

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.

A Spectroscopy-based Methodology for Rapid Screening and Characterization of Phytochrome Photochemistry in Search of Pfr-favored Variants.

Phytochromes are photosensitive proteins with a covalently bound open-chain chromophore that can switch between two principal states: red light absorbing Pr and far-red light absorbing Pfr. Our group has previously shown that the bacteriophytochrome from Xanthomonas campestris pv. campestris (XccBphP) is a bathy-like phytochrome that uses biliverdin IXα as a co-factor and is involved in bacterial virulence.

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 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.