PcdA promotes orthogonal division plane selection in Staphylococcus aureus.

The bacterial pathogen, Staphylococcus aureus, grows by dividing in two alternating orthogonal planes. How these cell division planes are positioned correctly is not known. Here we used chemical genetic screening to identify PcdA as a division plane placement factor.

Altruistic feeding and cell-cell signaling during bacterial differentiation actively enhance phenotypic heterogeneity.

Starvation triggers bacterial spore formation, a committed differentiation program that transforms a vegetative cell into a dormant spore. Cells in a population enter sporulation nonuniformly to secure against the possibility that favorable growth conditions, which put sporulation-committed cells at a disadvantage, may resume. This heterogeneous behavior is initiated by a passive mechanism: stochastic activation of a master transcriptional regulator.

Bacterial spore surface nanoenvironment requires a AAA+ ATPase to promote MurG function.

spores are produced inside the cytosol of a mother cell. Spore surface assembly requires the SpoVK protein in the mother cell, but its function is unknown. Here, we report that SpoVK is a sporulation-specific, forespore-localized putative chaperone from a distinct higher-order clade of AAA+ ATPases that promotes the peptidoglycan glycosyltransferase activity of MurG during sporulation, even though MurG does not normally require activation during vegetative growth.

A molecular switch controls assembly of bacterial focal adhesions.

Cell motility universally relies on spatial regulation of focal adhesion complexes (FAs) connecting the substrate to cellular motors. In bacterial FAs, the Adventurous gliding motility machinery (Agl-Glt) assembles at the leading cell pole following a Mutual gliding-motility protein (MglA)-guanosine 5'-triphosphate (GTP) gradient along the cell axis. Here, we show that GltJ, a machinery membrane protein, contains cytosolic motifs binding MglA-GTP and AglZ and recruiting the MreB cytoskeleton to initiate movement toward the lagging cell pole.

The phage shock protein (PSP) envelope stress response: discovery of novel partners and evolutionary history.

Bacterial phage shock protein (PSP) systems stabilize the bacterial cell membrane and protect against envelope stress. These systems have been associated with virulence, but despite their critical roles, PSP components are not well characterized outside proteobacteria. Using comparative genomics and protein sequence-structure-function analyses, we systematically identified and analyzed PSP homologs, phyletic patterns, domain architectures, and gene neighborhoods.

The small protein MntS evolved from a signal peptide and acquired a novel function regulating manganese homeostasis in Escherichia coli.

Small proteins (<50 amino acids) are emerging as ubiquitous and important regulators in organisms ranging from bacteria to humans, where they commonly bind to and regulate larger proteins during stress responses. However, fundamental aspects of small proteins, such as their molecular mechanism of action, downregulation after they are no longer needed, and their evolutionary provenance, are poorly understood. Here, we show that the MntS small protein involved in manganese (Mn) homeostasis binds and inhibits the MntP Mn transporter.

Bacterial cell surface nanoenvironment requires a specialized chaperone to activate a peptidoglycan biosynthetic enzyme.

spores are produced inside the cytosol of a mother cell. Spore surface assembly requires the SpoVK protein in the mother cell, but its function is unknown. Here, we report that SpoVK is a dedicated chaperone from a distinct higher-order clade of AAA+ ATPases that activates the peptidoglycan glycosyltransferase MurG during sporulation, even though MurG does not normally require activation by a chaperone during vegetative growth.

The small protein MntS evolved from a signal peptide and acquired a novel function regulating manganese homeostasis in .

Unlabelled: Small proteins (< 50 amino acids) are emerging as ubiquitous and important regulators in organisms ranging from bacteria to humans, where they commonly bind to and regulate larger proteins during stress responses. However, fundamental aspects of small proteins, such as their molecular mechanism of action, downregulation after they are no longer needed, and their evolutionary provenance are poorly understood. Here we show that the MntS small protein involved in manganese (Mn) homeostasis binds and inhibits the MntP Mn transporter.

Apprehending the NAD-ADPr-Dependent Systems in the Virus World.

NAD and ADP-ribose (ADPr)-containing molecules are at the interface of virus-host conflicts across life encompassing RNA processing, restriction, lysogeny/dormancy and functional hijacking. We objectively defined the central components of the NAD-ADPr networks involved in these conflicts and systematically surveyed 21,191 completely sequenced viral proteomes representative of all publicly available branches of the viral world to reconstruct a comprehensive picture of the viral NAD-ADPr systems. These systems have been widely and repeatedly exploited by positive-strand RNA and DNA viruses, especially those with larger genomes and more intricate life-history strategies.

Bacterial developmental checkpoint that directly monitors cell surface morphogenesis.

Bacillus subtilis spores are encased in two concentric shells: an outer proteinaceous "coat" and an inner peptidoglycan "cortex," separated by a membrane. Cortex assembly depends on coat assembly initiation, but how cells achieve this coordination across the membrane is unclear. Here, we report that the protein SpoVID monitors the polymerization state of the coat basement layer via an extension to a functional intracellular LysM domain that arrests sporulation when coat assembly is initiated improperly.

Reformulation of an extant ATPase active site to mimic ancestral GTPase activity reveals a nucleotide base requirement for function.

Hydrolysis of nucleoside triphosphates releases similar amounts of energy. However, ATP hydrolysis is typically used for energy-intensive reactions, whereas GTP hydrolysis typically functions as a switch. SpoIVA is a bacterial cytoskeletal protein that hydrolyzes ATP to polymerize irreversibly during sporulation.

Jumbo Phages: A Comparative Genomic Overview of Core Functions and Adaptions for Biological Conflicts.

Jumbo phages have attracted much attention by virtue of their extraordinary genome size and unusual aspects of biology. By performing a comparative genomics analysis of 224 jumbo phages, we suggest an objective inclusion criterion based on genome size distributions and present a synthetic overview of their manifold adaptations across major biological systems. By means of clustering and principal component analysis of the phyletic patterns of conserved genes, all known jumbo phages can be classified into three higher-order groups, which include both myoviral and siphoviral morphologies indicating multiple independent origins from smaller predecessors.

Antigen Discovery, Bioinformatics and Biological Characterization of Novel Immunodominant Babesia microti Antigens.

Babesia microti is an intraerythrocytic parasite and the primary causative agent of human babesiosis. It is transmitted by Ixodes ticks, transfusion of blood and blood products, organ donation, and perinatally. Despite its global public health impact, limited progress has been made to identify and characterize immunodominant B.

TCRβ-expressing macrophages induced by a pathogenic murine malaria correlate with parasite burden and enhanced phagocytic activity.

Macrophages express a wide array of invariant receptors that facilitate host defense and mediate pathogenesis during pathogen invasion. We report on a novel population of CD11bhighCD14+F4/80+ macrophages that express TCRβ. This population expands dramatically during a Plasmodium berghei ANKA infection and sequesters in the brain during experimental cerebral malaria.

Variations on a theme: evolution of the phage-shock-protein system in Actinobacteria.

The phage shock protein (Psp) stress-response system protects bacteria from envelope stress through a cascade of interactions with other proteins and membrane lipids to stabilize the cell membrane. A key component of this multi-gene system is PspA, an effector protein that is found in diverse bacterial phyla, archaea, cyanobacteria, and chloroplasts. Other members of the Psp system include the cognate partners of PspA that are part of known operons: pspF||pspABC in Proteobacteria, liaIHGFSR in Firmicutes, and clgRpspAMN in Actinobacteria.

Structure-function analysis of manganese exporter proteins across bacteria.

Manganese (Mn) is an essential trace nutrient for organisms because of its role in cofactoring enzymes and providing protection against reactive oxygen species (ROS). Many bacteria require manganese to form pathogenic or symbiotic interactions with eukaryotic host cells. However, excess manganese is toxic, requiring cells to have manganese export mechanisms.

Molecular Markers of Radiation Induced Attenuation in Intrahepatic Plasmodium falciparum Parasites.

Experimental immunization with radiation attenuated sporozoites (RAS) and genetically attenuated sporozoites has proved to be a promising approach for malaria vaccine development. However, parasite biomarkers of growth attenuation and enhanced immune protection in response to radiation remain poorly understood. Here, we report on the effect of an attenuating dose of γ-irradiation (15 krad) on the Plasmodium falciparum sporozoite (PfSPZ) ultrastructure by electron microscopy, growth rate of liver stage P.

The mechanism of force transmission at bacterial focal adhesion complexes.

Various rod-shaped bacteria mysteriously glide on surfaces in the absence of appendages such as flagella or pili. In the deltaproteobacterium Myxococcus xanthus, a putative gliding motility machinery (the Agl-Glt complex) localizes to so-called focal adhesion sites (FASs) that form stationary contact points with the underlying surface. Here we show that the Agl-Glt machinery contains an inner-membrane motor complex that moves intracellularly along a right-handed helical path; when the machinery becomes stationary at FASs, the motor complex powers a left-handed rotation of the cell around its long axis.

Expression, Purification, and Biological Characterization of Babesia microti Apical Membrane Antigen 1.

The intraerythrocytic apicomplexan Babesia microti, the primary causative agent of human babesiosis, is a major public health concern in the United States and elsewhere. Apicomplexans utilize a multiprotein complex that includes a type I membrane protein called apical membrane antigen 1 (AMA1) to invade host cells. We have isolated the full-length B.

The ubiquitous yybP-ykoY riboswitch is a manganese-responsive regulatory element.

The highly structured, cis-encoded RNA elements known as riboswitches modify gene expression upon binding a wide range of molecules. The yybP-ykoY motif was one of the most broadly distributed and numerous bacterial riboswitches for which the cognate ligand was unknown. Using a combination of in vivo reporter and in vitro expression assays, equilibrium dialysis, and northern analysis, we show that the yybP-ykoY motif responds directly to manganese ions in both Escherichia coli and Bacillus subtilis.

CARF and WYL domains: ligand-binding regulators of prokaryotic defense systems.

CRISPR-Cas adaptive immunity systems of bacteria and archaea insert fragments of virus or plasmid DNA as spacer sequences into CRISPR repeat loci. Processed transcripts encompassing these spacers guide the cleavage of the cognate foreign DNA or RNA. Most CRISPR-Cas loci, in addition to recognized cas genes, also include genes that are not directly implicated in spacer acquisition, CRISPR transcript processing or interference.

An autoinhibitory conformation of the Bacillus subtilis spore coat protein SpoIVA prevents its premature ATP-independent aggregation.

Spores of Bacillus subtilis are dormant cell types that are formed when the bacterium encounters starvation conditions. Spores are encased in a shell, termed the coat, which is composed of approximately seventy different proteins and protects the spore's genetic material from environmental insults. The structural component of the basement layer of the coat is an exceptional cytoskeletal protein, termed SpoIVA, which binds and hydrolyzes ATP.

Comprehensive analysis of the HEPN superfamily: identification of novel roles in intra-genomic conflicts, defense, pathogenesis and RNA processing.

Background: The major role of enzymatic toxins that target nucleic acids in biological conflicts at all levels has become increasingly apparent thanks in large part to the advances of comparative genomics. Typically, toxins evolve rapidly hampering the identification of these proteins by sequence analysis. Here we analyze an unexpectedly widespread superfamily of toxin domains most of which possess RNase activity.