The structural basis for high-affinity c-di-GMP binding to the GSPII-B domain of the traffic ATPase PilF from Thermus thermophilus.

c-di-GMP is an important second messenger in bacteria regulating, for example motility, biofilm formation, cell wall biosynthesis, infectivity, and natural transformability. It binds to a multitude of intracellular receptors. This includes proteins containing general secretory pathway II (GSPII) domains such as the N-terminal domain of the Vibrio cholerae ATPase MshE (MshEN) which binds c-di-GMP with two copies of a 24-amino acids sequence motif.

Identification of subcomplexes and protein-protein interactions in the DNA transporter of Thermus thermophilus HB27.

The natural transformation system of the thermophilic bacterium Thermus thermophilus comprises at least 16 competence proteins. Recently we found that the outer membrane (OM) competence protein PilW interacts with the secretin channel, which guides type IV pili (T4P) and potential DNA transporter pseudopili through the OM. Here we have used biochemical techniques to study the interactions of cytoplasmic, inner membrane (IM) and OM components of the DNA transporter in T.

A concept for international societally relevant microbiology education and microbiology knowledge promulgation in society.

Executive Summary: Microbes are all pervasive in their distribution and influence on the functioning and well-being of humans, life in general and the planet. Microbially-based technologies contribute hugely to the supply of important goods and services we depend upon, such as the provision of food, medicines and clean water. They also offer mechanisms and strategies to mitigate and solve a wide range of problems and crises facing humanity at all levels, including those encapsulated in the sustainable development goals (SDGs) formulated by the United Nations.

Wax Ester and Triacylglycerol Production in : Role in Osmostress Protection, Reactive Oxygen Species, and Antibiotic Sensitivity.

Wax esters (WEs) are neutral lipids that are produced by many different bacteria as potential carbon and energy storage compounds. Comparatively little is known about the role of WE in pathogenic bacteria. The opportunistic pathogen is a major cause of hospital-acquired infections worldwide.

A temperature dependent pilin promoter for production of thermostable enzymes in Thermus thermophilus.

Background: Enzymes from thermophiles are of great interest for research and bioengineering due to their stability and efficiency. Thermophilic expression hosts such as Thermus thermophilus [T. thermophilus] can overcome specific challenges experienced with protein production in mesophilic expression hosts, such as leading to better folding, increased protein stability, solubility, and enzymatic activity.

Identification and characterization of a novel pathway for aldopentose degradation in Acinetobacter baumannii.

The nosocomial pathogen Acinetobacter baumannii is well known for its extraordinary metabolic diversity. Recently, we demonstrated growth on L-arabinose, but the pathway remained elusive. Transcriptome analyses revealed two upregulated gene clusters that code for isoenzymes catalysing oxidation of a pentonate to α-ketoglutarate.

K homeostasis is important for survival of Acinetobacter baumannii ATCC 19606 in the nosocomial environment.

Pathogenic bacteria have developed several mechanisms to thrive within the hostile environment of the human host, but it is often disregarded that their survival outside this niche is crucial for their successful transmission. Acinetobacter baumannii is very well adapted to both the human host and the hospital environment. The latter is facilitated by multifactorial mechanisms including its outstanding ability to survive on dry surfaces, its high metabolic diversity, and, of course, its remarkable osmotic resistance.

The Tol-Pal system of Acinetobacter baumannii is important for cell morphology, antibiotic resistance and virulence.

Acinetobacter baumannii is an opportunistic human pathogen that has become a global threat to healthcare institutions. This Gram-negative bacterium is one of the most successful human pathogens worldwide and responsible for hospital-acquired infections. This is due to its outstanding potential to adapt to very different environments, to persist in the human host and most important, its ability to develop multidrug resistance.

Evolutionarily stable gene clusters shed light on the common grounds of pathogenicity in the Acinetobacter calcoaceticus-baumannii complex.

Nosocomial pathogens of the Acinetobacter calcoaceticus-baumannii (ACB) complex are a cautionary example for the world-wide spread of multi- and pan-drug resistant bacteria. Aiding the urgent demand for novel therapeutic targets, comparative genomics studies between pathogens and their apathogenic relatives shed light on the genetic basis of human-pathogen interaction. Yet, existing studies are limited in taxonomic scope, sensing of the phylogenetic signal, and resolution by largely analyzing genes independent of their organization in functional gene clusters.

The carnitine degradation pathway of Acinetobacter baumannii and its role in virulence.

The opportunistic human pathogen Acinetobacter baumannii can grow with carnitine but its metabolism, regulation and role in virulence remained elusive. Recently, we identified a carnitine transporter encoded by a gene closely associated with potential carnitine degradation genes. Among those is a gene coding for a putative d-malate dehydrogenase (Mdh).

The ß-ketoadipate pathway of Acinetobacter baumannii is involved in complement resistance and affects resistance against aromatic antibiotics.

Acinetobacter baumannii can thrive on a broad range of substrates such as sugars, alcohols, lipids, amino acids and aromatic compounds. The latter three are abundant in the human host and are potential candidates as carbon sources for the metabolic adaptation of A. baumannii to the human host.

DNA binding by pilins and their interaction with the inner membrane platform of the DNA transporter in Thermus thermophilus.

The natural transformation system of Thermus thermophilus has become a model system for studies of the structure and function of DNA transporter in thermophilic bacteria. The DNA transporter in T. thermophilus is functionally linked to type IV pili (T4P) and the major pilin PilA4 plays an essential role in both systems.

CsrA Coordinates Compatible Solute Synthesis in Acinetobacter baumannii and Facilitates Growth in Human Urine.

CsrA is a global regulator widespread in bacteria and known to be involved in different physiological processes, including pathogenicity. Deletion of of Acinetobacter baumannii strain ATCC 19606 resulted in a mutant that was unable to utilize a broad range of carbon and energy sources, including amino acids. This defect in amino acid metabolism was most likely responsible for the growth inhibition of the Δ mutant in human urine, where amino acids are the most abundant carbon source for A.

Natural transformation in Gram-negative bacteria thriving in extreme environments: from genes and genomes to proteins, structures and regulation.

Extremophilic prokaryotes live under harsh environmental conditions which require far-reaching cellular adaptations. The acquisition of novel genetic information via natural transformation plays an important role in bacterial adaptation. This mode of DNA transfer permits the transfer of genetic information between microorganisms of distant evolutionary lineages and even between members of different domains.

The choline dehydrogenase BetA of Acinetobacter baumannii: a flavoprotein responsible for osmotic stress protection.

Acinetobacter baumannii is outstanding for its ability to cope with low water activities which significantly contributes to its persistence in hospital environments. The vast majority of bacteria are able to prevent loss of cellular water by amassing osmoactive compatible solutes or their precursors into the cytoplasm. One such precursor of an osmoprotectant is choline that is taken up from the environment and oxidized to the compatible solute glycine betaine.

K and its role in virulence of Acinetobacter baumannii.

Acinetobacter baumannii is an opportunistic human pathogen that has become a global threat to healthcare institutions worldwide. The success of A. baumannii is based on the rise of multiple antibiotic resistances and its outstanding potential to persist in the human host and under conditions of low water activity in hospital environments.

Functional dissection of structural regions of the Thermus thermophilus competence protein PilW: Implication in secretin complex stability, natural transformation and pilus functions.

Uptake of DNA from the environment into the bacterial cytoplasm is mediated by a macromolecular transport machinery that is similar in structure and function to type IV pili (T4P) and, indeed, DNA translocator and T4P share common components. One is the secretin PilQ which is assembled into homopolymeric complexes forming highly dynamic outer membrane (OM) channels mediating pilus extrusion and DNA uptake. How PilQ interacts with the motor is still enigmatic.

In vivo synthesis of monolysocardiolipin and cardiolipin by Acinetobacter baumannii phospholipase D and effect on cationic antimicrobial peptide resistance.

Acinetobacter baumannii is an opportunistic pathogen, which has become a rising threat in healthcare facilities worldwide due to increasing antibiotic resistances and optimal adaptation to clinical environments and the human host. We reported in a former publication on the identification of three phopholipases of the phospholipase D (PLD) superfamily in A. baumannii ATCC 19606 acting in concerted manner as virulence factors in Galleria mellonella infection and lung epithelial cell invasion.

Trehalose-6-phosphate-mediated phenotypic change in Acinetobacter baumannii.

The stress protectant trehalose is synthesized in Acinetobacter baumannii from UPD-glucose and glucose-6-phosphase via the OtsA/OtsB pathway. Previous studies proved that deletion of otsB led to a decreased virulence, the inability to grow at 45°C and a slight reduction of growth at high salinities indicating that trehalose is the cause of these phenotypes. We have questioned this conclusion by producing ∆otsA and ∆otsBA mutants and studying their phenotypes.

A first response to osmostress in Acinetobacter baumannii: transient accumulation of K and its replacement by compatible solutes.

The extraordinary desiccation resistance of the opportunistic human pathogen Acinetobacter baumannii is a key to its survival and spread in medical care units. The accumulation of compatible solute such as glutamate, mannitol and trehalose contributes to the desiccation resistance. Here, we have used osmolarity as a tool to study the response of cells to low water activities and studied the role of a potential inorganic osmolyte, K , in osmostress response.

Cryo-electron microscopy reveals two distinct type IV pili assembled by the same bacterium.

Type IV pili are flexible filaments on the surface of bacteria, consisting of a helical assembly of pilin proteins. They are involved in bacterial motility (twitching), surface adhesion, biofilm formation and DNA uptake (natural transformation). Here, we use cryo-electron microscopy and mass spectrometry to show that the bacterium Thermus thermophilus produces two forms of type IV pilus ('wide' and 'narrow'), differing in structure and protein composition.

Identification of osmo-dependent and osmo-independent betaine-choline-carnitine transporters in Acinetobacter baumannii: role in osmostress protection and metabolic adaptation.

Acinetobacter baumannii is outstanding for its ability to cope with low water activities and therefore its adaptation mechanism to osmotic stress. Here we report on the identification and characterization of five different secondary active compatible solute transporters, belonging to the betaine-choline-carnitine transporter (BCCT) family. Our studies revealed two choline-specific and three glycine betaine-specific BCCTs.

NMR resonance assignments for the GSPII-B domain of the traffic ATPase PilF from Thermus thermophilus in the apo and the c-di-GMP-bound state.

The PilF protein from the thermophilic bacterium Thermus thermophilus is a traffic ATPase powering the assembly of the DNA translocation machinery as well as of type 4 pili. Thereby PilF mediates the natural transformability of T. thermophilus.