Kai Thormann

• Prof. Dr.
• Professor at University of Giessen

The coordination of cell cycle progression and flagellar synthesis is a complex process in motile bacteria. In γ-proteobacteria, the localization of the flagellum to the cell pole is mediated by the SRP-type GTPase FlhF. However, the mechanism of action of FlhF, and its relationship with the cell pole landmark protein HubP remain unclear. In this s...

The coordination of cell cycle progression and flagellar synthesis is a complex process in motile bacteria. In γ-proteobacteria, the localization of the flagellum to the cell pole is mediated by the SRP-type GTPase FlhF. However, the mechanism of action of FlhF, and its relationship with the cell pole landmark protein HubP remain unclear. In this s...

The basal structure of the bacterial flagellum includes a membrane embedded MS-ring (formed by multiple copies of FliF) and a cytoplasmic C-ring (composed of proteins FliG, FliM and FliN). The SRP-type GTPase FlhF is required for directing the initial flagellar protein FliF to the cell pole, but the mechanisms are unclear. Here, we show that FlhF a...

Phage-induced lysis of Gram-negative bacterial hosts usually requires a set of phage lysis proteins, a holin, an endopeptidase, and a spanin system, to disrupt each of the three cell envelope layers. Genome annotations and previous studies identified a gene region in the Shewanella oneidensis prophage LambdaSo, which comprises potential holin- and...

Bacterial viruses (phages) are potent agents of lateral gene transfer and thus are important drivers of evolution. A group of mobile genetic elements, referred to as phage satellites, exploits phages to disseminate their own genetic material. Here, we isolated a novel member of the family Inoviridae, Shewanella phage Dolos, along with an autonomous...

The SRP-type GTPase FlhF, along with its regulator FlhG, orchestrates the localization and quantity of flagella in bacteria. Our study reveals that FlhF anchors developing flagellar structures to the polar landmark protein HubP/FimV, thereby restricting their formation to the cell pole. Specifically, the GTPase domain of FlhF interacts with HubP, w...

Co-evolution of bacterial defense systems and phage counter defense mechanisms has resulted in an intricate biological interplay between bacteriophages and their prey. To evade nuclease-based mechanisms targeting the DNA, various bacteriophages modify their nucleobases, which impedes or even inhibits recognition by endonucleases. We found that Shew...

Phage-induced lysis of Gram-negative bacterial hosts usually requires a set of phage lysis proteins, a holin, an endopeptidase and a spanin system, to disrupt each of the three cell envelope layers. Genome annotations and previous studies identified a gene region in the Shewanella oneidensis prophage LambdaSo, which comprises potential holin- and e...

The coordination of cell cycle progression and flagellar synthesis is a complex process in motile bacteria. In γ-proteobacteria, the localization of the flagellum to the cell pole is mediated by the SRP-type GTPase FlhF. However, the mechanism of action of FlhF, and its relationship with the cell pole landmark protein HubP remain unclear. In this s...

The coordination of cell cycle progression and flagellar synthesis is a complex process in motile bacteria. In γ-proteobacteria, the localization of the flagellum to the cell pole is mediated by the SRP-type GTPase FlhF. However, the mechanism of action of FlhF, and its relationship with the cell pole landmark protein HubP remain unclear. In this s...

Bacterial viruses (phages) are potent agents of lateral gene transfer and thus are important drivers of evolution. A group of mobile genetic elements (MGEs), referred to as phage satellites, exploit phages to disseminate their own genetic material. Here we isolated a novel member of the genus Inovirus , Shewanella phage Dolos, along with an autonom...

Background: The number of periprosthetic joint infections caused by vancomycin-resistant pathogens is increasing. Currently, no PMMA cement is commercially available to cover VRE. Daptomycin shows promising results in treating infection, offering a good safety profile and a reduced risk of developing resistance. The purpose of this in vitro study...

Small heat shock proteins (sHSPs) represent a first line of stress defense in many bacteria. The primary function of these molecular chaperones involves preventing irreversible protein denaturation and aggregation. In Escherichia coli, fibrillar EcIbpA binds unfolded proteins and keeps them in a folding-competent state. Further, its structural homo...

Background: Number of joint infections caused by Vancomycin-resistant pathogens is emerging. Currently no PMMA cement is commercially available to cover VRE. Daptomycin shows promising results in infection treatment, offers a good safety profile and reduced risk for resistance development. Purpose of this in vitro study is to investigate the mechan...

The coordination of cell cycle progression and flagellar synthesis is a complex process in motile bacteria. In gamma-proteobacteria, the localization of the flagellum to the cell pole is mediated by the SRP-type GTPase FlhF. However, the mechanism of action of FlhF, and its relationship with the cell pole landmark protein HubP remain unclear. In th...

Multicellular behavior benefits seemingly simple organisms such as bacteria, by improving nutrient uptake, resistance to stresses, or by providing advantages in predatory interactions. Several recent studies have shown that this also extends to the defense against bacteriophages, which are omnipresent in almost all habitats. In this review, we summ...

The bacterial cell pole has long been recognized as a defined compartment for enzymatic activities that are important or even vital for the cell. Polarity of diguanylate cyclases and phosphodiesterases, enzymes that synthesize and degrade the second messenger c-di-GMP, has now been demonstrated for several bacterial systems. Here we review these po...

Multicellular behaviour benefits seemingly simple organisms such as bacteria, by improving nutrient uptake, resistance to stresses or by providing advantages in predatory interactions. Several recent studies have shown that this also extends to the defense against bacteriophages, which are omnipresent in almost all habitats. In this review, we summ...

In bacteria, the monopolar localization of enzymes and protein complexes can result in a bimodal distribution of enzyme activity between the dividing cells and heterogeneity of cellular behaviors. In Shewanella putrefaciens , the multidomain hybrid diguanylate cyclase/phosphodiesterase PdeB, which degrades the secondary messenger c-di-GMP, is locat...

Flagella are multiprotein complexes whose assembly and positioning requires complex spatiotemporal control. Flagellar assembly is thought to be controlled by several transcriptional tiers, which is mediated through various master regulators. Here, we revisited the regulation of flagellar genes in polarly flagellated gammaproteobacteria by the regul...

Flagella are multiprotein complexes whose assembly and positioning requires complex spatiotemporal control. Flagellar assembly is thought to be controlled by several transcriptional tiers, which is mediated through various master regulators. Here, we revisited the regulation of flagellar genes in polarly flagellated gammaproteobacteria by the regul...

A huge number of bacterial species are motile by flagella, which allow them to actively move toward favorable environments and away from hazardous areas and to conquer new habitats. The general perception of flagellum-mediated movement and chemotaxis is dominated by the Escherichia coli paradigm, with its peritrichous flagellation and its famous ru...

Flagella enable bacteria to actively spread within the environment. A number of species possess two separate flagellar systems, where in most cases a primary polar flagellar system is supported by distinct secondary lateral flagella under appropriate conditions. Using functional fluorescence tagging on one of these species, Shewanella putrefaciens,...

The search for novel drugs that efficiently eliminate prokaryotic pathogens is one of the most urgent health topics of our time. Robust evaluation methods for monitoring the antibiotic stress response in prokaryotes are therefore necessary for developing respective screening strategies. Besides advantages of common in vitro techniques, there is a g...

Flagellar motors are intricate rotating nanomachines that are powered by transmembrane ion gradients. The stator complexes are the powerhouses of the flagellar motor: They convert a transmembrane ion gradient, mainly of H+ or Na+, into rotation of the helical flagellar filament. They are thus essential for motor function. The number of stators sync...

The search for novel drugs that efficiently eliminate prokaryotic pathogens is one of the most urgent health topics of our time. Robust evaluation methods for monitoring the antibiotic stress response in prokaryotes are therefore necessary for developing respective screening strategies. Besides advantages of common in vitro techniques, there is a g...

Bacteria frequently engage in obligate metabolic mutualisms with other microorganisms. However, it remains generally unclear how the resulting metabolic dependencies affect the ecological niche space accessible to the whole consortium relative to the niche space available to its constituent individuals. Here we address this issue by systematically...

In bacteria, the monopolar localization of enzymes and protein complexes can result in a bi-modal distribution of enzyme activity between the dividing cells and heterogeneity of cellular behaviors. In Shewanella putrefaciens , the multidomain hybrid diguanylate cyclase/phosphodiesterase PdeB, which degrades the secondary messenger c-di-GMP, is loca...

[This corrects the article DOI: 10.3389/fmicb.2021.668892.].

A number of bacterial species control the function of the flagellar motor in response to the levels of the secondary messenger c-di-GMP, which is often mediated by c-di-GMP-binding proteins that act as molecular brakes or clutches to slow the motor rotation. The gammaproteobacterium Shewanella putrefaciens possesses two distinct flagellar systems,...

We have studied the localization and dynamics of bacterial Ffh, part of the SRP complex, its receptor FtsY, and of ribosomes in the Gamma-proteobacterium Shewanella putrefaciens. Using structured illumination microscopy, we show that ribosomes show a pronounced accumulation at the cell poles, whereas SRP and FtsY are distributed at distinct sites a...

The search for novel drugs that efficiently eliminate prokaryotic pathogens is one of the most urgent health topics of our time. Robust evaluation methods for monitoring the antibiotic stress response in prokaryotes are therefore necessary for developing respective screening strategies. Besides advantages of common in vitro techniques, there is a g...

Flagella are bacterial organelles of locomotion. Their biogenesis is highly coordinated in time and space and relies on a specialized flagellar type III secretion system (fT3SS) required for the assembly of the extracellular hook, rod, and filament parts of this complex motor device. The fT3SS protein FlhB switches secretion substrate specificity o...

Bacteria frequently engage in obligate metabolic mutualisms with other microorganisms. However, it remains generally unclear how the resulting metabolic dependencies affect the ecological niche space accessible to the whole consortium relative to the niche space available to its constituent individuals. Here we address this issue by systematically...

Species of the genus Shewanella are widespread in nature in various habitats, however, little is known about phages affecting Shewanella sp. Here, we report the isolation of phages from diverse freshwater environments that infect and lyse strains of Shewanella oneidensis and other Shewanella sp. Sequence analysis and microscopic imaging strongly in...

Significance Flagella, bacterial organelles of locomotion, appear in a defined number and localization at the bacterial cell surface. The MinD-type ATPase FlhG numerically regulates flagellation patterns through a molecular mechanism only poorly understood. Depending on its ATP-dependent oligomerization state, FlhG interacts either with the C-ring...

Flagella-mediated motility, where propulsion is mediated by a rotating helical filament, is a very widespread and effective means of locomotion for numerous bacteria. Almost half of all species assemble their filament from more than one distinct building block, the flagellin. Here we show how bacteria may use different flagellins to build a filamen...

Bacterial cells in nature are frequently exposed to changes in their chemical environment1,2. The response mechanisms of isolated cells to such stimuli have been investigated in great detail. By contrast, little is known about the emergent multicellular responses to environmental changes, such as antibiotic exposure3,4,5,6,7, which may hold the key...

Biofilms form when bacteria aggregate in a self-secreted exopolysaccharide matrix. Biofilms are resistant to antibiotics and thus implicated in human disease. Nitric oxide (NO) is known to mediate biofilm formation in many bacteria via ligation to H-NOX (heme-NO/oxygen binding) proteins. Most NO-responsive bacteria, however, lack H-NOX domain-conta...

Polysaccharide intercellular adhesin (PIA)‐associated biofilm formation is mediated by the intercellular adhesin (ica) locus and represents a major pathomechanism of Staphylococcus epidermidis. Here we report on a novel long non‐coding (nc)RNA, named IcaZ, which is approximately 400 nucleotides in size. icaZ is located downstream of the ica repress...

Bacteria switch only intermittently to motile planktonic lifestyles under favorable conditions. Under chronic nutrient deprivation, however, bacteria orchestrate a switch to stationary phase, conserving energy by altering metabolism and stopping motility. About two-thirds of bacteria use flagella to swim, but how bacteria deactivate this large mole...

Lysed P. shigelloides cells show multiple flagellar relics at the pole. (A) Slice through a tomogram with red arrows highlighting relic structures. (B) A different slice from the same tomogram as shown in (A) showing the top view of more relic structures. (TIFF)

Relic structures are made of the same proteins as flagellar motors and can be visualised by negative-stain EM. (A) Example particles extracted from negative-stain EM images of relic structures isolated using affinity purification of a S. putrefaciens MotX-His strain. (B) Example 2D class average of relic structures showing concentric rings. (C) Sli...

Analysis of subtomogram averages. FSC curves of subtomogram averages and subtomogram averages of the P. shigelloides motor (top panel) and relic structure (bottom panel) before and after applying symmetry. Resolution at a 0.5 threshold of the unsymmetrized motor structure is approximately 3.3 nm, and the unsymmetrized relic is approximately 4.7 nm....

Flagellar filaments are not required for flagellar ejection. (A) Slice through a tomogram of P. shigelloides ΔfliC showing intact motors with hooks but no filament. (B) Slice through a tomogram of P. shigelloides ΔfliC showing multiple relics (red arrows). (TIFF)

Underlying data for Figs 1A, 1C, 1D, 3F, 4A, 4B, 5A, 5B, 5C, 5D, 5E and 5H. (XLSX)

Partial flagellar motors are relics of old motors and are not formed in mutants incapable of assembling rods. Slices through six representative tomograms of ΔflhA cells. No relics were seen at the poles of any of the 68 cells imaged. Red arrows indicate chemoreceptor arrays. (TIFF)

Placement of motors and relics in 3D. The 3D placement of relics and full flagellar motors on the pole of a representative cell. Red arrows point to relics, green flagellar filaments indicate full motors. (TIFF)

c-di-GMP-dependent signaling affects a range of processes in many bacterial species. Most bacteria harbor a plethora of proteins with domains which are potentially involved in synthesis and breakdown of c-di-GMP. A potential mechanism to elicit an appropriate c-di-GMP-dependent response is to organize the corresponding proteins in a spatiotemporal...

Bacterial flagella are helical proteinaceous fibers, composed of the protein flagellin, that confer motility to many bacterial species. The genomes of about half of all flagellated species include more than one flagellin gene, for reasons mostly unknown. Here we show that two flagellins (FlaA and FlaB) are spatially arranged in the polar flagellum...

Bacterial extracellular nucleases have multiple functions in processes as diverse as nutrient acquisition, natural transformation, biofilm formation, or defense against neutrophil extracellular traps (NETs). Here we explored the properties of ExeM in Shewanella oneidensis MR-1, an extracellular nuclease, which is widely conserved among species of S...

Bacteria switch only intermittently to motile planktonic lifestyles under favourable conditions. Under chronic nutrient deprivation, however, bacteria orchestrate a switch to stationary phase, conserving energy by altering metabolism and stopping motility. About two-thirds of bacteria use flagella to swim, but how bacteria deactivate this large-mol...

The ability of most bacterial flagellar motors to reverse the direction of rotation is crucial for efficient chemotaxis. In Escherichia coli, motor reversals are mediated by binding of phosphorylated chemotaxis protein CheY to components of the flagellar rotor, FliM and FliN, which induces a conformational switch of the flagellar C‐ring. Here we sh...

Bacteria swim in sequences of straight runs that are interrupted by turning events. They drive their swimming locomotion with the help of rotating helical flagella. Depending on the number of flagella and their arrangement across the cell body, different run-and-turn patterns can be observed. Here, we present fluorescence microscopy recordings show...

Significance It has long been established that flagella provide an efficient means of movement for bacteria in planktonic environments (free swimming) or across surfaces (swarming). However, rather little is known about bacterial motility in structured environments. In this study, we demonstrate that polarly flagellated bacteria can exploit a polym...

The stator is an eminent component of the flagellar motor and determines a number of the motor’s properties, such as the rotation-energizing coupling ion (H+ or Na+) or the torque that can be generated. The stator consists of several units located in the cytoplasmic membrane surrounding the flagellar drive shaft. Studies on flagellar motors of seve...

Shewanella oneidensis MR-1 possesses two different stator units to drive flagellar rotation, the Na+-dependent PomAB stator and the H+-driven MotAB stator, the latter possibly acquired by lateral gene transfer. Although either stator can independently drive swimming through liquid, MotAB-driven motors cannot support efficient motility in structured...

Type I CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats)–Cas (CRISPR-associated) systems exist in bacterial and archaeal organisms and provide immunity against foreign DNA. The Cas protein content of the DNA interference complexes (termed Cascade) varies between different CRISPR-Cas subtypes. A minimal variant of the Type I-F syste...

Spatiotemporal regulation of cell polarity plays a role in many fundamental processes in bacteria and often relies on 'landmark' proteins which recruit the corresponding clients to their designated position. Here, we explored the localization of two multi-protein complexes, the polar flagellar motor and the chemotaxis array, in Shewanella putrefaci...

Bacteria differ in number and location of their flagella that appear in regular patterns at the cell surface (flagellation pattern). Despite the plethora of bacterial species, only a handful of these patterns exist. The correct flagellation pattern is a prerequisite for motility, but also relates to biofilm formation and the pathogenicity of diseas...

The bacterial flagellar motor is an intricate nanomachine which converts ion gradients into rotational movement. Torque is created by ion-dependent stator complexes which surround the rotor in a ring. Shewanella oneidensis MR-1 expresses two distinct types of stator unit: the Na(+) -dependent PomA4 B2 and the H(+) -dependent MotA4 B2 . Here, we hav...

Significance Flagella are bacterial organelles of locomotion. The number and location of flagella (flagellation pattern) are species specific and represent one of the earliest taxonomic criteria in microbiology. During each round of cell division, bacteria reproduce their flagellation pattern. FlhG is essential to a variety of flagellation patterns...

Bacteriophages and genetic elements, such as prophage-like elements, pathogenicity islands, and phage morons, make up a considerable amount of the bacterial genome. Their transfer and subsequent activity within the host's genetic circuitry have had a significant impact on bacterial evolution. In what follows, it is considered what underlying mechan...

Significance Flagella-mediated motility is an important or even crucial propagation factor for many bacteria. A number of polarly flagellated species possess a distinct secondary flagellar system, which, as current models suggest, allows more effective swimming under conditions of elevated viscosity or across surfaces. In this study, we demonstrate...

Prophages are ubiquitous elements within bacterial chromosomes and affect host physiology and ecology in multiple ways. We have previously demonstrated that phage-induced lysis is required for extracellular DNA (eDNA) release and normal biofilm formation in Shewanella oneidensis MR-1. Here, we investigated the regulatory mechanisms of prophage λSo...

Shewanella oneidensis is a bacterium that is sometimes referred to as Shewanella oneidensis “MR-1”, indicating the “manganese reducing” capability of this organism. Species of the genus Shewanella belong to the group of facultatively anaerobic gammaproteobacteria, which exhibit a pronounced respiratory flexibility that allows them to use a wide ran...

Neisseria gonorrhoeae is an obligate human pathogen, which colonizes the genital tract and causes gonorrhea. N. gonorrhoeae can form biofilms during natural cervical infections, on glass and in continuous flow-chamber systems. These biofilms contain large amounts of extracellular DNA, which plays an important role in biofilm formation. Many clinica...

The unsheathed flagellar filament of Shewanella oneidensis MR-1 is composed of two highly homologous flagellins, FlaA, and the major structural unit, FlaB. We identified a gene cluster, SO_3261-SO_3265 (now sfmABCDE), that is required for the formation of a fully functional filament and for motility. The predicted function of the corresponding gene...

In all species of the genus Shewanella, the redox-sensing Arc two-component system consists of the response regulator ArcA, the sensor kinase ArcS, and the separate phosphotransfer protein HptA. Compared to its counterpart ArcB in Escherichia coli, ArcS has a significantly different domain structure. Resequencing and reannotation revealed that in t...

Bacterial biofilm formation starts with single cells attaching to a surface, however, little is known about the initial attachment steps and the adaptation to the surface-associated life style. Here, we describe a hydrodynamic system that allows easy harvest of cells at very early biofilm stages. Using the metal ion-reducing gammaproteobacterium Sh...

Bacterial species such as Shewanella oneidensis MR-1 require extracellular nucleolytic activity for the utilization of extracellular DNA (eDNA) as a source of nutrients and for the turnover of eDNA as a structural matrix component during biofilm formation. We have previously characterized two extracellular nucleases of S. oneidensis MR-1, ExeM and...

The bacterial flagellar motor is a highly dynamic multiprotein complex. A number of species takes advantage of this by actively swapping components to adjust motor function according to the environmental conditions. Here we describe how such bacterial flagellar “motor tuning” might occur.