Flagella and bacterial pathogenicity

Duan, Qiangde; Zhu, Liqian; Zhu, Guoqiang

doi:10.1002/jobm.201100335

Cited by 341 publications

(242 citation statements)

References 69 publications

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“…8), all of the flagella-related genes were preferentially expressed during early infection, with high expression 6 hpi. This would support the idea that flagellin might trigger the activation of immune responses in the host to attract macrophages and initiate productive infection (Steiner et al 2000, McCarthy et al 2008, Rojas et al 2009, Duan et al 2013, Rozas & Enriquez 2014.…”

Section: Discussionsupporting

confidence: 67%

Expression of flagellin and key regulatory flagellar genes in the non-motile bacterium Piscirickettsia salmonis

Carril

Gómez²,

Marshall³

2017

Dis. Aquat. Org.

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The Piscirickettsia salmonis genome was screened to evaluate potential flagellarelated open reading frames, as well as their genomic organization and eventual expression. A complete and organized set of flagellar genes was found for P. salmonis, although no structural flagellum has ever been reported for this bacterium. To gain further understanding, the hierarchical flagellar cascade described for Legionella pneumophila was used as a reference model for putative analysis in P. salmonis. Specifically, 5 of the most relevant genes from this cascade were chosen, including 3 regulatory genes (fleQ, triggers the cascade; fliA, regulates the σ28-coding gene; and rpoN, an RNA polymerase-dependent gene) and 2 terminal structural genes (flaA and flaB, flagellin and a flagellin-like protein, respectively). Kinetic experiments evaluated gene expressions over time, with P. salmonis assessed in 2 liquid, cell-free media and during infection of the SHK-1 fish cell line. Under all conditions, the 5 target genes were primarily expressed during early growth/infection and were differentially expressed when bacteria encountered environmental stress (i.e. a high-salt concentration). Intriguingly, the flagellin monomer was fully expressed under all growth conditions and was located near the bacterial membrane. While no structural flagellum was detected under any condition, the recombinant flagellin monomer induced a proinflammatory response in SHK-1 cells, suggesting a possible immunomodulatory function. The potential implications of these observations are discussed in the context of P. salmonis biology and pathogenic potential.

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Section: Discussionsupporting

confidence: 67%

Expression of flagellin and key regulatory flagellar genes in the non-motile bacterium Piscirickettsia salmonis

Carril

Gómez²,

Marshall³

2017

Dis. Aquat. Org.

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“…Motility and biofilm are two virulence-associated phenotypes relevant to bacterial pathogenicity in vivo (28). Since DksA was shown to be involved in these phenotypes in other pathogen (15), we were interested in characterizing the possible role of DksA in Salmonella motility and biofilm formation.…”

Section: Resultsmentioning

confidence: 99%

The Stringent Response Regulator DksA Is Required for Salmonella enterica Serovar Typhimurium Growth in Minimal Medium, Motility, Biofilm Formation, and Intestinal Colonization

et al. 2016

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c Salmonella enterica serovar Typhimurium is a facultative intracellular human and animal bacterial pathogen posing a major threat to public health worldwide. Salmonella pathogenicity requires complex coordination of multiple physiological and virulence pathways. DksA is a conserved Gram-negative regulator that belongs to a distinct group of transcription factors that bind directly to the RNA polymerase secondary channel, potentiating the effect of the signaling molecule ppGpp during a stringent response. Here, we established that in S. Typhimurium, dksA is induced during the logarithmic phase and DksA is essential for growth in minimal defined medium and plays an important role in motility and biofilm formation. Furthermore, we determined that DksA positively regulates the Salmonella pathogenicity island 1 and motility-chemotaxis genes and is necessary for S. Typhimurium invasion of human epithelial cells and uptake by macrophages. In contrast, DksA was found to be dispensable for S. Typhimurium host cell adhesion. Finally, using the colitis mouse model, we found that dksA is spatially induced at the midcecum during the early stage of the infection and required for gastrointestinal colonization and systemic infection in vivo. Taken together, these data indicate that the ancestral stringent response regulator DksA coordinates various physiological and virulence S. Typhimurium programs and therefore is a key virulence regulator of Salmonella. Salmonella enterica is a facultative intracellular human and animal bacterial pathogen responsible for global pandemics of food-borne infections that pose a major threat to public health. This highly versatile pathogen can infect a broad range of hosts and causes different clinical outcomes, ranging from asymptomatic carriage to systemic life-threatening disease (1). The single species S. enterica includes more than 2,600 serovars that share high sequence similarity and are taxonomically classified into six subspecies (2). Estimations suggest that Salmonella causes 93.8 million human infections and 155,000 deaths annually worldwide (3). The majority of nontyphoidal Salmonella (NTS) infections in humans present as gastroenteritis; however, about 5% may be invasive and manifest as bacteremia or other extraintestinal infections (4). Many of the NTS serovars are capable of colonizing the intestines of livestock with potential risk of contaminating the food chain, and therefore, salmonellosis is often associated with animal products and produce (5). One of the most common serovars worldwide is S. enterica serovar Typhimurium, ranking first in prevalence in North America and Oceania (6).Salmonella intestinal colonization is a complex phenotype essential for establishing disease. Salmonella colonization requires synchronized function of both conserved and host-specific colonization factors such as fimbrial adhesins, invasion factors (e.g., SiiE, MisL, and ShdA) and genes encoded within Salmonella pathogenicity island 1 (SPI-1) and SPI-2 (reviewed in references 7 and 8). Both SPIs e...

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“…Several studies have reported that flagella are necessary for biofilm formation by E. coli and other bacteria such as Listeria monocytogenes and Yersinia enterocolitica (22,34,35). Furthermore, in addition to the presence of flagellar filaments, motor proteins that cause flagellar rotation are required.…”

Section: Discussionmentioning

confidence: 99%

Bacterial flagella explore microscale hummocks and hollows to increase adhesion

Friedlander

Vlamakis

Kim

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

269

238

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Biofilms, surface-bound communities of microbes, are economically and medically important due to their pathogenic and obstructive properties. Among the numerous strategies to prevent bacterial adhesion and subsequent biofilm formation, surface topography was recently proposed as a highly nonspecific method that does not rely on small-molecule antibacterial compounds, which promote resistance. Here, we provide a detailed investigation of how the introduction of submicrometer crevices to a surface affects attachment of Escherichia coli. These crevices reduce substrate surface area available to the cell body but increase overall surface area. We have found that, during the first 2 h, adhesion to topographic surfaces is significantly reduced compared with flat controls, but this behavior abruptly reverses to significantly increased adhesion at longer exposures. We show that this reversal coincides with bacterially induced wetting transitions and that flagellar filaments aid in adhesion to these wetted topographic surfaces. We demonstrate that flagella are able to reach into crevices, access additional surface area, and produce a dense, fibrous network. Mutants lacking flagella show comparatively reduced adhesion. By varying substrate crevice sizes, we determine the conditions under which having flagella is most advantageous for adhesion. These findings strongly indicate that, in addition to their role in swimming motility, flagella are involved in attachment and can furthermore act as structural elements, enabling bacteria to overcome unfavorable surface topographies. This work contributes insights for the future design of antifouling surfaces and for improved understanding of bacterial behavior in native, structured environments. microbial adhesion | structured surfaces | bacterial appendages | surface texture | surface wetting T he attachment of bacteria to solid surfaces is the first step in the formation of biofilms-communities of sessile microbes surrounded by a polymeric matrix (1, 2). A growing appreciation of the ubiquity and importance of biofilms in medicine and industry has led to a proliferation of antiadhesion strategies that include chemical, biological, and physical approaches (3-12). Attempts to block biofilm formation must also take into account the rapid evolution of bacteria and their ability to resist many chemical assaults (13)(14)(15)(16)(17). By preventing adhesion in a manner that is nontoxic for the bacteria as well as for the application (e.g., medical implants), there is hope that we may reduce the costs associated with biofilm formation without imposing selective pressures for the development of antibiotic resistance. Physical strategies, particularly the use of rationally designed surface topographies, have gained attention recently as highly nonspecific methods for prevention of attachment without the use of antimicrobials (6,8,11,(18)(19)(20).Understanding how bacteria interact with surfaces that have roughness on the micrometer and submicrometer length scales (i.e., comparable with th...

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Flagella and bacterial pathogenicity

Cited by 341 publications

References 69 publications

Expression of flagellin and key regulatory flagellar genes in the non-motile bacterium Piscirickettsia salmonis

Expression of flagellin and key regulatory flagellar genes in the non-motile bacterium Piscirickettsia salmonis

The Stringent Response Regulator DksA Is Required for Salmonella enterica Serovar Typhimurium Growth in Minimal Medium, Motility, Biofilm Formation, and Intestinal Colonization

Bacterial flagella explore microscale hummocks and hollows to increase adhesion

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