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Nature Communications Jun 2024Amongst the major types of archaeal filaments, several have been shown to closely resemble bacterial homologues of the Type IV pili (T4P). Within Sulfolobales, member...
Amongst the major types of archaeal filaments, several have been shown to closely resemble bacterial homologues of the Type IV pili (T4P). Within Sulfolobales, member species encode for three types of T4P, namely the archaellum, the UV-inducible pilus system (Ups) and the archaeal adhesive pilus (Aap). Whereas the archaellum functions primarily in swimming motility, and the Ups in UV-induced cell aggregation and DNA-exchange, the Aap plays an important role in adhesion and twitching motility. Here, we present a cryoEM structure of the Aap of the archaeal model organism Sulfolobus acidocaldarius. We identify the component subunit as AapB and find that while its structure follows the canonical T4P blueprint, it adopts three distinct conformations within the pilus. The tri-conformer Aap structure that we describe challenges our current understanding of pilus structure and sheds new light on the principles of twitching motility.
Topics: Cryoelectron Microscopy; Sulfolobus acidocaldarius; Archaeal Proteins; Fimbriae, Bacterial; Fimbriae Proteins; Models, Molecular
PubMed: 38877033
DOI: 10.1038/s41467-024-45831-w -
Nature Communications Jun 2024Type IV pili are filamentous appendages found in most bacteria and archaea, where they can support functions such as surface adhesion, DNA uptake, aggregation, and...
Type IV pili are filamentous appendages found in most bacteria and archaea, where they can support functions such as surface adhesion, DNA uptake, aggregation, and motility. In most bacteria, PilT-family ATPases disassemble adhesion pili, causing them to rapidly retract and produce twitching motility, important for surface colonization. As archaea do not possess PilT homologs, it was thought that archaeal pili cannot retract and that archaea do not exhibit twitching motility. Here, we use live-cell imaging, automated cell tracking, fluorescence imaging, and genetic manipulation to show that the hyperthermophilic archaeon Sulfolobus acidocaldarius exhibits twitching motility, driven by retractable adhesion (Aap) pili, under physiologically relevant conditions (75 °C, pH 2). Aap pili are thus capable of retraction in the absence of a PilT homolog, suggesting that the ancestral type IV pili in the last universal common ancestor (LUCA) were capable of retraction.
Topics: Sulfolobus acidocaldarius; Fimbriae, Bacterial; Archaeal Proteins; Fimbriae Proteins
PubMed: 38877024
DOI: 10.1038/s41467-024-49101-7 -
Journal of Global Antimicrobial... Jun 2024Streptococcus agalactiae is a recognized pathogen that primarily affects infants and pregnant women. However, its increasingly important role in causing invasive...
BACKGROUND
Streptococcus agalactiae is a recognized pathogen that primarily affects infants and pregnant women. However, its increasingly important role in causing invasive infections among non-pregnant adults has become a significant health concern due to the severity and variety of its clinical impacts.
METHODS
Nonduplicate S. agalactiae clinical strains associated with clinical infections (n=139) were isolated from non-pregnant adults in Shandong, China. Antibiotic susceptibility testing, whole-genome sequencing, and genomic analyses were conducted to characterize the genome and identify resistance features of these strains.
RESULTS
The strains exhibited universal susceptibility to penicillin, ampicillin, cefotaxime, meropenem, linezolid, and vancomycin. Notably, high resistance rates were observed for erythromycin (91.4%), clindamycin (89.2%), levofloxacin (84.2%), tetracycline (54.0%) and, to a lesser extent, chloramphenicol (12.9%). Serotyping revealed seven serotypes and one non-typeable strain. Serotypes Ia, Ib, III, and V predominated, representing 95.7% of the strains. Nineteen sequence types were categorized into seven clonal complexes, with CC10 being the most prevalent at 48.9%. The resistance genes mreA (100%), ermB (70.5%), and tetM (46.0%) were commonly detected. All the isolates carried at least one pilus backbone determinant and one alpha-like protein gene, with the PI-1+PI-2a and the bca gene being the most frequent at 84.2% and 54.7%, respectively.
CONCLUSIONS
While S. agalactiae strains in non-pregnant adults retain sensitivity to β-lactam antibiotics, the elevated resistance to erythromycin, clindamycin, levofloxacin, and tetracycline is concerning. Given the growing elderly population worldwide, the burden of S. agalactiae infections is significant. Continuous surveillance of serotype distribution and antibiotic resistance patterns is imperative for targeted prevention and therapeutic strategies.
PubMed: 38866137
DOI: 10.1016/j.jgar.2024.06.001 -
BioRxiv : the Preprint Server For... May 2024In nature, organisms experience combinations of stressors. However, laboratory studies typically simplify reality and focus on the effects of an individual stressor....
In nature, organisms experience combinations of stressors. However, laboratory studies typically simplify reality and focus on the effects of an individual stressor. Here, we use a microfluidic approach to simultaneously provide a physical stressor (shear flow) and a chemical stressor (H O ) to the human pathogen . By treating cells with levels of flow and H O that commonly co-occur in nature, we discover that previous reports significantly overestimate the H O levels required to block bacterial growth. Specifically, we establish that flow increases H O effectiveness 50-fold, explaining why previous studies lacking flow required much higher concentrations. Using natural H O levels, we identify the core H O regulon, characterize OxyR-mediated dynamic regulation, and dissect the redundant roles of multiple H O scavenging systems. By examining single-cell behavior, we serendipitously discover that the combined effects of H O and flow block pilus-driven surface migration. Thus, our results counter previous studies and reveal that natural levels of H O and flow synergize to restrict bacterial colonization and survival. By studying two stressors at once, our research highlights the limitations of oversimplifying nature and demonstrates that physical and chemical stress can combine to yield unpredictable effects.
PubMed: 38853869
DOI: 10.1101/2024.05.27.595753 -
Gut Microbes 2024Comensal () and are often linked to gut inflammation. However, the causes for variability of pro-inflammatory surface antigens that affect gut commensal/opportunistic...
Comensal () and are often linked to gut inflammation. However, the causes for variability of pro-inflammatory surface antigens that affect gut commensal/opportunistic dualism in remain unclear. By using the classical lipopolysaccharide/O-antigen ' operon' in as a surface antigen model (5-gene-cluster ), and a recent typing strategy for strain classification, we characterized the integrity and conservancy of the entire operon in . Through exploratory analysis of complete genomes and metagenomes, we discovered that most have the operon fragmented into nonrandom patterns of gene-singlets and doublets/triplets, termed 'gene-clusters', or rfb-'minioperons' if predicted as transcriptional. To reflect global operon integrity, contiguity, duplication, and fragmentation principles, we propose a six-category (infra/supra-numerary) cataloging system and a Global Operon Profiling System for bacteria. Mechanistically, genomic sequence analyses revealed that operon fragmentation is driven by intra-operon insertions of predominantly -DNA () and likely natural selection in gut-wall specific micro-niches or micropathologies. -insertions, also detected in other antigenic operons (fimbriae), but not in operons deemed essential (ribosomal), could explain why have fewer KEGG-pathways despite large genomes. DNA insertions, overrepresenting DNA-exchange-avid () species, impact our interpretation of functional metagenomics data by inflating by inflating gene-based pathway inference and by overestimating 'extra-species' abundance. Of disease relevance, species isolated from cavitating/cavernous fistulous tract (CavFT) microlesions in Crohn's Disease have supra-numerary fragmented operons, stimulate TNF-alpha from macrophages with low potency, and do not induce hyperacute peritonitis in mice compared to CavFT . The impact of 'foreign-DNA' insertions on pro-inflammatory operons, metagenomics, and commensalism/opportunism requires further studies to elucidate their potential for novel diagnostics and therapeutics, and to elucidate the role of co-existing pathobionts in Crohn's disease microlesions.
Topics: Operon; Mice; Gastrointestinal Microbiome; Animals; Humans; Metagenomics; Crohn Disease; Bacteroidetes; Antigens, Bacterial; Genome, Bacterial; Enterobacteriaceae
PubMed: 38841888
DOI: 10.1080/19490976.2024.2350150 -
Emerging Microbes & Infections Dec 2024Ceftazidime-avibactam resistance attributable to the gene mutation is increasingly documented in clinical settings. In this study, we characterized the mechanisms...
Ceftazidime-avibactam resistance attributable to the gene mutation is increasingly documented in clinical settings. In this study, we characterized the mechanisms leading to the development of ceftazidime-avibactam resistance in ST11-K47 hypervirulent that harboured the gene. This strain possessed fimbriae and biofilm, demonstrating pathogenicity. Compared with the wild-type KPC-2 carbapenemase, the novel KPC-135 enzyme exhibited a deletion of Glu168 and Leu169 and a 15-amino acid tandem repeat between Val262 and Ala276. The gene was located within the Tn transposon truncated by IS and carried on an IncFII/IncR-type plasmid. Compared to the -positive cloned strain, only the MIC of ceftazidime increased against -positive and wasn't inhibited by avibactam (MIC 32 μg/mL), while clavulanic acid and vaborbactam demonstrated some inhibition. Kinetic parameters revealed that KPC-135 exhibited a lower and cat/ with ceftazidime and carbapenems, and a higher (∼26-fold) 50% inhibitory concentration with avibactam compared to KPC-2. The KPC-135 enzyme exerted a detrimental effect on fitness relative to the wild-type strain. Furthermore, this strain possessed hypervirulent determinants, which included the IncHI1B/FIB plasmid with and expression of type 1 and 3 fimbriae. In conclusion, we reported a novel KPC variant, KPC-135, in a clinical ST11-K47 hypervirulent strain, which conferred ceftazidime-avibactam resistance, possibly through increased ceftazidime affinity and decreased avibactam susceptibility. This strain simultaneously harboured resistance and virulence genes, posing an elevated challenge in clinical treatment.
Topics: Ceftazidime; Klebsiella pneumoniae; Azabicyclo Compounds; Drug Combinations; Anti-Bacterial Agents; Klebsiella Infections; Microbial Sensitivity Tests; beta-Lactamases; Bacterial Proteins; Humans; Virulence; Biofilms; Drug Resistance, Multiple, Bacterial; Plasmids; Animals
PubMed: 38801099
DOI: 10.1080/22221751.2024.2361007 -
Microorganisms May 2024Conjugation of carbohydrates to nanomaterials has been extensively studied and recognized as an alternative in the biomedical field. Dendrimers synthesized with mannose...
Conjugation of carbohydrates to nanomaterials has been extensively studied and recognized as an alternative in the biomedical field. Dendrimers synthesized with mannose at the end group and with entrapped zero-valent copper/silver could be a potential candidate against bacterial proliferation. This study is aimed at investigating the bactericidal activity of metal-glycodendrimers. The Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) reaction was used to synthesize a new mannosylated dendrimer containing 12 mannopyranoside residues in the periphery. The enterotoxigenic fimbriae 4 (ETEC:F4) viability, measured at 600 nm, showed the half-inhibitory concentration (IC) of metal-free glycodendrimers (D), copper-loaded glycodendrimers (D:Cu) and silver-loaded glycodendrimers (D:Ag) closed to 4.5 × 10, 3.5 × 10 and to 1.0 × 10 µg/mL, respectively, and minimum inhibitory concentration (MIC) of D, D:Cu and D:Ag of 2.0, 1.5 and 1.0 × 10 µg/mL, respectively. The release of bacteria contents onto broth and the inhibition of ETEC:F4 biofilm formation increased with the number of metallo-glycodendrimer materials, with a special interest in silver-containing nanomaterial, which had the highest activity, suggesting that glycodendrimer-based materials interfered with bacteria-bacteria or bacteria-polystyrene interactions, with bacteria metabolism and can disrupt bacteria cell walls. Our findings identify metal-mannose-dendrimers as potent bactericidal agents and emphasize the effect of entrapped zero-valent metal against ETEC:F4.
PubMed: 38792795
DOI: 10.3390/microorganisms12050966 -
International Journal of Molecular... May 2024The gene cluster for Type IV pilus (Tfp) biosynthesis is commonly present and highly conserved in . Nevertheless, Tfp-mediated twitching motility is less common among...
The gene cluster for Type IV pilus (Tfp) biosynthesis is commonly present and highly conserved in . Nevertheless, Tfp-mediated twitching motility is less common among strains, and the factors determining twitching activity are not fully understood. Here, we analyzed the functions of three major pilin proteins (PilA1, PilA2, and PilA3) in the assembly and activity of Tfp in motile CGMH010. Using various recombinant deletion strains, we found that Tfp composed of different PilA proteins varied morphologically and functionally. Among the three PilA proteins, PilA1 was most critical in the assembly of twitching-active Tfp, and recombinant strains expressing motility generated more structured biofilms under constant shearing forces compared to the non-motile recombinant strains. Although PilA1 and PilA3 shared 94% identity, PilA3 could not compensate for the loss of PilA1, suggesting that the nature of PilA proteins plays an essential role in twitching activity. The single deletion of individual genes had little effect on the invasion of host endothelia by CGMH010. In contrast, the deletion of all three genes or , encoding the retraction ATPase, abolished Tfp-mediated invasion. Tfp- and PilT-dependent invasion were also detected in the non-motile SK36, and thus, the retraction of Tfp, but not active twitching, was found to be essential for invasion.
Topics: Fimbriae Proteins; Streptococcus sanguis; Fimbriae, Bacterial; Biofilms; Bacterial Proteins
PubMed: 38791440
DOI: 10.3390/ijms25105402 -
Veterinary Sciences May 2024Diarrhea is the most common issue in sheep farms, typically due to pathogenic () infections, such as F17. microRNA, a primary type of non-coding RNA, has been shown to...
Diarrhea is the most common issue in sheep farms, typically due to pathogenic () infections, such as F17. microRNA, a primary type of non-coding RNA, has been shown to be involved in diarrhea caused by pathogenic . To elucidate the profound mechanisms of miRNA in F17 infections, methods such as F17 adhesion assay, colony counting assay, relative quantification of bacterial fimbriae gene expression, indirect immune fluorescence (IF), Cell Counting Kit-8 (CCK-8), 5-ethynyl-2'-deoxyuridine (EdU), Western blotting (WB), and scratch assay were conducted to investigate the effect of miR-329b-5p overexpression/knock-down on F17 susceptibility of sheep intestinal epithelial cells (IECs). The findings indicated that miR-329b-5p enhances the F17 resistance of sheep IECs to F17 by promoting adhesion between F17 and IEC, as well as IEC proliferation and migration. In summary, miR-329b-5p plays a crucial role in the defense of sheep IECs against F17 infection, providing valuable insights into its mechanism of action.
PubMed: 38787178
DOI: 10.3390/vetsci11050206 -
IScience Jun 2024Mechanisms by which () infection enhances oral tumor growth or resistance to cell death remain elusive. Here, we determined that infection mediates therapeutic...
Mechanisms by which () infection enhances oral tumor growth or resistance to cell death remain elusive. Here, we determined that infection mediates therapeutic resistance via inhibiting lethal mitophagy in cancer cells and tumors. Mechanistically, targets the LC3B-ceramide complex by associating with LC3B via bacterial major fimbriae (FimA) protein, preventing ceramide-dependent mitophagy in response to various therapeutic agents. Moreover, ceramide-mediated mitophagy is induced by Annexin A2 (ANXA2)-ceramide association involving the E142 residue of ANXA2. Inhibition of ANXA2-ceramide-LC3B complex formation by wild-type prevented ceramide-dependent mitophagy. Moreover, a FimA-deletion mutant variant had no inhibitory effects on ceramide-dependent mitophagy. Further, 16S rRNA sequencing of oral tumors indicated that infection altered the microbiome of the tumor macroenvironment in response to ceramide analog treatment in mice. Thus, these data provide a mechanism describing the pro-survival roles of in oral tumors.
PubMed: 38779482
DOI: 10.1016/j.isci.2024.109860