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Biomolecules Apr 2020Spirochetes can be distinguished from other flagellated bacteria by their long, thin, spiral (or wavy) cell bodies and endoflagella that reside within the periplasmic... (Review)
Review
Spirochetes can be distinguished from other flagellated bacteria by their long, thin, spiral (or wavy) cell bodies and endoflagella that reside within the periplasmic space, designated as periplasmic flagella (PFs). Some members of the spirochetes are pathogenic, including the causative agents of syphilis, Lyme disease, swine dysentery, and leptospirosis. Furthermore, their unique morphologies have attracted attention of structural biologists; however, the underlying physics of viscoelasticity-dependent spirochetal motility is a longstanding mystery. Elucidating the molecular basis of spirochetal invasion and interaction with hosts, resulting in the appearance of symptoms or the generation of asymptomatic reservoirs, will lead to a deeper understanding of host-pathogen relationships and the development of antimicrobials. Moreover, the mechanism of propulsion in fluids or on surfaces by the rotation of PFs within the narrow periplasmic space could be a designing base for an autonomously driving micro-robot with high efficiency. This review describes diverse morphology and motility observed among the spirochetes and further summarizes the current knowledge on their mechanisms and relations to pathogenicity, mainly from the standpoint of experimental biophysics.
Topics: Flagella; Movement; Periplasm; Spirochaetales
PubMed: 32260454
DOI: 10.3390/biom10040550 -
Current Opinion in Structural Biology Apr 2021The Ton complex is a molecular motor that uses the proton gradient at the inner membrane of Gram-negative bacteria to apply forces on outer membrane proteins, allowing... (Review)
Review
The Ton complex is a molecular motor that uses the proton gradient at the inner membrane of Gram-negative bacteria to apply forces on outer membrane proteins, allowing active transport of nutrients into the periplasmic space. For decades, contradictory data has been reported on the structure and stoichiometry of the Ton complex. However, recent reports strongly support a subunit stoichiometry of 5:2 for the ExbB-ExbD subcomplex. In this review, we summarize the recent discoveries of the structures and proposed mechanisms of the Ton system, as well as similar protein motor complexes in Gram-negative bacteria.
Topics: Bacterial Proteins; Escherichia coli; Escherichia coli Proteins; Gram-Negative Bacteria; Membrane Proteins; Periplasm
PubMed: 33157479
DOI: 10.1016/j.sbi.2020.09.014 -
Research in Microbiology 2019The CydDC family of ABC transporters export the low molecular weight thiols glutathione and cysteine to the periplasm of a variety of bacterial species. The CydDC... (Review)
Review
The CydDC family of ABC transporters export the low molecular weight thiols glutathione and cysteine to the periplasm of a variety of bacterial species. The CydDC complex has previously been shown to be important for disulfide folding, motility, respiration, and tolerance to nitric oxide and antibiotics. In addition, CydDC is thus far unique amongst ABC transporters in that it binds a haem cofactor that appears to modulate ATPase activity. CydDC has a diverse impact upon bacterial metabolism, growth, and virulence, and is of interest to those working on membrane transport mechanisms, redox biology, aerobic respiration, and stress sensing/tolerance during infection.
Topics: ATP-Binding Cassette Transporters; Adenosine Triphosphatases; Anti-Bacterial Agents; Biological Transport; Cysteine; Escherichia coli; Escherichia coli Proteins; Glutathione; Heme; Oxidation-Reduction; Periplasm
PubMed: 31279084
DOI: 10.1016/j.resmic.2019.06.003 -
International Journal of Molecular... Apr 2023The cell envelope of Gram-negative bacteria contains two distinct membranes, an inner (IM) and an outer (OM) membrane, separated by the periplasm, a hydrophilic...
The cell envelope of Gram-negative bacteria contains two distinct membranes, an inner (IM) and an outer (OM) membrane, separated by the periplasm, a hydrophilic compartment that includes a thin layer of peptidoglycan [...].
Topics: Lipopolysaccharides; Bacterial Outer Membrane Proteins; Cell Membrane; Periplasm; Cell Wall; Peptidoglycan
PubMed: 37108660
DOI: 10.3390/ijms24087498 -
Frontiers in Molecular Biosciences 2021Periplasmic proteins are involved in a wide range of bacterial functions, including motility, biofilm formation, sensing environmental cues, and small-molecule... (Review)
Review
Periplasmic proteins are involved in a wide range of bacterial functions, including motility, biofilm formation, sensing environmental cues, and small-molecule transport. In addition, a wide range of outer membrane proteins and proteins that are secreted into the media must travel through the periplasm to reach their final destinations. Since the porous outer membrane allows for the free diffusion of small molecules, periplasmic proteins and those that travel through this compartment are more vulnerable to external environmental changes, including those that result in protein unfolding, than cytoplasmic proteins are. To enable bacterial survival under various stress conditions, a robust protein quality control system is required in the periplasm. In this review, we focus on several periplasmic chaperones that are stress responsive, including Spy, which responds to envelope-stress, DegP, which responds to temperature to modulate chaperone/protease activity, HdeA and HdeB, which respond to acid stress, and UgpB, which functions as a bile-responsive chaperone.
PubMed: 34046432
DOI: 10.3389/fmolb.2021.678697 -
Microbiology Spectrum May 2019Spirochetes form a separate phylum of bacteria with two membranes but otherwise unusual morphologies and envelope structures. Distinctive common features of , , and...
Spirochetes form a separate phylum of bacteria with two membranes but otherwise unusual morphologies and envelope structures. Distinctive common features of , , and include the sequestration of flagella to the periplasm and thin peptidoglycan cell walls that are more closely associated with the inner membrane. Outer membrane compositions differ significantly between the genera. most closely track Gram-negative bacteria due to the incorporation of lipopolysaccharides. and outer membranes lack lipopolysaccharide, with treponemes expressing only a few outer membrane proteins and displaying a dizzying diversity of abundant surface lipoproteins instead. Phylogenetic and experimental evidence indicates that spirochetes have adapted various modules of bacterial export and secretion pathways to build and maintain their envelopes. Export and insertion pathways in the inner membrane appear conserved, while spirochetal experimentation with various envelope architectures over time has led to variations in secretion pathways in the periplasm and outer membrane. Classical type I to III secretion systems have been identified, with demonstrated roles in drug efflux and export of flagellar proteins only. Unique activities of periplasmic proteases, including a C-terminal protease, are involved in maturation of some periplasmic proteins. Proper lipoprotein sorting within the periplasm appears to be dependent on functional Lol pathways that lack the outer membrane lipoprotein insertase LolB. The abundance of surface lipoproteins in and detailed protein sorting studies suggest a lipoprotein secretion pathway that either extends Lol through the outer membrane or bypasses it altogether. Proteins can be released from cells in outer membrane vesicles or, rarely, as soluble proteins.
Topics: Bacteria; Bacterial Outer Membrane; Bacterial Outer Membrane Proteins; Biological Transport; Cell Membrane; Lipopolysaccharides; Lipoproteins; Periplasm; Phylogeny; Protein Sorting Signals; Protein Transport; Spirochaetales
PubMed: 31198130
DOI: 10.1128/microbiolspec.PSIB-0026-2019 -
Trends in Biochemical Sciences Oct 2016Outer membrane proteins (OMPs) play a central role in the integrity of the outer membrane of Gram-negative bacteria. Unfolded OMPs (uOMPs) transit across the periplasm,... (Review)
Review
Outer membrane proteins (OMPs) play a central role in the integrity of the outer membrane of Gram-negative bacteria. Unfolded OMPs (uOMPs) transit across the periplasm, and subsequent folding and assembly are crucial for biogenesis. Chaperones and the essential β-barrel assembly machinery (BAM) complex facilitate these processes. In vitro studies suggest that some chaperones sequester uOMPs in internal cavities during their periplasmic transit to prevent deleterious aggregation. Upon reaching the outer membrane, the BAM complex acts catalytically to accelerate uOMP folding. Complementary in vivo experiments have revealed the localization and activity of the BAM complex in living cells. Completing an understanding of OMP biogenesis will require a holistic view of the interplay among the individual components discussed here.
Topics: Bacterial Outer Membrane Proteins; Binding Sites; Escherichia coli; Escherichia coli Proteins; Gene Expression; Molecular Chaperones; Molecular Dynamics Simulation; Periplasm; Protein Binding; Protein Conformation, beta-Strand; Protein Folding; Protein Interaction Domains and Motifs; Protein Transport; Protein Unfolding; Thermodynamics
PubMed: 27450425
DOI: 10.1016/j.tibs.2016.06.005 -
Microbiology Spectrum Jul 2019Periplasmic flagella are complex nanomachines responsible for distinctive morphology and motility of spirochetes. Although bacterial flagella have been extensively... (Review)
Review
Periplasmic flagella are complex nanomachines responsible for distinctive morphology and motility of spirochetes. Although bacterial flagella have been extensively studied for several decades in the model systems and , our understanding of periplasmic flagella in many disease-causing spirochetes remains incomplete. Recent advances, including molecular genetics, biochemistry, structural biology, and cryo-electron tomography, have greatly increased our understanding of structure and function of periplasmic flagella. In this chapter, we summarize some of the recent findings that provide new insights into the structure, assembly, and function of periplasmic flagella.
Topics: Bacterial Proteins; Borrelia burgdorferi; Escherichia coli; Flagella; Periplasm; Salmonella enterica
PubMed: 31373267
DOI: 10.1128/microbiolspec.PSIB-0030-2019 -
Applied and Environmental Microbiology Apr 2021Extracellular electron transfer (EET) is an important biological process in microbial physiology as found in dissimilatory metal oxidation/reduction and interspecies... (Review)
Review
Extracellular electron transfer (EET) is an important biological process in microbial physiology as found in dissimilatory metal oxidation/reduction and interspecies electron transfer in syntrophy in natural environments. EET also plays a critical role in microorganisms relevant to environmental biotechnology in metal-contaminated areas, metal corrosion, bioelectrochemical systems, and anaerobic digesters. species exist in a diversity of natural and artificial environments. One of the outstanding features of species is the capability of direct EET with solid electron donors and acceptors, including metals, electrodes, and other cells. Therefore, species are pivotal in environmental biogeochemical cycles and biotechnology applications. , a representative species, has been studied for direct EET as a model microorganism. employs electrically conductive pili (e-pili) and -type cytochromes for the direct EET. The biological function and electronics applications of the e-pili have been reviewed recently, and this review focuses on the cytochromes. species have an unusually large number of cytochromes encoded in their genomes. Unlike most other microorganisms, species localize multiple cytochromes in each subcellular fraction, outer membrane, periplasm, and inner membrane, as well as in the extracellular space, and differentially utilize these cytochromes for EET with various electron donors and acceptors. Some of the cytochromes are functionally redundant. Thus, the EET in is complicated. coordinates the cytochromes with other cellular components in the elaborate EET system to flourish in the environment.
Topics: Bacterial Outer Membrane; Cytochromes; Electron Transport; Geobacter; Intracellular Membranes; Periplasm
PubMed: 33741623
DOI: 10.1128/AEM.03109-20 -
Science Advances Jul 2023Semiconductor-based biointerfaces are typically established either on the surface of the plasma membrane or within the cytoplasm. In Gram-negative bacteria, the...
Semiconductor-based biointerfaces are typically established either on the surface of the plasma membrane or within the cytoplasm. In Gram-negative bacteria, the periplasmic space, characterized by its confinement and the presence of numerous enzymes and peptidoglycans, offers additional opportunities for biomineralization, allowing for nongenetic modulation interfaces. We demonstrate semiconductor nanocluster precipitation containing single- and multiple-metal elements within the periplasm, as observed through various electron- and x-ray-based imaging techniques. The periplasmic semiconductors are metastable and display defect-dominant fluorescent properties. Unexpectedly, the defect-rich (i.e., the low-grade) semiconductor nanoclusters produced in situ can still increase adenosine triphosphate levels and malate production when coupled with photosensitization. We expand the sustainability levels of the biohybrid system to include reducing heavy metals at the primary level, building living bioreactors at the secondary level, and creating semi-artificial photosynthesis at the tertiary level. The biomineralization-enabled periplasmic biohybrids have the potential to serve as defect-tolerant platforms for diverse sustainable applications.
Topics: Periplasm; Biomineralization; Cell Membrane; Cytoplasm; Photosynthesis
PubMed: 37478187
DOI: 10.1126/sciadv.adg5858