scholarly journals Retraction ATPase motors are promiscuous among type IVa pilus systems

2021 ◽  
Author(s):  
Evan Couser ◽  
Jennifer L Chlebek ◽  
Ankur B Dalia
Keyword(s):  
Cell Surface ◽  
Vibrio Cholerae ◽  
Sequence Divergence ◽  
Similar Degree ◽  
Dna Uptake ◽  
Twitching Motility ◽  
Bacterial Surface ◽  
C Terminus ◽  
High Degree ◽  
Surface Dynamic

Bacterial surface appendages called type IVa pili (T4aP) promote diverse activities including DNA uptake, twitching motility, and virulence. These activities rely on the ability of T4aP to dynamically extend and retract from the cell surface. Dynamic extension relies on a motor ATPase commonly called PilB. Most T4aP also rely on specific motor ATPases, commonly called PilT and PilU, to dynamically and forcefully retract. Here, we systematically assess whether motor ATPases from 4 distinct T4aP could functionally complement Vibrio cholerae mutants that lacked their endogenous motors. We found that the retraction ATPases PilT and PilU are highly promiscuous and promote retraction of the V. cholerae competence T4aP despite a high degree of sequence divergence. In contrast, orthologous extension ATPases were not able to mediate extension of the V. cholerae competence T4aP despite a similar degree of sequence divergence. Also, we show that one of the PilT orthologs characterized does not support PilU-dependent retraction and we attributed this loss of activity to the 3' end of the gene, which suggests that the C-terminus of PilT plays an important role in promoting PilU-dependent retraction. Together, our data suggest that retraction ATPases have maintained a high degree of promiscuity for promoting retraction of diverse T4aP, while extension ATPases have evolved to become highly specific for their cognate systems.

Expression of intermediate filament proteins during development of Xenopus laevis. II. Identification and molecular characterization of desmin

Development ◽  
1989 ◽  
Vol 105 (2) ◽  
pp. 299-307 ◽  
Author(s):  
H. Herrmann ◽  
B. Fouquet ◽  
W.W. Franke
Keyword(s):  
Xenopus Laevis ◽  
Time Course ◽  
Mammalian Species ◽  
Sequence Divergence ◽  
Cytoskeletal Proteins ◽  
Similar Degree ◽  
Intermediate Filament Proteins ◽  
Muscle Tissues ◽  
The One ◽  
High Degree

During embryogenesis of avian and mammalian species the formation of intermediate filaments (IFs) containing desmin is characteristic for myogenesis. In view of important differences of patterns of IF protein expression in embryogenic pathways of amphibia on the one hand and birds and mammals on the other, we have decided to study the expression of desmin during early embryogenesis of Xenopus laevis by cDNA hybridization and antibody reactions. Here we describe the isolation of a cDNA clone encoding Xenopus desmin and the deduced amino acid sequence (458 residues; Mr 52,800) which displays a very high degree of conservation during vertebrate evolution from Xenopus to chicken and hamster, with a similar degree of sequence divergence between all three species compared. In addition, we have noted, by both cDNA-hybrid-selection-translation and immunoblotting of cytoskeletal proteins a second desmin-related polypeptide of Mr approximately 49,000. RNA (Northern) blot analyses show the occurrence of three different desmin mRNAs (1.9, 2.6 and 3.0 kb) which seem to represent different polyadenylation sites, displaying quantitative differences in different kinds of muscle tissues. During embryogenesis, desmin mRNA has first been detected in stage-14 embryos and then increases drastically to high levels at stage 18 and thereafter. Immunofluorescence microscopy using desmin-specific antibodies shows that this synthesis of desmin is restricted to somite tissue. The embryonic time course of synthesis of desmin and desmin mRNA is discussed in relation to those of other muscle proteins.

scholarly journals Discovery of Fibrillar Adhesins across Bacterial Species

2020 ◽  
Author(s):  
Vivian Monzon ◽  
Aleix Lafita ◽  
Alex Bateman
Keyword(s):  
Cell Surface ◽  
Bacterial Species ◽  
Domain Architecture ◽  
Surface Proteins ◽  
Host Cells ◽  
Bacterial Surface ◽  
Bacterial Phyla ◽  
C Terminus ◽  
Wide Range ◽  
Bacterial Proteomes

AbstractBackgroundFibrillar adhesins are long multidomain proteins attached at the cell surface and composed of at least one adhesive domain and multiple tandemly repeated domains, which build an elongated stalk that projects the adhesive domain beyond the bacterial cell surface. They are an important yet understudied class of proteins that mediate interactions of bacteria with their environment. This study aims to characterize fibrillar adhesins in a wide range of bacterial phyla and to identify new fibrillar adhesin-like proteins to improve our understanding of host-bacteria interactions.ResultsBy careful search for fibrillar adhesins in the literature and by computational analysis we identified 75 stalk domains and 24 adhesive domains. Based on the presence of these domains in the UniProt Reference Proteomes database, we identified and analysed 3,388 fibrillar adhesin-like proteins across species of the most common bacterial phyla. We found that the bacterial proteomes with the highest fraction of fibrillar adhesins include several known pathogens. We further enumerate the adhesive and stalk domain combinations found in nature and demonstrate that fibrillar adhesins have complex and variable domain architectures, which differ across species. By analysing the domain architecture of fibrillar adhesins we show that in Gram positive bacteria adhesive domains are mostly positioned at the N-terminus of the protein with the cell surface anchor at the C-terminus, while their positions are more variable in Gram negative bacteria. We provide an open repository of fibrillar adhesin-like proteins and domains to facilitate downstream studies of this class of bacterial surface proteins.ConclusionThis study provides a domain-based characterization of fibrillar adhesins and demonstrates that they are widely found across the main bacterial phyla. We have discovered numerous novel fibrillar adhesins and improved the understanding of how pathogens might adhere to and subsequently invade into host cells.

scholarly journals Periscope Proteins are variable length regulators of bacterial cell surface interactions

2020 ◽  
Author(s):  
Fiona Whelan ◽  
Aleix Lafita ◽  
James Gilburt ◽  
Clément Dégut ◽  
Samuel C. Griffiths ◽  
...  
Keyword(s):  
Cell Surface ◽  
Sequence Divergence ◽  
Length Variation ◽  
Human Pathogens ◽  
Sequencing Data ◽  
Bacterial Surface ◽  
New Class ◽  
Long Read ◽  
Surface Alteration ◽  
Cell Surface Interactions

AbstractChanges at the cell surface enable bacteria to survive in dynamic environments, such as diverse niches of the human host. Here, we reveal “Periscope Proteins” as a widespread mechanism of bacterial surface alteration mediated through protein length variation. Tandem arrays of highly similar folded domains can form an elongated rod-like structure; thus variation in the number of domains determines how far an N-terminal host ligand binding domain projects from the cell surface. Supported by newly-available long-read genome sequencing data, we propose this new class could contain over 50 distinct proteins, including those implicated in host colonisation and biofilm formation by human pathogens. In large multi-domain proteins, sequence divergence between adjacent domains appears to reduce inter-domain misfolding. Periscope Proteins break this “rule”, suggesting their length variability plays an important role in regulating bacterial interactions with host surfaces, other bacteria and the immune system.

scholarly journals Discovery of fibrillar adhesins across bacterial species

BMC Genomics ◽  
2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Vivian Monzon ◽  
Aleix Lafita ◽  
Alex Bateman
Keyword(s):  
Cell Surface ◽  
Bacterial Species ◽  
Domain Architecture ◽  
Surface Proteins ◽  
Bacterial Surface ◽  
Bacterial Phyla ◽  
Gram Positive Bacteria ◽  
Invasion Mechanisms ◽  
C Terminus ◽  
Wide Range

Abstract Background Fibrillar adhesins are long multidomain proteins that form filamentous structures at the cell surface of bacteria. They are an important yet understudied class of proteins composed of adhesive and stalk domains that mediate interactions of bacteria with their environment. This study aims to characterize fibrillar adhesins in a wide range of bacterial phyla and to identify new fibrillar adhesin-like proteins to improve our understanding of host-bacteria interactions. Results Through careful literature and computational searches, we identified 82 stalk and 27 adhesive domain families in fibrillar adhesins. Based on the presence of these domains in the UniProt Reference Proteomes database, we identified and analysed 3,542 fibrillar adhesin-like proteins across species of the most common bacterial phyla. We further enumerate the adhesive and stalk domain combinations found in nature and demonstrate that fibrillar adhesins have complex and variable domain architectures, which differ across species. By analysing the domain architecture of fibrillar adhesins, we show that in Gram positive bacteria, adhesive domains are mostly positioned at the N-terminus and cell surface anchors at the C-terminus of the protein, while their positions are more variable in Gram negative bacteria. We provide an open repository of fibrillar adhesin-like proteins and domains to enable further studies of this class of bacterial surface proteins. Conclusion This study provides a domain-based characterization of fibrillar adhesins and demonstrates that they are widely found in species across the main bacterial phyla. We have discovered numerous novel fibrillar adhesins and improved our understanding of pathogenic adhesion and invasion mechanisms.

scholarly journals Periscope Proteins are variable-length regulators of bacterial cell surface interactions

2021 ◽  
Vol 118 (23) ◽  
pp. e2101349118
Author(s):  
Fiona Whelan ◽  
Aleix Lafita ◽  
James Gilburt ◽  
Clément Dégut ◽  
Samuel C. Griffiths ◽  
...  
Keyword(s):  
Cell Surface ◽  
Sequence Divergence ◽  
Length Variation ◽  
Human Pathogens ◽  
Multidomain Proteins ◽  
Sequencing Data ◽  
Bacterial Surface ◽  
Long Read ◽  
Surface Alteration ◽  
Cell Surface Interactions

Changes at the cell surface enable bacteria to survive in dynamic environments, such as diverse niches of the human host. Here, we reveal “Periscope Proteins” as a widespread mechanism of bacterial surface alteration mediated through protein length variation. Tandem arrays of highly similar folded domains can form an elongated rod-like structure; thus, variation in the number of domains determines how far an N-terminal host ligand binding domain projects from the cell surface. Supported by newly available long-read genome sequencing data, we propose that this class could contain over 50 distinct proteins, including those implicated in host colonization and biofilm formation by human pathogens. In large multidomain proteins, sequence divergence between adjacent domains appears to reduce interdomain misfolding. Periscope Proteins break this “rule,” suggesting that their length variability plays an important role in regulating bacterial interactions with host surfaces, other bacteria, and the immune system.

scholarly journals The Unique Structure of Haemophilus influenzae Protein E Reveals Multiple Binding Sites for Host Factors

2012 ◽  
Vol 81 (3) ◽  
pp. 801-814 ◽  
Author(s):  
Birendra Singh ◽  
Tamim Al-Jubair ◽  
Matthias Mörgelin ◽  
Marjolein M. Thunnissen ◽  
Kristian Riesbeck
Keyword(s):  
Haemophilus Influenzae ◽  
Disulfide Bridge ◽  
Lung Epithelial Cells ◽  
Binding Region ◽  
Content Type ◽  
Bacterial Surface ◽  
Hydrogen Bonding Pattern ◽  
Functional Regions ◽  
C Terminus ◽  
Α Helix

ABSTRACTHaemophilus influenzaeprotein E (PE) is a multifunctional adhesin involved in direct interactions with lung epithelial cells and host proteins, including plasminogen and the extracellular matrix proteins vitronectin and laminin. We recently crystallized PE and successfully collected X-ray diffraction data at 1.8 Å. Here, we solved the structure of a recombinant version of PE and analyzed different functional regions. It is a dimer in solution and in the asymmetric unit of the crystals. The dimer has a structure that resembles a flattened β-barrel. It is, however, not a true β-barrel, as there are differences in both the hydrogen-bonding pattern and the shape. Each monomer consisted of a 6-stranded antiparallel β-sheet with a rigid α-helix at the C terminus tethered to the concave side of the sheet by a disulfide bridge. The laminin/plasminogen binding region (residues 41 to 68) is exposed, while the vitronectin binding region (residues 84 to 108) is partially accessible in the dimer. The dimerized PE explains the simultaneous interaction with laminin and vitronectin. In addition, we found this unique adhesin to be present in many bacterial genera of the familyPasteurellaceaeand also orthologues in other, unrelated species (Enterobacter cloacaeandListeria monocytogenes). Peptides corresponding to the surface-exposed regions PE 24 to 37, PE 74 to 89, and PE 134 to 156 were immunogenic in the mouse. Importantly, these peptide-based antibodies also recognized PE at the bacterial surface. Taken together, our detailed structure of PE explains how this important virulence factor ofH. influenzaesimultaneously interacts with host vitronectin, laminin, or plasminogen, promoting bacterial pathogenesis.

Fibrinogen is required for maintenance of platelet intracellular and cell-surface P-selectin expression

Blood ◽  
2009 ◽  
Vol 114 (2) ◽  
pp. 425-436 ◽  
Author(s):  
Hong Yang ◽  
Sean Lang ◽  
Zhimin Zhai ◽  
Ling Li ◽  
Walter H. A. Kahr ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Cell Surface ◽  
Human Fibrinogen ◽  
C Terminus ◽  
Β3 Integrin ◽  
Von Willebrand ◽  
Selectin Binding ◽  
Willebrand Factor ◽  
Deficient Mice ◽  
Granule Release

Abstract Platelet P-selectin plays important roles in inflammation and contributes to thrombosis and hemostasis. Although it has been reported that von Willebrand factor (VWF) affects P-selectin expression on endothelial cells, little information is available regarding regulation of platelet P-selectin expression. Here, we first observed that P-selectin expression was significantly decreased on platelets of fibrinogen and VWF double-deficient mice. Subsequently, we identified this was due to fibrinogen deficiency. Impaired P-selectin expression on fibrinogen-deficient platelets was further confirmed in human hypofibrinogenemic patients. We demonstrated that this impairment is unlikely due to excessive P-selectin shedding, deficient fibrinogen-mediated cell surface P-selectin binding, or impaired platelet granule release, but rather is due to decreased platelet P-selectin content. Fibrinogen transfusion completely recovered this impairment in fibrinogen-deficient (Fg−/−) mice, and engagement of the C-terminus of the fibrinogen γ chain with β3 integrin was required for this process. Furthermore, Fg−/− platelets significantly increased P-selectin expression following transfusion into β3 integrin–deficient mice and when cultured with fibrinogen. These data suggest fibrinogen may play important roles in inflammation, thrombosis, and hemostasis via enhancement of platelet P-selectin expression. Since human fibrinogen levels vary significantly in normal and diseased populations, P-selectin as an activation marker on platelets should be used with caution.

Loss of the C-Terminus of Melanocortin Receptor 2 (MC2R) Results in Impaired Cell Surface Expression and ACTH Insensitivity.

2010 ◽  
pp. OR29-1-OR29-1
Author(s):  
Andrea Hirsch ◽  
Laura Audi ◽  
Eirini Meimaridou ◽  
Adrian J L Clark ◽  
Christa E Fluck
Keyword(s):  
Cell Surface ◽  
Surface Expression ◽  
Melanocortin Receptor ◽  
Cell Surface Expression ◽  
C Terminus ◽  
Acth Insensitivity

scholarly journals The vaccinia virus F12L protein is associated with intracellular enveloped virus particles and is required for their egress to the cell surface

2002 ◽  
Vol 83 (1) ◽  
pp. 195-207 ◽  
Author(s):  
Henriette van Eijl ◽  
Michael Hollinshead ◽  
Gaener Rodger ◽  
Wei-Hong Zhang ◽  
Geoffrey L. Smith
Keyword(s):  
Cell Surface ◽  
Vaccinia Virus ◽  
Virus Particles ◽  
Enveloped Virus ◽  
Virus Morphogenesis ◽  
C Terminus ◽  
Specific Proteins ◽  
Infected Cells ◽  
Mature Virus ◽  
Confocal And Electron Microscopy

The vaccinia virus (VV) F12L gene encodes a 65 kDa protein that is expressed late during infection and is important for plaque formation, EEV production and virulence. Here we have used a recombinant virus (vF12LHA) in which the F12L protein is tagged at the C terminus with an epitope recognized by a monoclonal antibody to determine the location of F12L in infected cells and whether it associates with virions. Using confocal and electron microscopy we show that the F12L protein is located on intracellular enveloped virus (IEV) particles, but is absent from immature virions (IV), intracellular mature virus (IMV) and cell-associated enveloped virus (CEV). In addition, F12L shows co-localization with endosomal compartments and microtubules. F12L did not co-localize with virions attached to actin tails, providing further evidence that actin tails are associated with CEV but not IEV particles. In vΔF12L-infected cells, virus morphogenesis was arrested after the formation of IEV particles, so that the movement of these virions to the cell surface was inhibited and CEV particles were not found. Previously, virus mutants lacking IEV- or EEV-specific proteins were either unable to make IEV particles (vΔF13L and vΔB5R), or were unable to form actin tails after formation of CEV particles (vΔA36R, vΔA33R, vΔA34R). The F12L deletion mutant therefore defines a new stage in the morphogenic pathway and the F12L protein is implicated as necessary for microtubule-mediated egress of IEV particles to the cell surface.

scholarly journals Fresh extension of Vibrio cholerae competence type IV pili predisposes them for motor-independent retraction

2021 ◽  
Author(s):  
Jennifer L. Chlebek ◽  
Triana N. Dalia ◽  
Nicolas Biais ◽  
Ankur B. Dalia
Keyword(s):  
Cell Surface ◽  
Vibrio Cholerae ◽  
Conformational Changes ◽  
Pathogenic Bacteria ◽  
Ectopic Expression ◽  
Type Iv Pili ◽  
Therapeutic Interventions ◽  
Dynamic Activity ◽  
Type Iv ◽  
Additional Support

ABSTRACTBacteria utilize dynamic appendages called type IV pili (T4P) to interact with their environment and mediate a wide variety of functions. Pilus extension is mediated by an extension ATPase motor, commonly called PilB, in all T4P. Pilus retraction, however, can either occur with the aid of an ATPase motor, or in the absence of a retraction motor. While much effort has been devoted to studying motor-dependent retraction, the mechanism and regulation of motor-independent retraction remains poorly characterized. We have previously demonstrated that Vibrio cholerae competence T4P undergo motor-independent retraction in the absence of the dedicated retraction ATPases PilT and PilU. Here, we utilize this model system to characterize the factors that influence motor-independent retraction. We find that freshly extended pili frequently undergo motor-independent retraction, but if these pili fail to retract immediately, they remain statically extended on the cell surface. Importantly, we show that these static pili can still undergo motor-dependent retraction via tightly regulated ectopic expression of PilT, suggesting that these T4P are not broken, but simply cannot undergo motor-independent retraction. Through additional genetic and biophysical characterization of pili, we suggest that pilus filaments undergo conformational changes during dynamic extension and retraction. We propose that only some conformations, like those adopted by freshly extended pili, are capable of undergoing motor-independent retraction. Together, these data highlight the versatile mechanisms that regulate T4P dynamic activity and provide additional support for the long-standing hypothesis that motor-independent retraction occurs via spontaneous depolymerization.SIGNIFICANCEExtracellular pilus fibers are critical to the virulence and persistence of many pathogenic bacteria. A crucial function for most pili is the dynamic ability to extend and retract from the cell surface. Inhibiting this dynamic pilus activity represents an attractive approach for therapeutic interventions, however, a detailed mechanistic understanding of this process is currently lacking. Here, we use the competence pilus of Vibrio cholerae to study how pili retract in the absence of dedicated retraction motors. Our results reveal a novel regulatory mechanism of pilus retraction that is an inherent property of the external pilus filament. Thus, understanding the conformational changes that pili adopt under different conditions may be critical for the development of novel therapeutics that aim to target the dynamic activity of these structures.

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