scholarly journals Proteolytic Processing of the Mycoplasma hyopneumoniae Cilium Adhesin

2004 ◽  
Vol 72 (5) ◽  
pp. 2791-2802 ◽  
Author(s):  
Steven P. Djordjevic ◽  
Stuart J. Cordwell ◽  
Michael A. Djordjevic ◽  
Jody Wilton ◽  
F. Chris Minion
Keyword(s):  
Signal Sequence ◽  
Surface Protein ◽  
Mycoplasma Hyopneumoniae ◽  
Proteolytic Processing ◽  
Secreted Proteins ◽  
Immunogold Electron Microscopy ◽  
Swine Pathogen ◽  
C Terminus ◽  
J Proteins ◽  
Ciliated Epithelial Cells

ABSTRACT Mycoplasma hyopneumoniae is an economically significant swine pathogen that colonizes the respiratory ciliated epithelial cells. Cilium adherence is mediated by P97, a surface protein containing a repeating element (R1) that is responsible for binding. Here, we show that the cilium adhesin is proteolytically processed on the surface. Proteomic analysis of strain J proteins identified cleavage products of 22, 28, 66, and 94 kDa. N-terminal sequencing showed that the 66- and 94-kDa proteins possessed identical N termini and that the 66-kDa variant was generated by cleavage of the 28-kDa product from the C terminus. The 22-kDa product represented the N-terminal 195 amino acids of the cilium adhesin preprotein, confirming that the hydrophobic leader signal sequence is not cleaved during translocation across the membrane. Comparative studies of M. hyopneumoniae strain 232 showed that the major cleavage products of the cilium adhesin are similar, although P22 and P28 appear to be processed further in strain 232. Immunoblotting studies using antisera raised against peptide sequences within P22 and P66/P94 indicate that processing is complex, with cleavage occurring at different frequencies within multiple sites, and is strain specific. Immunogold electron microscopy showed that fragments containing the cilium-binding site remained associated with the cell surface whereas cleavage products not containing the R1 element were located elsewhere. Not all secreted proteins undergo multiple cleavage, however, as evidenced by the analysis of the P102 gene product. The ability of M. hyopneumoniae to selectively cleave its secreted proteins provides this pathogen with a remarkable capacity to alter its surface architecture.

scholarly journals Streptococcus mutans Murein Hydrolase

2005 ◽  
Vol 187 (22) ◽  
pp. 7863-7865 ◽  
Author(s):  
Diana M. Catt ◽  
Richard L. Gregory
Keyword(s):  
Amino Acid ◽  
Streptococcus Mutans ◽  
Signal Sequence ◽  
Surface Protein ◽  
Open Reading Frame ◽  
Direct Repeats ◽  
Reading Frame ◽  
Allelic Replacement ◽  
C Terminus ◽  
Murein Hydrolase

ABSTRACT Allelic replacement of the C terminus of a Streptococcus mutans surface protein affects murein hydrolase activity. The targeted open reading frame encodes a 67-kDa protein (SmaA) with an N-terminal signal sequence and cleavage site, three 46-amino-acid (aa) direct repeats, and two 88-aa direct repeats. The identical autolytic profile was obtained using a sortase mutant (SrtA−).

scholarly journals Two Domains within the Mycoplasma hyopneumoniae Cilium Adhesin Bind Heparin

2006 ◽  
Vol 74 (1) ◽  
pp. 481-487 ◽  
Author(s):  
Cheryl Jenkins ◽  
Jody L. Wilton ◽  
F. Chris Minion ◽  
Linda Falconer ◽  
Mark J. Walker ◽  
...  
Keyword(s):  
Amino Acids ◽  
Pathogenic Bacteria ◽  
Mycoplasma Hyopneumoniae ◽  
Binding Activity ◽  
Sulfated Polysaccharides ◽  
Heparin Binding ◽  
Swine Production ◽  
C Terminus ◽  
Respiratory Cilia ◽  
Ciliated Epithelial Cells

ABSTRACT Mycoplasma hyopneumoniae is the causative agent of porcine enzootic pneumonia, a chronic and economically significant respiratory disease that affects swine production worldwide. M. hyopneumoniae adheres to and adversely affects the function of ciliated epithelial cells of the respiratory tract, and the cilium adhesin (Mhp183, P97) is intricately but not exclusively involved in this process. Although binding of pathogenic bacteria to glycosaminoglycans is a recognized step in pathogenesis, knowledge of glycosaminoglycan-binding proteins in M. hyopneumoniae is lacking. However, heparin and other sulfated polysaccharides are known to block the binding of M. hyopneumoniae to purified swine respiratory cilia. In this study, four regions within the cilium adhesin were examined for the ability to bind heparin. Cilium adhesin fragments comprising 653 amino acids of the N terminus and 301 amino acids of the C terminus (containing two repeat regions, R1 and R2) were cloned and expressed. These fragments bound heparin in a dose-dependent and saturable manner with physiologically significant binding affinities of 0.27 ± 0.02 μM and 1.89 ± 0.33 μM, respectively. Heparin binding of both fragments was strongly inhibited by the sulfated polysaccharides fucoidan and mucin but not by chondroitin sulfate B. When the C-terminal repeat regions R1 and R2 were cloned separately and expressed, heparin-binding activity was lost, suggesting that both regions are required for heparin binding. The ability of the cilium adhesin to bind heparin indicates that this molecule plays a multifunctional role in the adherence of M. hyopneumoniae to host respiratory surfaces and therefore has important implications with respect to the pathogenesis of this organism.

scholarly journals Molecular Analysis of Group B Protective Surface Protein, a New Cell Surface Protective Antigen of Group B Streptococci

2002 ◽  
Vol 70 (2) ◽  
pp. 803-811 ◽  
Author(s):  
Sezgin Erdogan ◽  
Peter K. Fagan ◽  
Susanne R. Talay ◽  
Manfred Rohde ◽  
Patricia Ferrieri ◽  
...  
Keyword(s):  
Protective Antigen ◽  
Signal Sequence ◽  
Virulent Strain ◽  
Lethal Dose ◽  
Surface Protein ◽  
Surface Proteins ◽  
Immunogold Electron Microscopy ◽  
Specific Response ◽  
Group B Streptococci ◽  
Group B

ABSTRACT Group B streptococci (GBS) express various surface antigens designated c, R, and X antigens. A new R-like surface protein from Streptococcus agalactiae strain Compton R has been identified by using a polyclonal antiserum raised against the R protein fraction of this strain to screen a lambda Zap library. DNA sequence analysis of positive clones allowed the prediction of the primary structure of a 105-kDa protein designated BPS protein (group B protective surface protein) that exhibited typical features of streptococcal surface proteins such as a signal sequence and a membrane anchor region but did not show significant similarity with other known sequences. Immunogold electron microscopy using a BPS-specific antiserum confirmed the surface location of BPS protein on S. agalactiae strain Compton R. Anti-BPS antibodies did not cross-react with R1 and R4 proteins expressed by two variant type III GBS strains but reacted with the parental streptococcal strain in Western blot and immunoprecipitation analyses. Separate R3 and BPS immunoprecipitation bands were observed when a cell extract of strain Compton R was tested with an antiserum against Compton R previously cross-absorbed to remove R4 antibodies. Immunization of mice with recombinant BPS protein by the subcutaneous route produced an efficient antigen-specific response, and immunized animals survived challenge with a lethal dose of a virulent strain. Therefore, BPS protein represents a new R-like protective antigen of GBS.

scholarly journals Sites and Determinants of Early Cleavages in the Proteolytic Processing Pathway of Reovirus Surface Protein σ3

2002 ◽  
Vol 76 (10) ◽  
pp. 5184-5197 ◽  
Author(s):  
Judit Jané-Valbuena ◽  
Laura A. Breun ◽  
Leslie A. Schiff ◽  
Max L. Nibert
Keyword(s):  
Structural Changes ◽  
Proper Time ◽  
Strain Differences ◽  
Surface Protein ◽  
Cellular Membrane ◽  
Proteolytic Processing ◽  
Target Cells ◽  
Inactive Form ◽  
Reovirus Type ◽  
Type 3

ABSTRACT Entry of mammalian reovirus virions into target cells requires proteolytic processing of surface protein σ3. In the virion, σ3 mostly covers the membrane-penetration protein μ1, appearing to keep it in an inactive form and to prevent it from interacting with the cellular membrane until the proper time in infection. The molecular mechanism by which σ3 maintains μ1 in this inactive state and the structural changes that accompany σ3 processing and μ1 activation, however, are not well understood. In this study we characterized the early steps in σ3 processing and determined their effects on μ1 function and particle infectivity. We identified two regions of high protease sensitivity, “hypersensitive” regions located at residues 208 to 214 and 238 to 244, within which all proteases tested selectively cleaved σ3 as an early step in processing. Further processing of σ3 was required for infection, consistent with the fact that the fragments resulting from these early cleavages remained bound to the particles. Reovirus type 1 Lang (T1L), type 3 Dearing (T3D), and T1L × T3D reassortant virions differed in the sites of early σ3 cleavage, with T1L σ3 being cleaved mainly at residues 238 to 244 and T3D σ3 being cleaved mainly at residues 208 to 214. These virions also differed in the rates at which the early cleavages occurred, with cleavage of T1L σ3 occurring faster than cleavage of T3D σ3. Analyses using chimeric and site-directed mutants of recombinant σ3 identified carboxy-proximal residues 344, 347, and 353 as the primary determinants of these strain differences. The spatial relationships between these more carboxy-proximal residues and the hypersensitive regions were discerned from the σ3 crystal structure. The results indicate that proteolytic processing of σ3 during reovirus disassembly is a multistep pathway with a number of molecular determinants.

scholarly journals Cloning, expression, purification, crystallization and preliminary X-ray diffraction analysis of glyceraldehyde-3-phosphate dehydrogenase fromStreptococcus agalactiaeNEM316

2014 ◽  
Vol 70 (7) ◽  
pp. 938-941 ◽  
Author(s):  
Revathi Nagarajan ◽  
Karthe Ponnuraj
Keyword(s):  
Signal Sequence ◽  
Structure Refinement ◽  
Group B Streptococcus ◽  
Surface Protein ◽  
Diffusion Method ◽  
Space Groups ◽  
Essential Enzyme ◽  
Bacteria And Fungi ◽  
Group B ◽  
Surface Adhesins

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is an essential enzyme involved in glycolysis. Despite lacking the secretory signal sequence, this cytosolic enzyme has been found localized at the surface of several bacteria and fungi. As a surface protein, GAPDH exhibits various adhesive functions, thereby facilitating colonization and invasion of host tissues.Streptococcus agalactiae, also known as group B streptococcus (GBS), binds onto the host using its surface adhesins and causes sepsis and pneumonia in neonates. GAPDH is one of the surface adhesins of GBS binding to human plasminogen and is a virulent factor associated with host colonization. Although the surface-associated GAPDH has been shown to bind to a variety of host extracellular matrix (ECM) molecules in various bacteria, the molecular mechanism underlying their interaction is not fully understood. To investigate this, structural studies on GAPDH ofS. agalactiaewere initiated. ThegapCgene ofS. agalactiaeNEM316 encoding GAPDH protein was cloned into pET-28a vector, overexpressed inEscherichia coliBL21(DE3) cells and purified to homogeneity. The purified protein was crystallized using the hanging-drop vapour-diffusion method. The GAPDH crystals obtained in two different crystallization conditions diffracted to 2.8 and 2.6 Å resolution, belonging to two different space groupsP21andP212121, respectively. The structure was solved by molecular replacement and structure refinement is now in progress.

scholarly journals Proteolytic processing of the L-type Ca2+ channel alpha11.2 subunit in neurons

F1000Research ◽  
2017 ◽  
Vol 6 ◽  
pp. 1166 ◽  
Author(s):  
Olivia R. Buonarati ◽  
Peter B. Henderson ◽  
Geoffrey G. Murphy ◽  
Mary C. Horne ◽  
Johannes W. Hell
Keyword(s):  
Gene Expression ◽  
Brain Tissue ◽  
Neuronal Excitability ◽  
Central Element ◽  
Proteolytic Processing ◽  
Full Length ◽  
Hek293 Cells ◽  
Specific Antibodies ◽  
C Terminus ◽  
Molecular Masses

Background: The L-type Ca2+ channel Cav1.2 is a prominent regulator of neuronal excitability, synaptic plasticity, and gene expression. The central element of Cav1.2 is the pore-forming α11.2 subunit. It exists in two major size forms, whose molecular masses have proven difficult to precisely determine. Recent work suggests that α11.2 is proteolytically cleaved between the second and third of its four pore-forming domains (Michailidis et al,. 2014). Methods: To better determine the apparent molecular masses (MR)of the α11.2 size forms, extensive systematic immunoblotting of brain tissue as well as full length and C-terminally truncated α11.2 expressed in HEK293 cells was conducted using six different region–specific antibodies against α11.2. Results: The full length form of α11.2 migrated, as expected, with an apparent MR of ~250 kDa. A shorter form of comparable prevalence with an apparent MR of ~210 kDa could only be detected in immunoblots probed with antibodies recognizing α11.2 at an epitope 400 or more residues upstream of the C-terminus. Conclusions: The main two size forms of α11.2 are the full length form and a shorter form, which lacks ~350 distal C-terminal residues. Midchannel cleavage as suggested by Michailidis et al. (2014) is at best minimal in brain tissue.

scholarly journals Cloning of fibA, Encoding an Immunogenic Subunit of the Fibril-Like Surface Structure ofPeptostreptococcus micros

1999 ◽  
Vol 181 (8) ◽  
pp. 2485-2491 ◽  
Author(s):  
B. H. A. Kremer ◽  
J. J. E. Bijlsma ◽  
J. G. Kusters ◽  
J. de Graaff ◽  
T. J. M. van Steenbergen
Keyword(s):  
Amino Acid ◽  
Surface Structure ◽  
Signal Sequence ◽  
Open Reading Frames ◽  
Periodontal Pathogen ◽  
Immunogold Electron Microscopy ◽  
Expression Library ◽  
Gram Positive ◽  
Secretion Signal ◽  
Specific Serum

ABSTRACT Although we are currently unaware of its biological function, the fibril-like surface structure is a prominent characteristic of the rough (Rg) genotype of the gram-positive periodontal pathogenPeptostreptococcus micros. The smooth (Sm) type of this species as well as the smooth variant of the Rg type (RgSm) lack these structures on their surface. A fibril-specific serum, as determined by immunogold electron microscopy, was obtained through adsorption of a rabbit anti-Rg type serum with excess bacteria of the RgSm type. This serum recognized a 42-kDa protein, which was subjected to N-terminal sequencing. Both clones of a λTriplEx expression library that were selected by immunoscreening with the fibril-specific serum contained an open reading frame, designatedfibA, encoding a 393-amino-acid protein (FibA). The 15-residue N-terminal amino acid sequence of the 42-kDa antigen was present at positions 39 to 53 in FibA; from this we conclude that the mature FibA protein contains 355 amino acids, resulting in a predicted molecular mass of 41,368 Da. The putative 38-residue signal sequence of FibA strongly resembles other gram-positive secretion signal sequences. The C termini of FibA and two open reading frames directly upstream and downstream of fibA exhibited significant sequence homology to the C termini of a group of secreted and surface-located proteins of other gram-positive cocci that are all presumably involved in anchoring of the protein to carbohydrate structures. We conclude that FibA is a secreted and surface-located protein and as such is part of the fibril-like structures.

scholarly journals The Road Less Traveled? Unconventional Protein Secretion at Parasite–Host Interfaces

2021 ◽  
Vol 9 ◽  
Author(s):  
Erina A. Balmer ◽  
Carmen Faso
Keyword(s):  
Protein Secretion ◽  
Cell Biology ◽  
Mammalian Cells ◽  
Cell Model ◽  
Signal Sequence ◽  
Model Organism ◽  
Secreted Proteins ◽  
Current Status ◽  
Secretory Proteins ◽  
Secretion Pathways

Protein secretion in eukaryotic cells is a well-studied process, which has been known for decades and is dealt with by any standard cell biology textbook. However, over the past 20 years, several studies led to the realization that protein secretion as a process might not be as uniform among different cargos as once thought. While in classic canonical secretion proteins carry a signal sequence, the secretory or surface proteome of several organisms demonstrated a lack of such signals in several secreted proteins. Other proteins were found to indeed carry a leader sequence, but simply circumvent the Golgi apparatus, which in canonical secretion is generally responsible for the modification and sorting of secretory proteins after their passage through the endoplasmic reticulum (ER). These alternative mechanisms of protein translocation to, or across, the plasma membrane were collectively termed “unconventional protein secretion” (UPS). To date, many research groups have studied UPS in their respective model organism of choice, with surprising reports on the proportion of unconventionally secreted proteins and their crucial roles for the cell and survival of the organism. Involved in processes such as immune responses and cell proliferation, and including far more different cargo proteins in different organisms than anyone had expected, unconventional secretion does not seem so unconventional after all. Alongside mammalian cells, much work on this topic has been done on protist parasites, including genera Leishmania, Trypanosoma, Plasmodium, Trichomonas, Giardia, and Entamoeba. Studies on protein secretion have mainly focused on parasite-derived virulence factors as a main source of pathogenicity for hosts. Given their need to secrete a variety of substrates, which may not be compatible with canonical secretion pathways, the study of mechanisms for alternative secretion pathways is particularly interesting in protist parasites. In this review, we provide an overview on the current status of knowledge on UPS in parasitic protists preceded by a brief overview of UPS in the mammalian cell model with a focus on IL-1β and FGF-2 as paradigmatic UPS substrates.

scholarly journals ASTN2 modulates synaptic strength by trafficking and degradation of surface proteins

2018 ◽  
Vol 115 (41) ◽  
pp. E9717-E9726 ◽  
Author(s):  
Hourinaz Behesti ◽  
Taylor R. Fore ◽  
Peter Wu ◽  
Zachi Horn ◽  
Mary Leppert ◽  
...  
Keyword(s):  
Surface Protein ◽  
Surface Expression ◽  
Autism Spectrum ◽  
Copy Number Variations ◽  
Surface Proteins ◽  
Synaptic Activity ◽  
Synaptic Proteins ◽  
Immunogold Electron Microscopy ◽  
Dynamic Regulation ◽  
Cerebellar Purkinje Cells

Surface protein dynamics dictate synaptic connectivity and function in neuronal circuits. ASTN2, a gene disrupted by copy number variations (CNVs) in neurodevelopmental disorders, including autism spectrum, was previously shown to regulate the surface expression of ASTN1 in glial-guided neuronal migration. Here, we demonstrate that ASTN2 binds to and regulates the surface expression of multiple synaptic proteins in postmigratory neurons by endocytosis, resulting in modulation of synaptic activity. In cerebellar Purkinje cells (PCs), by immunogold electron microscopy, ASTN2 localizes primarily to endocytic and autophagocytic vesicles in the cell soma and in subsets of dendritic spines. Overexpression of ASTN2 in PCs, but not of ASTN2 lacking the FNIII domain, recurrently disrupted by CNVs in patients, including in a family presented here, increases inhibitory and excitatory postsynaptic activity and reduces levels of ASTN2 binding partners. Our data suggest a fundamental role for ASTN2 in dynamic regulation of surface proteins by endocytic trafficking and protein degradation.

scholarly journals Expression and Processing of Proteins Encoded by the Saccharomyces Retrotransposon Ty5

2001 ◽  
Vol 75 (4) ◽  
pp. 1790-1797 ◽  
Author(s):  
Phillip A. Irwin ◽  
Daniel F. Voytas
Keyword(s):  
Reverse Transcriptase ◽  
Time Course ◽  
Immunoblot Analysis ◽  
Proteolytic Processing ◽  
Coding Region ◽  
Reading Frame ◽  
C Terminus ◽  
Virus Like Particle ◽  
Ionic Detergent ◽  
Time Course Experiment

ABSTRACT Retroelements (retrotransposons and retroviruses) have two genes in common: gag, which specifies structural proteins that form a virus or virus-like particle, andpol, which specifies catalytic proteins required for replication. For many retroelements, gag andpol are present on separate reading frames. Their expression is highly regulated, and the ratio of Gag to Pol is critical for retroelement replication. The Saccharomycesretrotransposon Ty5 contains a single open reading frame, and we characterized Gag and Pol expression by generating transpositionally active Ty5 elements with epitope tags at the N terminus or C terminus or within the integrase coding region. Immunoblot analysis identified two Gag species (Gag-p27 and Gag-p37), reverse transcriptase (Pol-p59), and integrase (Pol-p80), all of which are largely insoluble in the absence of urea or ionic detergent. These proteins result from proteolytic processing of a polyprotein, because elements with mutations in the presumed active site of Ty5 protease express a single tagged protein (Gag-Pol-p182). Protease mutants are also transpositionally inactive. In a time course experiment, we monitored protein expression, proteolytic processing, and transposition of a Ty5 element with identical epitope tags at its N and C termini. Both transposition and the abundance of Gag-p27 increased over time. In contrast, the levels of Gag-p37 and reverse transcriptase peaked after ∼14 h of induction and then gradually decreased. This may be due to differences in stability of Gag-p27 relative to Gag-p37 and reverse transcriptase. The ratio of Ty5 Gag to Pol averaged 5:1 throughout the time course experiment, suggesting that differential protein stability regulates the amounts of these proteins.

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