scholarly journals An M protein coiled coil unfurls and exposes its hydrophobic core to capture LL-37

2022 ◽  
Author(s):  
Piotr Kolesinski ◽  
Kuei-Chen Wang ◽  
Yujiro Hirose ◽  
Victor Nizet ◽  
Partho Ghosh
Keyword(s):  
Specific Binding ◽  
Coiled Coil ◽  
M Protein ◽  
Human Populations ◽  
Hydrophobic Core ◽  
Antigenic Variant ◽  
Specific Detail ◽  
Interaction Sites ◽  
Interaction Mode ◽  
M Proteins

Surface-associated, coiled-coil M proteins of Streptococcus pyogenes (Strep A) disable human immunity through interaction with select proteins. However, coiled coils lack features typical of protein-protein interaction sites, and it is therefore challenging to understand how M proteins achieve specific binding, for example, with the human antimicrobial peptide LL-37, which results in its neutralization. The crystal structure of a complex of LL-37 with M87 protein, an antigenic variant from a strain that is an emerging threat, revealed a novel interaction mode. The M87 coiled coil unfurled and asymmetrically exposed its hydrophobic core to capture LL-37. A single LL-37 molecule bound M87 in the crystal, but in solution recruited additional LL-37 molecules, consistent with a protein trap neutralization mechanism. The interaction mode visualized crystallographically was verified to contribute significantly to LL-37 resistance in an M87 Strep A strain, and was identified to be conserved in a number of other M protein types that are prevalent in human populations. Our results provide specific detail for therapeutic inhibition of LL-37 neutralization by M proteins.

scholarly journals Antigenic domains of the streptococcal Pep M5 protein. Localization of epitopes crossreactive with type 6 M protein and identification of a hypervariable region of the M molecule.

1986 ◽  
Vol 163 (1) ◽  
pp. 129-138 ◽  
Author(s):  
B N Manjula ◽  
A S Acharya ◽  
T Fairwell ◽  
V A Fischetti
Keyword(s):  
Protein Localization ◽  
Hypervariable Region ◽  
Coiled Coil ◽  
M Protein ◽  
Terminal Domain ◽  
Coil Structure ◽  
M Proteins ◽  
Group A ◽  
Antigenic Domains ◽  
Antigenic Epitopes

Pep M5, the pepsin-derived N-terminal half of the group A streptococcal type 5 M protein exhibits immunologic crossreaction with type 6 M protein, localizing some of the M6-crossreactive epitope(s) within this segment of the M5 protein. Based on the amino acid sequence of the Pep M5 protein, two structurally distinct domains have been recognized within its coiled-coil structure. We have now found that peptides derived from both the structurally distinct domains of the Pep M5 protein contain antigenic epitopes. Furthermore, only the peptides from the C-terminal domain of the Pep M5 protein crossreacted with rabbit anti-M6 sera, whereas those from the N-terminal domain did not. Consistent with this, sequence analyses of the arginyl peptides of the Pep M6 protein, the pepsin-derived N-terminal half of the M6 protein, revealed extensive homology of some of these peptides with regions within the C-terminal domain of the Pep M5 molecule. While an arginyl peptide of the Pep M6 protein exhibits 84% homology with region 150-186 of the Pep M5 protein, the C-terminal hexadecapeptide of the Pep M6 protein is virtually identical with the corresponding region of the Pep M5 protein. These results are suggestive of conformational similarities in the region around the pepsin-susceptible site within the M5 and M6 proteins. In addition, one or more epitopes of the M5 protein that are crossreactive with the M6 protein may be placed close to the pepsin-susceptible site of the M5 protein. Previous studies have suggested the N-terminal half of the M proteins to be the variable part of the molecule among the different M protein serotypes. The present results suggest that the N-terminal quarter of the M protein may represent the hypervariable domain of the M molecule.

scholarly journals Role of Small Envelope Protein in Sustaining the Intracellular and Extracellular Levels of Hepatitis B Virus Large and Middle Envelope Proteins

Viruses ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 613
Author(s):  
Jing Zhang ◽  
Yongxiang Wang ◽  
Shuwen Fu ◽  
Quan Yuan ◽  
Qianru Wang ◽  
...  
Keyword(s):  
Envelope Proteins ◽  
Full Length ◽  
M Protein ◽  
Intracellular Level ◽  
S Protein ◽  
L Protein ◽  
M Proteins ◽  
B Virus ◽  
Subviral Particle ◽  
Genotype A

Hepatitis B virus (HBV) expresses co-terminal large (L), middle (M), and small (S) envelope proteins. S protein drives virion and subviral particle secretion, whereas L protein inhibits subviral particle secretion but coordinates virion morphogenesis. We previously found that preventing S protein expression from a subgenomic construct eliminated M protein. The present study further examined impact of S protein on L and M proteins. Mutations were introduced to subgenomic construct of genotype A or 1.1mer replication construct of genotype A or D, and viral proteins were analyzed from transfected Huh7 cells. Mutating S gene ATG to prevent expression of full-length S protein eliminated M protein, reduced intracellular level of L protein despite its blocked secretion, and generated a truncated S protein through translation initiation from a downstream ATG. Truncated S protein was secretion deficient and could inhibit secretion of L, M, S proteins from wild-type constructs. Providing full-length S protein in trans rescued L protein secretion and increased its intracellular level from mutants of lost S gene ATG. Lost core protein expression reduced all the three envelope proteins. In conclusion, full-length S protein could sustain intracellular and extracellular L and M proteins, while truncated S protein could block subviral particle secretion.

scholarly journals The Hydrophobic Core of Twin-Arginine Signal Sequences Orchestrates Specific Binding to Tat-Pathway Related Chaperones

PLoS ONE ◽  
2012 ◽  
Vol 7 (3) ◽  
pp. e34159 ◽  
Author(s):  
Anitha Shanmugham ◽  
Adil Bakayan ◽  
Petra Völler ◽  
Joost Grosveld ◽  
Holger Lill ◽  
...  
Keyword(s):  
Specific Binding ◽  
Hydrophobic Core ◽  
Signal Sequences ◽  
Tat Pathway

scholarly journals Two Overlapping Domains of a Lyssavirus Matrix Protein That Acts on Different Cell Death Pathways

2010 ◽  
Vol 84 (19) ◽  
pp. 9897-9906 ◽  
Author(s):  
Florence Larrous ◽  
Alireza Gholami ◽  
Shahul Mouhamad ◽  
Jérôme Estaquier ◽  
Hervé Bourhy
Keyword(s):  
Cell Death ◽  
Amino Acid ◽  
Matrix Protein ◽  
Full Length ◽  
M Protein ◽  
Genotype 3 ◽  
Cell Death Pathways ◽  
Acid Fragment ◽  
M Proteins ◽  
Cellular Apoptosis

ABSTRACT The lyssavirus matrix (M) protein induces apoptosis. The regions of the M protein that are essential for triggering cell death pathways are not yet clearly defined. We therefore compared the M proteins from two viruses that have contrasting characteristics in terms of cellular apoptosis: a genotype 3 lyssavirus, Mokola virus (MOK), and a genotype 1 rabies virus isolated from a dog from Thailand (THA). We identified a 20-amino-acid fragment (corresponding to positions 67 to 86) that retained the cell death activities of the full-length M protein from MOK via both the tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and inhibition of cytochrome c oxidase (CcO) activity. We found that the amino acids at positions 77 and 81 have an essential role in triggering these two cell death pathways. Directed mutagenesis demonstrated that the amino acid at position 77 affects CcO activity, whereas the amino acid at position 81 affects TRAIL-dependent apoptosis. Mutations in the full-length M protein that compromised induction of either of these two pathways resulted in delayed apoptosis compared with the time to apoptosis for the nonmutated control.

scholarly journals Immunodominant and neutralizing linear B cell epitopes spanning the spike and membrane proteins of Porcine Epidemic Diarrhea Virus

2021 ◽  
Author(s):  
Kanokporn Polyiam ◽  
Marasri Ruengjitchatchawalya ◽  
Phenjun Mekvichitsaeng ◽  
Kampon Kaeoket ◽  
Tawatchai Hoonsuwan ◽  
...  
Keyword(s):  
B Cell ◽  
Porcine Epidemic Diarrhea Virus ◽  
M Protein ◽  
B Cell Epitopes ◽  
Diarrhea Virus ◽  
M Proteins ◽  
Porcine Epidemic Diarrhea ◽  
Neutralizing Epitopes ◽  
Immunodominant Epitopes ◽  
Linear B

AbstractPorcine Epidemic Diarrhea Virus (PEDV) is the causative agent of PED, an enteric disease that causes high mortality rates in piglets. PEDV is an alphacoronavirus that has high genetic diversity. Insights into neutralizing B cell epitopes of all genetically diverse PEDV strains are of importance, particularly for designing a vaccine that can provide broad protection against PEDV. In this work, we aimed to explore the landscape of linear B cell epitopes on the spike (S) and membrane (M) proteins of global PEDV strains. All amino acid sequences of the PEDV S and M proteins were retrieved from the NCBI database and grouped. Immunoinformatics-based methods were next developed and used to identify putative linear B cell epitopes from 14 and 5 consensus sequences generated from distinct groups of the S and M proteins, respectively. ELISA testing predicted peptides with PEDV-positive sera revealed 9 novel immunodominant epitopes on the S protein. Importantly, 7 of these novel immunodominant epitopes and other subdominant epitopes were demonstrated to be neutralizing epitopes by neutralization-inhibition assay. Additionally, our study shows the first time that M protein is also the target of neutralizing antibodies as 7 neutralizing epitopes in the M protein were identified. Conservancy analysis revealed that epitopes in the S1 subunit are more variable than those in the S2 subunit and M protein. In this study, we offer the immunoinformatics approach for linear B cell epitope identification and a more complete profile of linear B cell epitopes across the PEDV S and M proteins, which may contribute to the development of a greater PEDV vaccine as well as peptide-based immunoassays.

scholarly journals Regulatory coiled-coil domains promote head-to-head assemblies of AAA+ chaperones essential for tunable activity control

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Marta Carroni ◽  
Kamila B Franke ◽  
Michael Maurer ◽  
Jasmin Jäger ◽  
Ingo Hantke ◽  
...  
Keyword(s):  
Atpase Activity ◽  
Stress Resistance ◽  
Ground State ◽  
Resting State ◽  
Coiled Coil ◽  
Ring Structure ◽  
Cellular Toxicity ◽  
Constitutive Activation ◽  
Interaction Sites ◽  
Bacterial Protease

Ring-forming AAA+ chaperones exert ATP-fueled substrate unfolding by threading through a central pore. This activity is potentially harmful requiring mechanisms for tight repression and substrate-specific activation. The AAA+ chaperone ClpC with the peptidase ClpP forms a bacterial protease essential to virulence and stress resistance. The adaptor MecA activates ClpC by targeting substrates and stimulating ClpC ATPase activity. We show how ClpC is repressed in its ground state by determining ClpC cryo-EM structures with and without MecA. ClpC forms large two-helical assemblies that associate via head-to-head contacts between coiled-coil middle domains (MDs). MecA converts this resting state to an active planar ring structure by binding to MD interaction sites. Loss of ClpC repression in MD mutants causes constitutive activation and severe cellular toxicity. These findings unravel an unexpected regulatory concept executed by coiled-coil MDs to tightly control AAA+ chaperone activity.

scholarly journals How does temperature affect the dynamics of SARS-CoV-2 M proteins? Insights from Molecular Dynamics Simulations

2021 ◽  
Author(s):  
Soumya Lipsa Rath ◽  
Madhusmita Tripathy ◽  
Nabanita Mandal
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Membrane Lipids ◽  
Membrane System ◽  
Host Cells ◽  
Coarse Grained ◽  
M Protein ◽  
Effect Of Temperature ◽  
M Proteins ◽  
Dynamics Simulations

Enveloped viruses, in general, have several transmembrane proteins and glycoproteins, which assist the virus in entry and attachment onto the host cells. These proteins also play a significant role in determining the shape and size of the newly formed virus particles. The lipid membrane and the embedded proteins affect each other in non-trivial ways during the course of the viral life cycle. Unravelling the nature of the protein-protein and protein-lipid interactions, under various environmental and physiological conditions, could therefore prove to be crucial in development of therapeutics. Here, we study the M protein of SARS-CoV-2 to understand the effect of temperature on the properties of the protein-membrane system. The membrane embedded dimeric M proteins were studied using atomistic and coarse-grained molecular dynamics simulations at temperatures ranging between 10 and 50 ˚C. While temperature induced fluctuations should be monotonic, we observe a steady rise in the protein dynamics up to 40 ˚C, beyond which it surprisingly reverts back to the low temperature behaviour. Detailed investigation reveals disordering of the membrane lipids in the presence of the protein, which induces additional curvature around the transmembrane region. Coarse-grained simulations indicate temperature dependent aggregation of M protein dimers. Our study clearly indicates that the dynamics of membrane lipids and integral M protein of SARS-CoV-2 enables it to better associate and aggregate only at a certain temperature range (i.e., ~30 to 40 ˚C). This can have important implications in the protein aggregation and subsequent viral budding/fission processes.   

Distinct serotypes of streptococcal M proteins mediate fibrinogen-dependent platelet activation and pro-inflammatory effects

2021 ◽  
Author(s):  
Frida Palm ◽  
Sounak Chowdhury ◽  
Sara Wettemark ◽  
Johan Malmström ◽  
Lotta Happonen ◽  
...  
Keyword(s):  
Platelet Activation ◽  
M Protein ◽  
Multiparameter Flow Cytometry ◽  
Invasive Infection ◽  
Monocyte Activation ◽  
Platelet Surface ◽  
Sequence Variations ◽  
M Proteins ◽  
Inflammatory State ◽  
Life Threatening

Sepsis is a life-threatening complication of infection that is characterised by a dysregulated inflammatory state and disturbed hemostasis. Platelets are the main regulators of hemostasis, and they also respond to inflammation. The human pathogen Streptococcus pyogenes can cause local infection that may progress to sepsis. There are more than 200 different serotypes of S. pyogenes defined according to sequence variations in the M protein. The M1 serotype is among ten serotypes that are predominant in invasive infection. M1 protein can be released from the surface and has previously been shown to generate platelet, neutrophil and monocyte activation. The platelet dependent pro-inflammatory effects of other serotypes of M protein associated with invasive infection (M3, M5, M28, M49 and M89) is now investigated using a combination of multiparameter flow cytometry, ELISA, aggregometry and quantitative mass spectrometry. We demonstrate that only M1-, M3- and M5 protein serotypes can bind fibrinogen in plasma and mediate fibrinogen and IgG dependent platelet activation and aggregation, release of granule proteins, upregulation of CD62P to the platelet surface, and complex formation with neutrophils and monocytes. Neutrophil and monocyte activation, determined as upregulation of surface CD11b, is also mediated by M1-, M3- and M5 protein serotypes, while M28-, M49- or M89 proteins failed to mediate activation of platelets or leukocytes. Collectively, our findings reveal novel aspects of the immunomodulatory role of fibrinogen acquisition and platelet activation during streptococcal infections.

scholarly journals Evidence for two distinct classes of streptococcal M protein and their relationship to rheumatic fever.

1989 ◽  
Vol 169 (1) ◽  
pp. 269-283 ◽  
Author(s):  
D Bessen ◽  
K F Jones ◽  
V A Fischetti
Keyword(s):  
Rheumatic Fever ◽  
Class Ii ◽  
Class I ◽  
M Protein ◽  
Repeat Region ◽  
Streptococcal M Protein ◽  
Antigenic Relatedness ◽  
M Proteins ◽  
Protein Molecules ◽  
Definition Of

The antigenic relatedness of surface-exposed portions of M protein molecules derived from group A streptococcal isolates representing more than 50 distinct serotypes was examined. The data indicate that the majority of serotypes fall into two major classes. Class I M protein molecules share a surface-exposed, antigenic domain comprising the C repeat region defined for M6 protein. The C repeat region of M6 protein is located adjacent to the COOH-terminal side of the pepsin-susceptible site. In contrast, Class I M proteins display considerably less antigenic relatedness to the B repeat region of M6 protein, which lies immediately NH2-terminal to the pepsin site. Surface-exposed portions of Class II M proteins lack antigenic epitopes that define the Class I molecules. Studies in the 1970s demonstrated that M protein serotypes can be divided into two groups based on both immunoreactivity directed to an unknown surface antigen (termed M-associated protein) and production of serum opacity factor. These two groups closely parallel our current definition of Class I and Class II serotypes. Both classes retain the antiphagocytic property characteristic of M protein, and Class II M proteins share some immunodeterminants with Class I M proteins, although the shared determinants do not appear to be exposed on the streptococcal surface. Nearly all streptococcal serotypes associated with outbreaks of acute rheumatic fever express M protein of a Class I serotype. Thus, the surface-exposed, conserved C repeat domain of Class I serotypes may be a virulence determinant for rheumatic fever.

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