136 research outputs found
Targets and cross-reactivity of human T cell recognition of common cold coronaviruses
No full textThe coronavirus (CoV) family includes several viruses infecting humans, highlighting the importance of exploring pan-CoV vaccine strategies to provide broad adaptive immune protection. We analyze T cell reac-tivity against representative Alpha (NL63) and Beta (OC43) common cold CoVs (CCCs) in pre-pandemic sam-ples. S, N, M, and nsp3 antigens are immunodominant, as shown for severe acute respiratory syndrome 2 (SARS2), while nsp2 and nsp12 are Alpha or Beta specific. We further identify 78 OC43-and 87 NL63-specific epitopes, and, for a subset of those, we assess the T cell capability to cross-recognize sequences from repre-sentative viruses belonging to AlphaCoV, sarbecoCoV, and Beta-non-sarbecoCoV groups. We find T cell cross-reactivity within the Alpha and Beta groups, in 89% of the instances associated with sequence conser-vation >67%. However, despite conservation, limited cross-reactivity is observed for sarbecoCoV, indicating that previous CoV exposure is a contributing factor in determining cross-reactivity. Overall, these results pro-vide critical insights in developing future pan-CoV vaccines
QUALITIES OF THE PROTECTIVE ANTIBODY RESPONSE AGAINST DENGUE VIRUS INFECTION
No full textDengue viruses (DENV1-4) cause 390 million annual infections across the globe. Primary DENV infection elicits an antibody response that is thought to provide lifelong protection against re-infection with the same serotype. A protective antibody response provided by vaccination would be the best tool available to prevent DENV related disease but the currently licensed DENV vaccine had variable efficacy. We still have large knowledge gaps that need to be addressed surrounding qualities of protective antibodies. My thesis defines three properties of the protective antibody response to DENV infection and vaccination. Isolation and characterization of potently neutralizing monoclonal antibodies identified the majority of these antibodies bind across multiple DENV E-proteins (quaternary epitopes) on the virion surface. For my thesis, I defined the epitope of a potently neutralizing antibody to the closely related Zika virus (ZIKV) and used its structure to guide questions about the mechanism of potent neutralization. I identify that targeting a quaternary epitope is essential for potent neutralization. Recently, a DENV vaccine that induced neutralizing antibodies did not demonstrate protection in DENV naïve individuals. To understand qualities of a protective neutralizing antibody response, I compared the antibody response elicited by WT DENV infection to the antibody response elicited in DENV vaccinated individuals who subsequently experience infection. I observed a specific fraction of the neutralizing antibody response correlated with protection. While antibody response to primary infection protects against clinically significant disease, it is unclear if the antibody response provides sterilizing immunity as rare, homotypic reinfections are reported. To understand if antibody response to primary infection provides sterilizing immunity, I used a unbalanced DENV vaccine as a human challenge model. The majority of individuals respond to the vaccine, regardless of DENV serostatus. My results help guide future development of DENV vaccines to achieve a protective, balanced vaccine.Doctor of Philosoph
Identification of an artificial peptide motif that binds and stabilizes reduced human DJ-1
No full textThe X-ray structure of human acid-beta-glucosidase : Implications for second-generation enzyme replacement therapy
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Author Correction: A shape-shifting redox foldase contributes to Proteus mirabilis copper resistance
No full textCorrection to: Nature Communications; https://doi.org/10.1038/ncomms16065; published online 19 July 2017.
This Article contains errors in Fig. 1, Table 1 and the Methods section. In panel c, the labels for PmScsC and EcDsbC in the upper two curves are interchanged. In Table 1 and the Methods section entitled ‘Extended structure’, the space group of the extended PmScsC structure is incorrectly referred to as H32 and should read H32. Correct versions of Fig. 1 and Table 1 are presented below; the errors have not been corrected in the Article.Full Tex
Four structural subclasses of the antivirulence drug target disulfide oxidoreductase DsbA provide a platform for design of subclass-specific inhibitors
No full textBy catalyzing oxidative protein folding, the bacterial disulfide bond protein A (DsbA) plays an essential role in the assembly of many virulence factors. Predictably, DsbA disruption affects multiple downstream effector molecules, resulting in pleiotropic effects on the virulence of important human pathogens. These findings mark DsbA as a master regulator of virulence, and identify the enzyme as a target for a new class of antivirulence agents that disarm pathogenic bacteria rather than killing them. The purpose of this article is to discuss and expand upon recent findings on DsbA and to provide additional novel insights into the druggability of this important disulfide oxidoreductase by comparing the structures and properties of 13 well-characterized DsbA enzymes. Our structural analysis involved comparison of the overall fold, the surface properties, the conformations of three loops contributing to the binding surface and the sequence identity of residues contributing to these loops. Two distinct structural classes were identified, classes I and II, which are differentiated by their central β-sheet arrangements and which roughly separate the DsbAs produced by Gram-negative from Gram-positive organisms. The classes can be further subdivided into a total of four subclasses on the basis of surface features. Class Ia is equivalent to the Enterobacteriaceae class that has been defined previously. Bioinformatic analyses support the classification of DsbAs into 3 of the 4 subclasses, but did not pick up the 4th subclass which is only apparent from analysis of DsbA electrostatic surface properties. In the context of inhibitor development, the discrete structural subclasses provide a platform for developing DsbA inhibitory scaffolds with a subclass-wide spectrum of activity. We expect that more DsbA classes are likely to be identified, as enzymes from other pathogens are explored, and we highlight the issues associated with structure-based inhibitor development targeting this pivotal mediator of bacterial virulence. This article is part of a Special Issue entitled: Thiol-Based Redox Processes
Engineered variants provide new insight into the structural properties important for activity of the highly dynamic, trimeric protein disulfide isomerase ScsC from Proteus mirabilis
No full textSuppressor of copper sensitivity protein C from Proteus mirabilis (PmScsC) is a homotrimeric disulfide isomerase that plays a role in copper tolerance, which is a key virulence trait of this uropathogen. Each protomer of the enzyme has an N-terminal trimerization stem (59 residues) containing a flexible linker (11 residues) connected to a thioredoxin-fold-containing catalytic domain (163 residues). Here, two PmScsC variants, PmScsC Delta N and PmScsC Delta Linker, are characterized. PmScsC Delta N is an N-terminally truncated form of the protomer with two helices of the trimerization stem removed, generating a protein with dithiol oxidase rather than disulfide isomerase activity. The crystal structure of PmScsC Delta N reported here reveals, as expected, a monomer that is structurally similar to the catalytic domain of native PmScsC. The second variant, PmScsC Delta Linker, was designed to remove the 11-amino-acid linker, and it is shown that it generates a protein that has neither disulfide isomerase nor dithiol oxidase activity. The crystal structure of PmScsC Delta Linker reveals a trimeric arrangement, with the catalytic domains packed together very closely. Small-angle X-ray scattering analysis found that native PmScsC is predominantly trimeric in solution even at low concentrations, whereas PmScsC Delta Linker exists as an equilibrium between monomeric, dimeric and trimeric states, with the monomeric form dominating at low concentrations. These findings increase the understanding of disulfide isomerase activity, showing how (i) oligomerization, (ii) the spacing between and (iii) the dynamic motion of catalytic domains in PmScsC all contribute to its native function
The multidrug resistance IncA/C transferable plasmid encodes a novel domain swapped dimeric protein disulfide isomerase
No full textBackground: Bacterial IncA/C plasmids distribute antibiotic resistance genes and encode a conserved thioredoxin-fold protein (DsbP). Results: DsbP shuffles incorrect disulfide bonds in misfolded proteins, and its structure diverges from previously characterized disulfide isomerases. Conclusion: Plasmid-encoded DsbP is a novel domain-swapped protein-disulfide isomerase. Significance: IncA/C plasmids may encode this protein proofreading machinery to ensure horizontal gene transfer of antibiotic resistance genes
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