Structural basis for transthyretin amyloid formation in vitreous body of the eye

AbstractAmyloid transthyretin (ATTR) amyloidosis is characterized by the abnormal accumulation of ATTR fibrils in multiple organs. However, the structure of ATTR fibrils from the eye is poorly understood. Here, we used cryo-EM to structurally characterize vitreous body ATTR fibrils. These structures were distinct from previously characterized heart fibrils, even though both have the same mutation and type A pathology. Differences were observed at several structural levels: in both the number and arrangement of protofilaments, and the conformation of the protein fibril in each layer of protofilaments. Thus, our results show that ATTR protein structure and its assembly into protofilaments in the type A fibrils can vary between patients carrying the same mutation. By analyzing and matching the interfaces between the amino acids in the ATTR fibril with those in the natively folded TTR, we are able to propose a mechanism for the structural conversion of TTR into a fibrillar form.

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Amino acids lining the channel of the gamma-aminobutyric acid type A receptor identified by cysteine substitution.

Journal of Biological Chemistry ◽

10.1016/s0021-9258(20)80569-9 ◽

1993 ◽

Vol 268 (29) ◽

pp. 21505-21508

Author(s):

M Xu ◽

M.H. Akabas

Keyword(s):

Amino Acids ◽

Type A ◽

Aminobutyric Acid ◽

Gamma Aminobutyric Acid ◽

Cysteine Substitution ◽

Acid Type

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The Carboxy-Terminal Region ofFlavobacterium johnsoniaeSprB Facilitates Its Secretion by the Type IX Secretion System and Propulsion by the Gliding Motility Machinery

Journal of Bacteriology ◽

10.1128/jb.00218-19 ◽

2019 ◽

Vol 201 (19) ◽

Cited By ~ 5

Author(s):

Surashree S. Kulkarni ◽

Joseph J. Johnston ◽

Yongtao Zhu ◽

Zachary T. Hying ◽

Mark J. McBride

Keyword(s):

Amino Acids ◽

Amino Acid ◽

Cell Surface ◽

Type A ◽

Secretion System ◽

Gliding Motility ◽

Foreign Protein ◽

Type B ◽

Content Type ◽

Type Ix Secretion System

ABSTRACTFlavobacterium johnsoniaeSprB moves rapidly along the cell surface, resulting in gliding motility. SprB secretion requires the type IX secretion system (T9SS). Proteins secreted by the T9SS typically have conserved C-terminal domains (CTDs) belonging to the type A CTD or type B CTD family. Attachment of 70- to 100-amino-acid type A CTDs to a foreign protein allows its secretion. Type B CTDs are common but have received little attention. Secretion of the foreign protein superfolder green fluorescent protein (sfGFP) fused to regions spanning the SprB type B CTD (sfGFP-CTDSprB) was analyzed. CTDs of 218 amino acids or longer resulted in secretion of sfGFP, whereas a 149-amino-acid region did not. Some sfGFP was secreted in soluble form, whereas the rest was attached on the cell surface. Surface-attached sfGFP was rapidly propelled along the cell, suggesting productive interaction with the motility machinery. This did not result in rapid cell movement, which apparently requires additional regions of SprB. Secretion of sfGFP-CTDSprBrequired coexpression withsprF, which lies downstream ofsprB. SprF is similar in sequence toPorphyromonas gingivalisPorP. MostF. johnsoniaegenes encoding proteins with type B CTDs lie immediately upstream ofporP/sprF-like genes. sfGFP was fused to the type B CTD from one such protein (Fjoh_3952). This resulted in secretion of sfGFP only when it was coexpressed with its cognate PorP/SprF-like protein. These results highlight the need for extended regions of type B CTDs and for coexpression with the appropriate PorP/SprF-like protein for efficient secretion and cell surface localization of cargo proteins.IMPORTANCETheF. johnsoniaegliding motility adhesin SprB is delivered to the cell surface by the type IX secretion system (T9SS) and is rapidly propelled along the cell by the motility machinery. How this 6,497-amino-acid protein interacts with the secretion and motility machines is not known. Fusion of the C-terminal 218 amino acids of SprB to a foreign cargo protein resulted in its secretion, attachment to the cell surface, and rapid movement by the motility machinery. Efficient secretion of SprB required coexpression with the outer membrane protein SprF. Secreted proteins that have sequence similarity to SprB in their C-terminal regions are common in the phylumBacteroidetesand may have roles in adhesion, motility, and virulence.

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Gonococcal pili. Primary structure and receptor binding domain.

Journal of Experimental Medicine ◽

10.1084/jem.159.5.1351 ◽

1984 ◽

Vol 159 (5) ◽

pp. 1351-1370 ◽

Cited By ~ 79

Author(s):

G K Schoolnik ◽

R Fernandez ◽

J Y Tai ◽

J Rothbard ◽

E C Gotschlich

Keyword(s):

Amino Acids ◽

Receptor Binding ◽

Binding Domain ◽

Structural Basis ◽

Receptor Binding Domain ◽

Variable Regions ◽

Disulfide Linkage ◽

Polymeric Structure ◽

Antigenic Diversity ◽

Single Polypeptide Chain

The complete amino acid sequence of pilin from gonococcal strain MS11 and the sequence of constant and variable regions from strain R10 pilin have been determined in order to elucidate the structural basis for adherence function, antigenic diversity, and polymeric structure. The MS11 pilin sequence consists of 159 amino acids in a single polypeptide chain with two cysteines in disulfide linkage and serine-bonded phosphate residues. TC-2 (31-111), a soluble monomeric pilus peptide prepared by arginine-specific digestion, bound human endocervical, but not buccal or HeLa cells and therefore is postulated to encompass the receptor binding domain. Variable regions of CNBr-3 appear to confer antigenic diversity and comprise segments in which changes in the position of charged residues occur in hydrophilic, beta-turns. Residues 2-21 and 202-221 of gonococcal pilins and lower eucaryotic actins, respectively, exhibit 50% homology. When these residues are arranged at intervals of 100 degrees of arc on "helical wheels," the identical amino acids comprise a hydrophobic face on one side of the helix. This observation, the hydrophobic character of this region and the tendency for TC-1 (residues 1-30) to aggregate in water, suggest that this stretch interacts with other subunits to stabilize polymeric structure.

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Structural basis of adhesive binding by desmocollins and desmogleins

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1606272113 ◽

2016 ◽

Vol 113 (26) ◽

pp. 7160-7165 ◽

Cited By ~ 74

Author(s):

Oliver J. Harrison ◽

Julia Brasch ◽

Gorka Lasso ◽

Phinikoula S. Katsamba ◽

Goran Ahlsen ◽

...

Keyword(s):

Amino Acids ◽

Crystal Structures ◽

Structural Basis ◽

Cellular Interactions ◽

Opposite Charge ◽

Charged Amino Acids ◽

Structural Framework ◽

Classical Cadherins ◽

Coated Bead

Desmosomes are intercellular adhesive junctions that impart strength to vertebrate tissues. Their dense, ordered intercellular attachments are formed by desmogleins (Dsgs) and desmocollins (Dscs), but the nature of trans-cellular interactions between these specialized cadherins is unclear. Here, using solution biophysics and coated-bead aggregation experiments, we demonstrate family-wise heterophilic specificity: All Dsgs form adhesive dimers with all Dscs, with affinities characteristic of each Dsg:Dsc pair. Crystal structures of ectodomains from Dsg2 and Dsg3 and from Dsc1 and Dsc2 show binding through a strand-swap mechanism similar to that of homophilic classical cadherins. However, conserved charged amino acids inhibit Dsg:Dsg and Dsc:Dsc interactions by same-charge repulsion and promote heterophilic Dsg:Dsc interactions through opposite-charge attraction. These findings show that Dsg:Dsc heterodimers represent the fundamental adhesive unit of desmosomes and provide a structural framework for understanding desmosome assembly.

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Structural basis for the protective role of sulfite against transthyretin amyloid formation

Biochimica et Biophysica Acta (BBA) - Proteins and Proteomics ◽

10.1016/j.bbapap.2006.10.015 ◽

2007 ◽

Vol 1774 (1) ◽

pp. 59-64 ◽

Cited By ~ 15

Author(s):

Luís Gales ◽

Maria J. Saraiva ◽

Ana M. Damas

Keyword(s):

Protective Role ◽

Structural Basis ◽

Amyloid Formation

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Human Group C Rotavirus VP8*s Recognize Type A Histo-Blood Group Antigens as Ligands

Journal of Virology ◽

10.1128/jvi.00442-18 ◽

2018 ◽

Vol 92 (11) ◽

Cited By ~ 7

Author(s):

Xiaoman Sun ◽

Lihong Wang ◽

Jianxun Qi ◽

Dandi Li ◽

Mengxuan Wang ◽

...

Keyword(s):

Ligand Binding ◽

Binding Site ◽

Blood Group ◽

Specific Interaction ◽

Type A ◽

Host Susceptibility ◽

Structural Basis ◽

Receptor Interaction ◽

Blood Group Antigens ◽

Group Species

ABSTRACTGroup/species C rotaviruses (RVCs) have been identified as important pathogens of acute gastroenteritis (AGE) in children, family-based outbreaks, as well as animal infections. However, little is known regarding their host-specific interaction, infection, and pathogenesis. In this study, we performed serial studies to characterize the function and structural features of a human G4P[2] RVC VP8* that is responsible for the host receptor interaction. Glycan microarrays demonstrated that the human RVC VP8* recognizes type A histo-blood group antigens (HBGAs), which was confirmed by synthetic glycan-/saliva-based binding assays and hemagglutination of red blood cells, establishing a paradigm of RVC VP8*-glycan interactions. Furthermore, the high-resolution crystal structure of the human RVC VP8* was solved, showing a typical galectin-like structure consisting of two β-sheets but with significant differences from cogent proteins of group A rotaviruses (RVAs). The VP8* in complex with a type A trisaccharide displays a novel ligand binding site that consists of a particular set of amino acid residues of the C-D, G-H, and K-L loops. RVC VP8* interacts with type A HBGAs through a unique mechanism compared with that used by RVAs. Our findings shed light on the host-virus interaction and the coevolution of RVCs and will facilitate the development of specific antivirals and vaccines.IMPORTANCEGroup/species C rotaviruses (RVCs), members ofReoviridaefamily, infect both humans and animals, but our knowledge about the host factors that control host susceptibility and specificity is rudimentary. In this work, we characterized the glycan binding specificity and structural basis of a human RVC that recognizes type A HBGAs. We found that human RVC VP8*, the rotavirus host ligand binding domain that shares only ∼15% homology with the VP8* domains of RVAs, recognizes type A HBGA at an as-yet-unknown glycan binding site through a mechanism distinct from that used by RVAs. Our new advancements provide insights into RVC-cell attachment, the critical step of virus infection, which will in turn help the development of control and prevention strategies against RVs.

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Structural basis for divergent and convergent evolution of catalytic machineries in plant aromatic amino acid decarboxylase proteins

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1920097117 ◽

2020 ◽

Vol 117 (20) ◽

pp. 10806-10817 ◽

Cited By ~ 6

Author(s):

Michael P. Torrens-Spence ◽

Ying-Chih Chiang ◽

Tyler Smith ◽

Maria A. Vicent ◽

Yi Wang ◽

...

Keyword(s):

Amino Acids ◽

Amino Acid ◽

Convergent Evolution ◽

Structural Features ◽

Divergent Evolution ◽

Structural Basis ◽

Acid Decarboxylase ◽

Substrate Selectivity ◽

Amino Acid Decarboxylase ◽

Catalytic Mechanisms

Radiation of the plant pyridoxal 5′-phosphate (PLP)-dependent aromatic l-amino acid decarboxylase (AAAD) family has yielded an array of paralogous enzymes exhibiting divergent substrate preferences and catalytic mechanisms. Plant AAADs catalyze either the decarboxylation or decarboxylation-dependent oxidative deamination of aromatic l-amino acids to produce aromatic monoamines or aromatic acetaldehydes, respectively. These compounds serve as key precursors for the biosynthesis of several important classes of plant natural products, including indole alkaloids, benzylisoquinoline alkaloids, hydroxycinnamic acid amides, phenylacetaldehyde-derived floral volatiles, and tyrosol derivatives. Here, we present the crystal structures of four functionally distinct plant AAAD paralogs. Through structural and functional analyses, we identify variable structural features of the substrate-binding pocket that underlie the divergent evolution of substrate selectivity toward indole, phenyl, or hydroxyphenyl amino acids in plant AAADs. Moreover, we describe two mechanistic classes of independently arising mutations in AAAD paralogs leading to the convergent evolution of the derived aldehyde synthase activity. Applying knowledge learned from this study, we successfully engineered a shortened benzylisoquinoline alkaloid pathway to produce (S)-norcoclaurine in yeast. This work highlights the pliability of the AAAD fold that allows change of substrate selectivity and access to alternative catalytic mechanisms with only a few mutations.

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