Complete nucleotide sequence of the neuraminidase gene of influenza B virus.

Shaw, Michael; Lamb, Robert A.; Erickson, Bruce W.; Briedis, Dalius J.; Choppin, Purnell W.

doi:10.1073/pnas.79.22.6817

Cited by 72 publications

(21 citation statements)

References 27 publications

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“…The predicted amino acid sequences were compared with a published sequence in the Protein Identification Resource data base (version 26). Interestingly, all three genes share a region of significant homology with bacterial and viral sialidases (22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36). This region of the deduced T. cruzi proteins is compared to the homologous region-of the Clostridium perfringens sialidase in Fig.…”

Section: Resultsmentioning

confidence: 99%

The major 85-kDa surface antigen of the mammalian-stage forms of Trypanosoma cruzi is a family of sialidases.

Kahn

Colbert

Wallace

et al. 1991

Proc. Natl. Acad. Sci. U.S.A.

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Trypanosoma cruzi, an intracellular protozoan parasite infecting a wide variety of vertebrates, is the agent responsible for Chagas disease in humans. An estimated 15-20 million people in South and Central America are infected with the parasite. Chagas disease often results in severe autoimmune and inflammatory pathology and is the major cause of heart failure in endemic areas. Nevertheless, little is known about the host-parasite interactions that lead to this pathology. We have previously cloned several members of a large gene family (SA85-1) and shown that these genes encode 85-kDa T. cruzi, mammalian-stage-specific, surface antigens. Here we report that members of the SA85-1 family possess sialidase activity and are shed by the parasite. We suggest that the sialidases may contribute to the pathology during T. cruzi infection by cleaving sialic acid from cells of the immune system.Trypanosoma cruzi is the causative agent of Chagas disease, affecting 15-20 million people. Approximately 10% of cases are fatal, generally as a result of heart failure, megacolon, or megaesophagus. The parasites grow as epimastigotes in reduviid bugs and are transmitted to vertebrates in the feces of the insects. In the vertebrate, the parasites replicate intracellularly as amastigotes and circulate as trypomastigotes (1). T. cruzi can infect a wide range of mammalian species and proliferates in the cytoplasm of many different cell types (2). Acute infection with T. cruzi results in severe immunodepression (3). The lifelong chronic phase that follows is characterized by autoimmune pathology (3). It is not known how the parasites gain entry into their various host cells. Nor is it known how they evade the host immune system during the chronic infection. Finally, the mechanisms involved in immunodepression and autoimmunity have not been determined.Several proteins have been characterized on the surface of T. cruzi mammalian-stage forms (4-12). Among these surface antigens, a large family of closely related 85-kDa proteins appear to be the predominant species (13-16). We have examined 10 members of the SA85-1 (surface antigen, 85 kDa) gene family from the CL strain and shown that at least three of these antigens are simultaneously expressed on the surface of each trypomastigote and amastigote in the population (13). The SA85-1 surface antigens, which are only present on parasites during the mammalian stages of their life cycle, are encoded by >100 genes with '80% homology to one another (13). We have characterized subsets of the SA85-1 family with specific oligonucleotide probes and antibodies (13). The SA85-1.1 gene is present in two telomerelinked copies and the SA85-1.2 gene exists as a single non-telomere-linked copy (13). We report here that the SA85-1 genes contain significant sequence homology to bacterial and viral sialidases and that antibodies purified on recombinant SA85-1 affinity columns precipitate the majority of cell-bound and shed sialidase activity from T. cruzi. § MATERIALS AND METHODS T. cruzi. T. cruzi CL ...

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Section: Resultsmentioning

confidence: 99%

The major 85-kDa surface antigen of the mammalian-stage forms of Trypanosoma cruzi is a family of sialidases.

Kahn

Colbert

Wallace

et al. 1991

Proc. Natl. Acad. Sci. U.S.A.

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“…The vector used, SV93 (see Materials and Methods), is very similar to SV103, described previously (38), except for restriction endonuclease sites available for cloning insert cDNAs. The G/C tails were removed from the 5' end (mRNA sense) of the cDNA of RNA segment 6 (pBNA1 [49]) by controlled nuclease Bal 31 and restriction endonuclease digestions. Two deletions were used in the experiments described here.…”

Section: Resultsmentioning

confidence: 99%

Determination of the orientation of an integral membrane protein and sites of glycosylation by oligonucleotide-directed mutagenesis: influenza B virus NB glycoprotein lacks a cleavable signal sequence and has an extracellular NH2-terminal region.

Williams¹,

Lamb²

1986

Mol. Cell. Biol.

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The membrane orientation of the NB protein of influenza B virus, a small (Mr,,000) glycoprotein with a single internal hydrophobic domain, was investigated by biochemical and genetic means. Cell fractionation and protein solubility studies indicate NB is an integral membrane protein, and NB has been shown to be a dimer under nonreducing conditions. Treatment of infected-cell surfaces with proteinase K and endoglycosidase F and immunoprecipitation with a site-specific antibody suggests that the 18-amino-acid NH2-terminal region of NB is exposed at the cell surface. Oligonucleotide-directed mutagenesis to eliminate each of the four potential sites of N-linked glycosylation and expression of the mutant NB proteins in eucaryotic cells suggest that the two sites adjacent to the NH2 terminus are glycosylated. This provides further evidence that NB, which lacks a cleavable NH2-terminal signal sequence, has an exposed NH2 terminus at the cell surface.In eucaryotic cells, glycoproteins are either translocated completely across the membrane into the lumen of the endoplasmic reticulum for soluble proteins destined for secretion or they are asymmetrically integrated into distinct cellular membranes. Integral membrane proteins may span the membrane once or more with the NH2 and COOH termini of the polypeptide chain on either side of the bilayer. These proteins are anchored in membranes by a membranespanning domain which is generally found to consist of 20 or more hydrophobic or uncharged amino acids. It has been established that the orientation of an integral membrane protein is absolute and is maintained regardless of the final destination of the protein (e.g., in the plasma membrane) (reviewed in references 3 and 54). Similarly, the addition of asparagine N-linked carbohydrate to an integral membrane protein is also asymmetric and occurs in the lumen of endoplasmic reticulum vesicles at the amino acid sequence Asn-X-Ser/Thr (reviewed in reference 17). However, determination of the transmembrane orientation and location of the precise sites used for addition of carbohydrate by peptide analysis are often difficult.We have been interested in examining properties of a glycoprotein, NB, of influenza B virus which circumstantial evidence indicated was an integral membrane protein. In the course of these studies we developed a method, based on site-specific mutagenesis and expression of mutant cDNAs in eucaryotic cells, that enabled us to determine the orientation of the protein in membranes and the precise sites of carbohydrate addition.Influenza B virus NB glycoprotein (100 amino acids) is translated from a bicistronic mRNA derived from RNA segment 6 that also encodes the neuraminidase (NA) glycoprotein by using overlapping reading frames (28,48). The first AUG codon in the mRNA is used for the initiation of NB and the second AUG codon, separated from the first AUG codon by four nucleotides, is used to initiate NA. NB * Corresponding author.

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“…In each of the six segments for which sequences have been reported, the protein coding region is flanked by noncoding sequences (2)(3)(4)(5)(6)(7). Each segment has 30-60 noncoding nucleotides at the 3' terminus and 30-100 noncoding nucleotides at the 5' terminus.…”

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confidence: 99%

Segment-specific and common nucleotide sequences in the noncoding regions of influenza B virus genome RNAs.

Stoeckle¹,

Shaw²,

Choppin³

1987

Proc. Natl. Acad. Sci. U.S.A.

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The nucleotide sequences of the 3' noncoding regions of all eight segments of influenza B virus RNA and the sequences of the 5' noncoding regions of segments 4-8 were determined in virus strains isolated over a period of 40 years. Nearly complete conservation of the noncoding sequences was found. Nine nucleotides at the 3' termini and 11 nucleotides at the 5' termini were common to all segments examined. In the region immediately adjacent to the common 3' terminal region, the nucleotides were specific for each segment and these segment-specific sequences were conserved in all strains examined.

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Complete nucleotide sequence of the neuraminidase gene of influenza B virus.

Cited by 72 publications

References 27 publications

The major 85-kDa surface antigen of the mammalian-stage forms of Trypanosoma cruzi is a family of sialidases.

The major 85-kDa surface antigen of the mammalian-stage forms of Trypanosoma cruzi is a family of sialidases.

Determination of the orientation of an integral membrane protein and sites of glycosylation by oligonucleotide-directed mutagenesis: influenza B virus NB glycoprotein lacks a cleavable signal sequence and has an extracellular NH2-terminal region.

Segment-specific and common nucleotide sequences in the noncoding regions of influenza B virus genome RNAs.

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