Biomedical subjects

C Signäs

Publications and source records attributed to C Signäs.

9 recordsLinked to original sources

PubMed1994

A fibronectin-binding protein from Streptococcus equisimilis: characterization of the gene and identification of the binding domain.

We have cloned and characterized a gene, fnb, from S. equisimilis, encoding a fibronectin-binding protein, FnB. A genomic library containing chromosomal DNA from S. equisimilis strain Se165 in the pUC18 vector in E. coli TG1 was screened using a DNA fragment of the gene fnbB from S. dysgalactiae strain S2 as probe. The complete gene was sequenced. The molecular mass of the protein, calculated from the deduced amino acid sequence is 120 kDa, which coincides with that determined by gel electrophoresis and Western blotting of the gene product. The fibronectin-binding activity was localized to a region of three repeated units, each 36 amino acids long. The COOH-terminal part of FnB from S. equisimilis, including the repeated Fn-binding domain, is very similar to the corresponding part of FnBB from S. dysgalactiae, indicating a common origin of the regions encoding Fn-binding activity of the respective genes.

Adhesins, Bacterial↗

PubMed1993

Two different genes coding for fibronectin-binding proteins from Streptococcus dysgalactiae. The complete nucleotide sequences and characterization of the binding domains.

The binding of Streptococcus dysgalactiae to fibronectin involves fibronectin-binding protein(s) present on the bacterial surface. Previously, we reported the cloning of two different genes coding for cell-wall-associated fibronectin-binding proteins from S. dysgalactiae strain S2 [Lindgren, P.-E., Speziale, P., McGavin, M. J., Monstein, H.-J., Höök, M., Visai, L., Kostiainen, T., Bozzini, S. & Lindberg, M. (1992) J. Biol. Chem. 267, 1924-1931]. The two genes, fnbA and fnbB, have now been sequenced and the primary amino acid sequences of the two fibronectin-binding proteins, FnBA and FnBB, have been deduced. The two proteins have predicted molecular masses of 117 kDa and 122 kDa, respectively, and are organized in a similar way. The fibronectin-binding activities are localized in repeated motifs, 32-37 amino acids long, in the COOH-terminal regions of the proteins. The two fibronectin-binding proteins have heterologous amino acid sequences, except for the COOH-terminal ends which include the fibronectin-binding repeats. The fibronectin-binding regions of the genes have been fused to IgG-binding domains of protein A, utilizing the IgG-binding capacity of the resulting fusion proteins, to facilitate isolation of the fibronectin-binding domains.

Adhesins, Bacterial↗

PubMed1991

Two different genes encode fibronectin binding proteins in Staphylococcus aureus. The complete nucleotide sequence and characterization of the second gene.

A gene encoding a fibronectin binding protein (FnBP) has recently been isolated and sequenced from Staphylococcus aureus strain 8325-4. In the same bacterial strain, 682 bp downstream to the stop codon of this gene (fnbA), a second gene termed fnbB has not been discovered, encoding another FnBP (FnBPB). The two genes show in large parts striking sequence homologies. The complete amino acid sequence encoded by fnbB has been deduced and compared to that deduced from fnbA. In FnBPB a stretch of 66 amino acids downstream to the signal peptide has 75% identity with the corresponding region in FnBPA. At the C-terminal site another 394 amino acid stretch is almost identical in both gene products. This stretch contains the 38 amino acid long D repeats, the wall spanning Wr repeats and the hydrophobic membrane spanning domain. In FnBPA each of the three D repeats has been identified as a fibronectin binding structure. These structures are highly conserved in FnBPB and most likely represent the major Fn-binding domain of this protein. However, a subclone of gene fnbB lacking the coding region for the D repeats also clearly expresses fibronectin binding activity. This additional binding site is so far unique for FnBPB and interacts like the D domains with the N-terminal 24-31-kDa fragment of fibronectin. The purified recombinant FnBP fragment (not containing the D repeats) completely inhibits the binding of fibronectin to whole cells of S. aureus.

Amino Acid Sequence↗

PubMed1989

Nucleotide sequence of the gene for a fibronectin-binding protein from Staphylococcus aureus: use of this peptide sequence in the synthesis of biologically active peptides.

Binding of cells of Staphylococcus aureus to fibronectin, which may represent a mechanism of host tissue adherence, involves a fibronectin-receptor protein present on the bacterial surface. Cloning of a gene coding for a staphylococcal fibronectin-binding protein and construction of a fusion protein with fibronectin-binding properties was previously reported from our laboratory. We have now sequenced the gene and deduced a primary sequence of the fibronectin-binding protein. The protein resembles other cell-wall-associated proteins on Gram-positive bacteria in that it (i) appears to be anchored in the cell membrane via its C-terminal end, (ii) contains a proline-rich repeating unit outside the membrane anchor, and (iii) contains a long (36-amino acid) signal sequence at the N terminus. The fibronectin-binding activity has been localized to a domain composed of a 38-amino acid unit repeated completely three times and partially a fourth time; the identity between the three 38-amino acid sequences varies from 42 to 87%. Three synthetic peptides mimicking the structure of each 38-amino acid unit were constructed. All three peptides interacted with fibronectin, as indicated by their ability to inhibit binding of fibronectin to staphylococcal cells, whereas an unrelated 37-amino acid peptide showed no inhibitory activity.

Amino Acid Sequence↗

PubMed1987

Cloning and expression of the gene for a fibronectin-binding protein from Staphylococcus aureus.

The gene encoding the fibronectin-binding protein (FNBP) from Staphylococcus aureus strain 8325-4 was isolated from a gene bank in pBR322. The original clone, containing a 6.5-kb insert, gave a functional product present in the periplasm of Escherichia coli. Analysis of polypeptides isolated after affinity chromatography on fibronectin-Sepharose followed by ion-exchange chromatography revealed two gene products, 87 and 165 kd in mol. wt. The amino acid compositions of these two polypeptides and a native FNBP from S. aureus strain Newman were very similar. Antibodies raised against the native FNBP from strain Newman precipitated the 125I-labelled 165-kd polypeptide, and unlabeled 165- and 87-kd polypeptides as well as native FNBP inhibited the immunoprecipitation reactions. The region of the fnbp-gene encoding the fibronectin-binding activity has been identified and subcloned in an expression vector based on the staphylococcal protein A gene. The resulting product in E. coli is an extracellular fusion protein consisting of two IgG-binding domains of protein A followed by a fibronectin-binding region. The fusion protein binds to fibronectin and completely inhibits the binding of fibronectin to intact cells of S. aureus.

Cloning, Molecular↗

PubMed1986

Region E3 of human adenoviruses; differences between the oncogenic adenovirus-3 and the non-oncogenic adenovirus-2.

The nucleotide sequence of a 4379-bp-long DNA segment, located between map coordinates 76.5 and 89.2 in the Ad3 genome, was established. The segment includes the entire early transcription unit 3 (E3) and the 3'-part of the gene for the late polypeptide pVIII. The established sequence was compared to the sequence of the corresponding region in the Ad2 genome [Hérissé et al., Nucl. Acids Res. 8, (1980) 2173-2192; Hérissé and Galibert, Nucl. Acids Res. 9, (1981) 1229-1249]. Although Ad2 and Ad3 belong to different serological and oncogenic subgroups, their E3 regions are well conserved (55-60% homology). In total, the E3 region of Ad3 appears to encode eight to nine different polypeptides many of which are likely to be membrane-associated. The most conspicuous difference between the E3 regions of Ad2 and Ad3 is the presence of a 950-bp-long A + T-rich insert in the Ad3 sequence. This insert contains two open reading frames, each encoding a polypeptide with a predicted Mr of about 20,000. The mRNAs encoding these novel polypeptides were identified by S1 nuclease analysis.

Adenoviruses, Human↗

PubMed1985

Adenovirus 3 fiber polypeptide gene: implications for the structure of the fiber protein.

The nucleotide sequence of a 1,330-base-pair-long DNA segment located between map coordinates 88.5 and 92.3 in the adenovirus type 3 (Ad3) genome was determined. Transcripts from the r-strand of the region were mapped by S1 nuclease analysis and by in vitro translation of RNA, selected by filter hybridization. The results revealed that the sequenced region encodes the Ad3 fiber polypeptide with a molecular weight of 34,800. A comparison between the predicted amino acid sequences of the Ad3 and the Ad2 fiber polypeptides revealed that they have almost identical secondary structures, consisting of a tail, a shaft, and a knob. A striking difference between Ad2 and Ad3 fibers was that the shaft of the Ad3 fiber was significantly shorter, containing only 6 repeat units compared with 22 in the Ad2 fiber. The secondary structure suggests that the fiber is a dimeric structure, as proposed earlier (N.M. Green, N.G. Wrigley, W.C. Russell, S.R. Martin, and A.D. McLachlan, EMBO J. 2:1357-1365, 1983), with the size of the polypeptide determining the length of the fiber protein.

Adenoviridae↗

PubMed1982

An adenovirus glycoprotein binds heavy chains of class I transplantation antigens from man and mouse.

The successful killing of virus-infected cells by cytotoxic T lymphocytes (CTL) is dependent on the recognition of both a viral product and class I antigens of the major histocompatibility complex (MHC) on the infected cell surface. Whether these two entities are found independently on the cell surface and therefore recognized by two different CTL receptors, or whether they are associated together and can therefore be recognized by a single receptor is not known. The association between an adenovirus-encoded glycoprotein expressed on the cell surface early after infection and class I antigens has been investigated and it has been found that antisera against class I antigens can co-precipitate the antigen and the viral glycoprotein from an adenovirus-transformed cell line from the Hooded-Lister rat strain. We show here by in vitro affinity chromatography and in vivo immunoprecipitation that the viral glycoprotein specifically binds to the heavy chain of class I antigens in both man and mouse.

Adenoviridae↗

PubMed1979

Purification and characterization of an early glycoprotein from adenovirus type 2-infected cells.

An adenovirus type 2 early glycoprotein with an apparent molecular weight of 19,000 (E19K) in sodium dodecyl sulfate-polyacrylamide gels has been extensively purified. Purification involved detergent solubilization of membrane fractions from infected cells, followed by affinity chromatography on a lectin column and DEAE-Sephadex chromatography. The purified material contained three polypeptides (E40K, E19K, E17.5K), with approximately 90% of the material in the E19K moiety. All three polypeptides yielded identical tryptic peptide maps. The E19K polypeptide contained glucosamine as revealed by [3H]glucosamine labeling of infected cells and amino acid analysis of the purified protein. Immunoprecipitation with a monospecific antiserum showed that the E19K polypeptide started to be synthesized at 2 h, with a maximal rate at 4 h after infection. It was also synthesized at a low rate late in the infectious cycle (12 to 24 h postinfection). Immunoprecipitation from three adenovirus type 2-transformed hamster embryo cell lines and two adenovirus type 2-transformed rat cell lines revealed that one of the hamster cell lines (ad2HE4) and one of the rat cell lines (A2T2C4) expressed this protein.

Adenoviruses, Human↗