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J R Stringer

Publications and source records attributed to J R Stringer.

89 records · Page 5Linked to original sources
PubMedDate not supplied

Molecular genetic distinction of Pneumocystis carinii from rats and humans.

Pneumocystis carinii from rats and from humans were compared with respect to electrophoretic karyotype, presence of DNA sequences known to be repeated in rat-derived P. carinii, overall DNA sequence homology, and the sequences at two genetic loci. The organisms from each host species were different in each respect. Neither of two repeated DNAs from rat-derived P. carinii was found in the genome of human-derived organisms, and total DNA from rat-derived P. carinii failed to hybridize to human-derived P. carinii DNA. The sequences of the alpha-tubulin genes from the two P. carinii were strikingly different and the base composition of the alpha-tubulin gene from rat-derived P. carinii was rich in adenine and thymine, while the base composition of this gene from human-derived P. carinii was rich in guanine and cytosine. The sequence from the 18S rRNA gene of human-derived P. carinii was twice as divergent from that of rat-derived P. carinii as the sequence from the corresponding region of Candida albicans was from that of Candida tropicalis. These data show that rats and humans can harbor distinct types of P. carinii that are sufficiently different to suggest that P. carinii from the two hosts could be different species.

Amino Acid Sequence↗
PubMedDate not supplied

Genes encoding antigenic surface glycoproteins in Pneumocystis from humans.

Pneumocystis is a eukaryotic microbe that causes pneumocystosis, an AIDS-associated pneumonia. Pneumocystosis also occurs in many other mammalian species, and animal-derived organisms have been extensively utilized in Pneumocystis research. Pneumocystis from diverse hosts contain a large glycoprotein (gpA/MSG) on the surface. Antibodies elicited against gpA/MSG of Pneumocystis from humans sometimes cross-react with epitopes on proteins of similar size from Pneumocystis from other host species. Here we report the isolation and partial sequence of two presumptive gpA/MSG genes from human-derived Pneumocystis. The cloned human-derived Pneumocystis gpA/MSG genes and predicted peptides were different from those previously isolated from Pneumocystis from rats and ferrets. The genome of human-derived Pneumocystis contained multiple copies of sequences related to the two cloned gpA/MSG genes.

AIDS-Related Opportunistic Infections↗
PubMedDate not supplied

A tandem repeat of rat-derived Pneumocystis carinii genes encoding the major surface glycoprotein.

A fragment from the genome of rat-derived Pneumocystis carinii was found to contain two MSG genes arranged as a direct repeat. The sequences from one gene (MSG B), the region between the two genes, and part of the second gene (MSG A) were determined. The two MSG genes were not identical in sequence. The open reading frames of MSG A and MSG B encode non-identical proteins, both of which are similar to that encoded by a previously published cDNA. The MSG B gene sequence showed no evidence of introns. The 5' and 3' untranslated regions of the MSG gene pair were highly conserved, but the regions immediately upstream of the open reading frames of MSG A and B were different from the region upstream of a previously characterized MSG cDNA. Primers designed to extend upstream of the 5' end of MSG and downstream of the 3' end of MSG were used in a polymerase chain reaction with total genomic P. carinii DNA as template. Presumptive intergenic amplification products from this reaction were cloned and sequenced. The sequences of these regions were similar but distinct, indicating that tandem arrangement of MSG genes is a common organizational motif.

Amino Acid Sequence↗
PubMedDate not supplied

Transcription factor genes from rat Pneumocystis carinii.

Genes encoding the TFIID TATA-box binding protein (TBP) from two probable species of rat Pneumocystis carinii (prototype and variant) were sequenced. The two P. carinii TBP gene sequences were 91% identical to each other, and 65-77% identical to TBP genes from other species. A cDNA from one of the two P. carinii TBP genes was sequenced, which showed that four small introns resided in identical positions within the TBP genes from the prototype and variant rat P. carinii. Conservation of the 180 amino acids that constitute the conserved core of TBP was 97% between the P. carinii TBP, which were 95% and 97% identical to conserved core sequences of TBP from Saccharomyces cerevisiae and Schizosaccharomyces pombe respectively.

Amino Acid Sequence↗
PubMedDate not supplied

Cloning and characterization of an ATPase gene from Pneumocystis carinii which closely resembles fungal H+ ATPases.

A gene encoding a P-type cation translocating ATPase was cloned from a genomic library of rat-derived Pneumocystis carinii. The nucleotide sequence of the gene contains a 2781 base-pair open reading frame that is predicted to encode a 101,401 dalton protein composed of 927 amino acids. The P. carinii ATPase protein (pcal) is 69-75% identical when compared with eight proton pumps from six fungal species. The Pneumocystis ATPase is less than 34% identical to ATPase proteins from protozoans, vertebrates or the Ca++ ATPases of yeast. The P. carinii ATPase contains 115 of 121 residues previously identified as characteristic of H+ ATPases. Alignment of the Pneumocystis and fungal proton pumps reveals five homologous domains specific for fungal H+ ATPases.

Adenosine Triphosphatases↗
PubMedDate not supplied

Genetic variation in Pneumocystis carinii isolates from different geographic regions: implications for transmission.

To study transmission patterns of Pneumocystis carinii pneumonia (PCP) in persons with AIDS, we evaluated P. carinii isolates from patients in five U.S. cities for variation at two independent genetic loci, the mitochondrial large subunit rRNA and dihydropteroate synthase. Fourteen unique multilocus genotypes were observed in 191 isolates that were examined at both loci. Mixed infections, accounting for 17.8% of cases, were associated with primary PCP. Genotype frequency distribution patterns varied by patients' place of diagnosis but not by place of birth. Genetic variation at the two loci suggests three probable characteristics of transmission: that most cases of PCP do not result from infections acquired early in life, that infections are actively acquired from a relatively common source (humans or the environment), and that humans, while not necessarily involved in direct infection of other humans, are nevertheless important in the transmission cycle of P. carinii f. sp. hominis.

AIDS-Related Opportunistic Infections↗
PubMedDate not supplied

Expression cloning of Pneumocystis carinii antigens.

We undertook expression cloning of Pneumocystis carinii antigens to overcome the difficulties encountered in purification of these antigens. Using monoclonal antibodies to the P. carinii gp120 antigen and polyclonal rabbit antiserum to rat-derived P. carinii, we have isolated cDNA clones encoding immunoreactive moieties. A cDNA clone encoding the 3' portion of a 45-55 kDa antigen of rat-derived P. carinii, was the most abundant clone isolated. The peptide encoded by this cDNA has a novel sequence with a repeated motif rich in glutamic acid residues. Affinity-purified antibodies to this peptide reacted with the 45-55 kDa band of rat-derived P. carinii. The fusion protein was recognized by serum antibodies from rats with natural exposure to P. carinii. The production of this recombinant protein should allow more detailed studies of the host-parasite relationship of this important opportunistic infection.

Amino Acid Sequence↗
PubMedDate not supplied

PCR amplification of DNA sequences from the transcription factor IID and cation transporting ATPase genes in Pneumocystis carinii.

Oligonucleotide primers were used to amplify DNA sequences from a plasma membrane cation transporting ATPase gene and a transcription factor IID (TFIID) gene from Pneumocystis carinii genomic DNA. The entire P. carinii ATPase gene was cloned from a genomic library by hybridization to the PCR-amplified DNA product. The nucleotide sequence of the gene contained a 2,799 base-pair open reading frame that encoded a 102,274 dalton protein composed of 933 amino acids. The P. carinii ATPase protein was 69-74% identical to four fungal proton pumps but less than 35% identical to protozoan and mammalian cation transporting ATPase genes or the Ca++ ATPases of Saccharomyces. The nucleotide sequence of a portion of the TFIID gene could be translated to produce a peptide of 53 amino acids in two regions of the sequence, interrupted by a 45 bp intron. The predicted TFIID amino acid sequence was identical to yeast TFIID genes in this region.

Adenosine Triphosphatases↗