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Sequence and variability of the 5.8S and 26S rRNA genes of Pneumocystis carinii.

ABSTRACT: The sequence of the coding region of the rRNA operon of rat-derived Pneumocystis carinii has been completed, including the genes for 5.8S and 26S rRNA. These genes show homology to the rRNA genes of yeast, and an apparent group I self-splicing intron is present in the 26S rRNA gene. Like a similar intron in the 16S rRNA gene, this intron is in a phylogenetically conserved region. Variation in the 26S rRNA sequence was noted between P. carinii organisms isolated from two different sources.

SUBMITTER: Liu Y

PROVIDER: S-EPMC334029 | biostudies-other | 1992 Jul

REPOSITORIES: biostudies-other

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Sequence and variability of the 5.8S and 26S rRNA genes of Pneumocystis carinii.

Liu Y Y Rocourt M M Pan S S Liu C C Leibowitz M J MJ

Nucleic acids research 19920701 14

The sequence of the coding region of the rRNA operon of rat-derived Pneumocystis carinii has been completed, including the genes for 5.8S and 26S rRNA. These genes show homology to the rRNA genes of yeast, and an apparent group I self-splicing intron is present in the 26S rRNA gene. Like a similar intron in the 16S rRNA gene, this intron is in a phylogenetically conserved region. Variation in the 26S rRNA sequence was noted between P. carinii organisms isolated from two different sources. ...[more]

PMID: 1641341

Similar Datasets

Internal transcribed spacer regions of rRNA genes of Pneumocystis carinii from monkeys.

Project description:Analysis of sequence variations among isolates of Pneumocystis carinii f. sp. macacae from 14 Indian rhesus monkeys (Macaca mulatta) at the internal transcribed spacer (ITS) regions of the nuclear rRNA gene was undertaken. Like those from P. carinii f. sp. hominis, the ITS sequences from various P. carinii f. sp. macacae isolates were not identical. Two major types of sequences were found. One type of sequence was shared by 13 isolates. These 13 sequences were homologous but not identical. Variations were found at 13 of the 180 positions in the ITS1 region and 28 of the 221 positions in the ITS2 region. These sequence variations were not random but exhibited definite patterns when the sequences were aligned. According to this sequence variation, ITS1 sequences were classified into three types and ITS2 sequences were classified into five types. The remaining specimen had ITS1 and ITS2 sequences substantially different from the others. Although some specimens had the same ITS1 or ITS2 sequence, all 14 samples exhibited a unique whole ITS sequence (ITS1 plus ITS2). The 5.8S rRNA gene sequences were also analyzed, and only two types of sequences that differ by only one base were found. Unlike P. carinii f. sp. hominis infections in humans, none of the monkey lung specimens examined in this study were found to be infected by more than one type of P. carinii f. sp. macacae. These results offer insights into the genetic differences between P. carinii organisms which infect distinct species.

| S-EPMC96091 | biostudies-literature

Update on Pneumocystis carinii f. sp. hominis typing based on nucleotide sequence variations in internal transcribed spacer regions of rRNA genes.

Project description:Pneumocystis carinii f. sp. hominis isolates from 207 clinical specimens from nine countries were typed based on nucleotide sequence variations in the internal transcribed spacer regions I and II (ITS1 and ITS2, respectively) of rRNA genes. The number of ITS1 nucleotides has been revised from the previously reported 157 bp to 161 bp. Likewise, the number of ITS2 nucleotides has been changed from 177 to 192 bp. The number of ITS1 sequence types has increased from 2 to 15, and that of ITS2 has increased from 3 to 14. The 15 ITS1 sequence types are designated types A through O, and the 14 ITS2 types are named types a through n. A total of 59 types of P. carinii f. sp. hominis were found in this study.

| S-EPMC104617 | biostudies-literature

Typing of Pneumocystis carinii strains that infect humans based on nucleotide sequence variations of internal transcribed spacers of rRNA genes.

Project description:Small portions of the 18S and the 26S rRNA genes, the entire 5.8S rRNA gene, and internal transcribed spacers ITS1 and ITS2 (located between the 18S and 5.8S rRNA genes and between the 5.8S and 26S rRNA genes, respectively) of Pneumocystis carinii that infect humans were cloned and sequenced. The nucleotide sequences of the 18S, 5.8S, and 26S rRNA genes determined in the study were approximately 90% homologous to those of P. carinii that infect rats, while the sequences of ITS1 and ITS2 of P. carinii from the two different hosts were only 60% homologous. The 18S, 5.8S, and 26S rRNA gene sequences of P. carinii from 15 patient specimens were determined and were found to be identical to each other, whereas the ITS sequences were found to be variable. With the observed sequence variation, it was possible to classify the ITS1 sequences into two types and the ITS2 sequences into three types. P. carinii strains that had the same type of ITS1 sequence could have a different type of ITS2 sequence. On the basis of the sequence types of the two ITS regions, P. carinii from the 15 patients were classified into four groups. P. carinii from three patient specimens were found to contain two different ITS sequence patterns. More surprisingly, one additional specimen was found to have one ITS sequence typical of P. carinii isolates that infect humans and another typical of P. carinii isolates that infect rats. The studies indicate that it is possible to type P. carinii strains on the basis from one patient, suggesting that coinfection with more than one strain of P. carinii may occur in the same patient.

| S-EPMC264199 | biostudies-other

Variation and in vitro splicing of group I introns in rRNA genes of Pneumocystis carinii.

Project description:The sequences of the rRNA genes of Pneumocystis carinii from rat and human sources demonstrate three distinct genotypes based on the group I introns present in these genes. One rat isolate (Pc1) contains such introns in its 16S and 26S rRNA genes, while another rat isolate (Pc2) and a human isolate (Pc3) only contain an intron in the 26S rRNA gene. The four introns all catalyze their own excision from RNA transcripts, and this reaction is inhibited by the anti-pneumocystis drug pentamidine and its analogues. Although they differ in sequence, they are more similar to one another than to group I introns found in other eukaryotic microbes.

| S-EPMC309541 | biostudies-other

Signal transduction in Pneumocystis carinii: characterization of the genes (pcg1) encoding the alpha subunit of the G protein (PCG1) of Pneumocystis carinii carinii and Pneumocystis carinii ratti.

Project description:Pneumocystis carinii is a eukaryotic organism that causes pneumonia in immunocompromised hosts. The cell biology and life cycle of the organism are poorly understood primarily because of the lack of a continuous in vitro cultivation system. These limitations have prevented investigation of the organism's infectious cycle and hindered the rational development of new antimicrobial therapies and implementation of measures to prevent exposure to the organism or transmission. The interaction of P. carinii with its host and its environment may be critical determinants of pathogenicity and life cycle. Signal transduction pathways are likely to be critical in regulating these processes. G proteins are highly conserved members of the pathways important in many cellular events, including cell proliferation and environmental sensing. To characterize signal transduction pathways in P. carinii, we cloned a G-protein alpha subunit (G-alpha) of P. carinii carinii and P. carinii ratti by PCR amplification and hybridization screening. The gene encoding the G-alpha was present in single copy on a 450-kb chromosome of P.c. ratti. The 1,062-bp G-alpha open reading frame is interrupted by nine introns. The predicted polypeptide showed 29 to 53% identity with known fungal G-alpha proteins with greatest homology to Neurospora crassa Gna-2. Northern (RNA) blot analysis and immunoprecipitation demonstrated expression of the G-alpha mRNA and protein P. carinii isolated from heavily infected animals. Some alteration in the level of transcription was noted in short-term maintenance in starvation or rich medium. Characterization of signal transduction in P. carinii will permit a better understanding of the reproductive capacity and other cellular processes in this family or organisms that cannot be cultured continuously.

| S-EPMC173824 | biostudies-other

Pneumocystis carinii

Project description:Pathogenic fungus that causes pneumonia in rats

| PRJNA9515 | ENA

Analysis of Pneumocystis carinii introns.

Project description:Pneumocystis carinii is an ascomycete phylogenetically related to Schizosaccharomyces pombe. Little is known about gene regulation in P. carinii. The removal of introns from pre-mRNA requires spliceosomal recognition of the intron-exon boundary. In S. pombe and higher eukaryotes, this boundary and a branch site within the intron are conserved. We recently demonstrated that P. carinii cdc2 cDNA can complement S. pombe containing conditional mutations of cdc2, an essential gene involved in cell cycle regulation. We next tested whether P. carinii genomic cdc2 (with six introns) could also complement S. pombe cdc2 mutants and found genomic sequences incapable of this activity. Reverse transcriptase PCR confirmed the inability of the S. pombe cdc2 mutants to splice the P. carinii genomic cdc2. Analysis of 83 introns from 19 P. carinii protein-encoding genes demonstrated that the sequence GTWWDW functions as a donor consensus in P. carinii, whereas YAG serves as an acceptor consensus. These sequences are similar in S. pombe; however, a branch site sequence was not found in the P. carinii genes studied.

| S-EPMC97006 | biostudies-literature

Chitinases in Pneumocystis carinii pneumonia.

Project description:Pneumocystis pneumonia remains an important complication of immune suppression. The cell wall of Pneumocystis has been demonstrated to potently stimulate host inflammatory responses, with most studies focusing on β-glucan components of the Pneumocystis cell wall. In the current study, we have elaborated the potential role of chitins and chitinases in Pneumocystis pneumonia. We demonstrated differential host mammalian chitinase expression during Pneumocystis pneumonia. We further characterized a chitin synthase gene in Pneumocystis carinii termed Pcchs5, a gene with considerable homolog to the fungal chitin biosynthesis protein Chs5. We also observed the impact of chitinase digestion on Pneumocystis-induced host inflammatory responses by measuring TNFα release and mammalian chitinase expression by cultured lung epithelial and macrophage cells stimulated with Pneumocystis cell wall isolates in the presence and absence of exogenous chitinase digestion. These findings provide evidence supporting a chitin biosynthetic pathway in Pneumocystis organisms and that chitinases modulate inflammatory responses in lung cells. We further demonstrate lung expression of chitinase molecules during Pneumocystis pneumonia.

| S-EPMC3913163 | biostudies-literature

Genetic diversity of Pneumocystis carinii f. sp. hominis based on variations in nucleotide sequences of internal transcribed spacers of rRNA genes.

Project description:A variety of genes have been used to type Pneumocystis carinii. In the present study, nucleotide sequence variations in the ITS1 and ITS2 internal transcribed spacer (ITS) regions of the rRNA genes were used to type Pneumocystis carinii f. sp. hominis DNA obtained from the lungs of 60 human immunodeficiency virus-infected individuals. These regions were amplified by PCR, cloned, and sequenced. Multibase polymorphisms were identified among samples. Several new genotypes are reported on the basis of the nucleotide sequence variations at previously unreported positions of both the ITS1 and the ITS2 regions. Twelve new ITS1 sequences were observed, in addition to the nine sequence types reported previously. The most common was type E, which was observed in 60.5% of the samples. The sequence variations in the ITS1 region were mainly located at positions 5, 12, 23, 24, 45, 53, and 54. Sixteen new ITS2 types were also identified, in addition to the 13 types reported previously. The most common was type g (26.6%). The sequences of the ITS2 regions in most specimens were different from the previously published sequence at bases 120 and 166 through 183. The most common variations observed were deletions at positions 177 through 183. The presence of more than one sequence type in some patients (60%) suggested the occurrence of coinfection with multiple P. carinii strains. The genetic polymorphism observed demonstrates the degree of diversity of Pneumocystis strains that infect humans. Furthermore, the high degree of polymorphism suggests that these genes are evolving faster than other genes. Consequently, the sequence information derived is useful for purposes such as examination of the potential of person-to-person transmission and recurrent infections but perhaps not for other genotyping applications that rely on more stable genetic loci.

| S-EPMC140386 | biostudies-literature

Gene arrays at Pneumocystis carinii telomeres.

Project description:In the fungus Pneumocystis carinii, at least three gene families (PRT1, MSR, and MSG) have the potential to generate high-frequency antigenic variation, which is likely to be a strategy by which this parasitic fungus is able to prolong its survival in the rat lung. Members of these gene families are clustered at chromosome termini, a location that fosters recombination, which has been implicated in selective expression of MSG genes. To gain insight into the architecture, evolution, and regulation of these gene clusters, six telomeric segments of the genome were sequenced. Each of the segments began with one or more unique genes, after which were members of different gene families, arranged in a head-to-tail array. The three-gene repeat PRT1-MSR-MSG was common, suggesting that duplications of these repeats have contributed to expansion of all three families. However, members of a gene family in an array were no more similar to one another than to members in other arrays, indicating rapid divergence after duplication. The intergenic spacers were more conserved than the genes and contained sequence motifs also present in subtelomeres, which in other species have been implicated in gene expression and recombination. Long mononucleotide tracts were present in some MSR genes. These unstable sequences can be expected to suffer frequent frameshift mutations, providing P. carinii with another mechanism to generate antigen variation.

| S-EPMC1449779 | biostudies-literature

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