101
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Huang L, Friedly J, Morris AM, Carter JL, Turner JR, Merrifield C, Navin TR, Beard CB. Pneumocystis carinii dihydropteroate synthase genotypes in HIV-infected persons residing in San Francisco: possible implications for disease transmission. J Eukaryot Microbiol 2002; Suppl:137S-138S. [PMID: 11906028 DOI: 10.1111/j.1550-7408.2001.tb00487.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- L Huang
- Division of Pulmonary and Critical Care Medicine, San Francisco General Hospital, University of California San Francisco, 94110, USA.
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102
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Huang L, Morris AM, Beard CB. Pneumocystis carinii dihydropteroate synthase mutations and treatment with sulfa or sulfone regimens: a proposal for standardized definitions for clinical evaluation. J Eukaryot Microbiol 2002; Suppl:180S-181S. [PMID: 11906054 DOI: 10.1111/j.1550-7408.2001.tb00510.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- L Huang
- Division of Pulmonary and Critical Care Medicine, San Francisco General Hospital, University of California San Francisco, 94110, USA.
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103
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Ma L, Jia Q, Kovacs JA. Development of a yeast assay for rapid screening of inhibitors of human-derived Pneumocystis carinii dihydrofolate reductase. Antimicrob Agents Chemother 2002; 46:3101-3. [PMID: 12183283 PMCID: PMC127411 DOI: 10.1128/aac.46.9.3101-3103.2002] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Human-derived Pneumocystis carinii dihydrofolate reductase (DHFR) was expressed in a Saccharomyces cerevisiae strain whose growth depends on complementation by this enzyme. We utilized a quantitative assay to measure the sensitivity of this yeast strain to DHFR inhibitors. This assay should be useful for identifying new inhibitors of human-derived P. carinii DHFR.
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Affiliation(s)
- Liang Ma
- Critical Care Medicine Department, Warren Grant Magnuson Clinical Center, National Institutes of Health, Bethesda, Maryland 20892-1662, USA
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104
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Larsen HH, Kovacs JA, Stock F, Vestereng VH, Lundgren B, Fischer SH, Gill VJ. Development of a rapid real-time PCR assay for quantitation of Pneumocystis carinii f. sp. carinii. J Clin Microbiol 2002; 40:2989-93. [PMID: 12149363 PMCID: PMC120631 DOI: 10.1128/jcm.40.8.2989-2993.2002] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A method for reliable quantification of Pneumocystis carinii in research models of P. carinii pneumonia (PCP) that is more convenient and reproducible than microscopic enumeration of organisms would greatly facilitate investigations of this organism. We developed a rapid quantitative touchdown (QTD) PCR assay for detecting P. carinii f. sp. carinii, the subspecies of P. carinii commonly used in research models of PCP. The assay was based on the single-copy dihydrofolate reductase gene and was able to detect <5 copies of a plasmid standard per tube. It was reproducibly quantitative (r = 0.99) over 6 log values for standards containing > or =5 copies/tube. Application of the assay to a series of 10-fold dilutions of P. carinii organisms isolated from rat lung demonstrated that it was reproducibly quantitative over 5 log values (r = 0.99). The assay was applied to a recently reported in vitro axenic cultivation system for P. carinii and confirmed our microscopy findings that no organism multiplication had occurred during culture. For all cultures analyzed, QTD PCR assays showed a decrease in P. carinii DNA that exceeded the expected decrease due to dilution of the inoculum upon transfer. In conclusion, a rapid, sensitive, and reproducible quantitative PCR assay for P. carinii f. sp. carinii has been developed and is applicable to in vivo as well as in vitro systems. The assay should prove useful for conducting studies in which quantification of organism burden or growth assessment is critical, such as in vitro antimicrobic susceptibility testing or in vivo immunopathological experiments.
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Affiliation(s)
- Hans Henrik Larsen
- Department of Laboratory Medicine, Clinical Center, National Institutes of Health, Bethesda, Maryland, USA.
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105
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Giner JL, Zhao H, Beach DH, Parish EJ, Jayasimhulu K, Kaneshiro ES. Comprehensive and definitive structural identities of Pneumocystis carinii sterols. J Lipid Res 2002; 43:1114-24. [PMID: 12091496 DOI: 10.1194/jlr.m200113-jlr200] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Pneumocystis causes a type of pneumonia in immunodeficient mammals, such as AIDS patients. Mammals cannot alkylate the C-24 position of the sterol side chain, nor can they desaturate C-22. Thus, the reactions leading to these sterol modifications are particularly attractive targets for the development of drugs against fungal and protozoan pathogens that make them. In the present study, the definitive structures of 43 sterol molecular species in rat-derived Pneumocystis carinii were elucidated by nuclear magnetic resonance spectroscopy. Ergosterol, Delta(5,7) sterols, trienes, and tetraenes were not among them. Most (32 of the 43) were 24-alkylsterols, products of S-adenosyl-L-methionine:C-24 sterol methyl transferase (SAM:SMT) enzyme activity. Their abundance is consistent with the suggestion that SAM:SMT is highly active in this organism and that the enzyme is an excellent anti-Pneumocystis drug target. In contrast, the comprehensive analysis strongly suggest that P. carinii does not form Delta(22) sterols, thus C-22 desaturation does not appear to be a drug target in this pathogen. The lanosterol derivatives, 24-methylenelanost-8-en-3 beta-ol and (Z)-24-ethylidenelanost-8-en-3 beta-ol (pneumocysterol), previously identified in human-derived Pneumocystis jiroveci, were also detected among the sterols of the rat-derived P. carinii organisms.
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Affiliation(s)
- José-Luis Giner
- Department of Chemistry, State University of New York, ESF, Syracuse, NY 13210, USA
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106
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Kaneshiro ES, Rosenfeld JA, Basselin-Eiweida M, Stringer JR, Keely SP, Smulian AG, Giner JL. The Pneumocystis carinii drug target S-adenosyl-L-methionine:sterol C-24 methyl transferase has a unique substrate preference. Mol Microbiol 2002; 44:989-99. [PMID: 12010494 DOI: 10.1046/j.1365-2958.2002.02932.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Pneumocystis is an opportunistic pathogen that can cause pneumonitis in immunodeficient people such as AIDS patients. Pneumocystis remains difficult to study in the absence of culture methods for luxuriant growth. Recombinant protein technology now makes it possible to avoid some major obstacles. The P. carinii expressed sequence tag (EST) database contains 11 entries of a sequence encoding a protein homologous to S-adenosyl-L-methionine (SAM):C-24 sterol methyl transferase (SMT), suggesting high activity of this enzyme in the organism. We sequenced the erg6 cDNA, identified the putative peptide motifs for the sterol and SAM binding sites in the deduced amino acid sequence and expressed the protein in Escherichia coli. Unlike SAM:SMT from other organisms, the P. carinii enzyme had higher affinities for lanosterol and 24-methylenelanosterol than for zymosterol, the preferred substrate in other fungi. Cycloartenol was not a productive substrate. With lanosterol and 24-methylenelanosterol as substrates, the major reaction products were 24-methylenelanosterol and pneumocysterol respectively. Thus, the P. carinii SAM:SMT catalysed the transfer of both the first and the second methyl groups to the sterol C-24 position, and the substrate preference was found to be a unique property of the P. carinii SAM:SMT. These observations, together with the absence of SAM:SMT among mammals, further support the identification of sterol C-24 alkylation reactions as excellent targets for the development of drugs specifically directed against this pathogen.
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Affiliation(s)
- Edna S Kaneshiro
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH 45221-0006, USA.
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107
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Nimri LF, Moura INS, Huang L, del Rio C, Rimland D, Duchin JS, Dotson EM, Beard CB. Genetic diversity of Pneumocystis carinii f. sp. hominis based on variations in nucleotide sequences of internal transcribed spacers of rRNA genes. J Clin Microbiol 2002; 40:1146-51. [PMID: 11923323 PMCID: PMC140386 DOI: 10.1128/jcm.40.4.1146-1151.2002] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2001] [Revised: 12/10/2001] [Accepted: 01/07/2002] [Indexed: 01/19/2023] Open
Abstract
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.
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Affiliation(s)
- Laila F Nimri
- Centers for Disease Control and Prevention, Atlanta, Georgia, USA.
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108
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Abstract
Although Pneumocystis carinii pneumonia is one of the leading causes of morbidity and mortality among patients with the acquired immunodeficiency syndrome, many questions about its epidemiology and transmission remain unanswered. Whereas traditional theory postulates that the disease results from reactivation of latent infection, recent data suggest that active acquisition of infection, either through environmental exposure or person-to-person transmission, may occur. This review summarizes the current state of knowledge about the epidemiology and transmission of P. carinii and reports on evolving techniques that may improve our understanding of this organism in the future.
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Affiliation(s)
- Alison Morris
- Department of Medicine, San Francisco General Hospital, University of California, San Francisco, CA, USA.
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109
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Visconti E, Ortona E, Mencarini P, Margutti P, Marinaci S, Zolfo M, Siracusano A, Tamburrini E. Mutations in dihydropteroate synthase gene of Pneumocystis carinii in HIV patients with Pneumocystis carinii pneumonia. Int J Antimicrob Agents 2001; 18:547-51. [PMID: 11738342 DOI: 10.1016/s0924-8579(01)00460-5] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The purpose of this study was to determine whether dihydropteroate synthase gene (DHPS) mutations were associated with the failure of sulpha/sulphone drugs used as prophylaxis agents in HIV infected patients. Results suggested that DHPS mutations were significantly associated with failure of anti-Pneumocystis carinii sulphone prophylaxis (P=0.031). An increasing number of mutant P. carinii strains have been isolated from patients no longer having prophylaxis. There was no statistically significant difference in severity or outcome of the pneumonia caused by wild-type or mutant DHPS. Moreover, two of the three patients with mutant P. carinii pneumonia (PCP) were successfully treated with sulpha drugs. We think that P. carinii drug-resistance could be an emerging problem for immunocompromised patients including those with HIV infection.
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Affiliation(s)
- E Visconti
- Department of Infectious Diseases, Università Cattolica del S. Cuore, Largo F. Vito, 1 00168, Rome, Italy
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110
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Ma L, Kovacs JA. Genetic analysis of multiple loci suggests that mutations in the Pneumocystis carinii f. sp. hominis dihydropteroate synthase gene arose independently in multiple strains. Antimicrob Agents Chemother 2001; 45:3213-5. [PMID: 11600382 PMCID: PMC90808 DOI: 10.1128/aac.45.11.3213-3215.2001] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
To determine if mutations in the dihydropteroate synthase (DHPS) gene of Pneumocystis carinii f. sp. hominis arose in a single strain that was subsequently widely disseminated, we examined four genomic regions of 22 P. carinii clinical isolates selected based on the absence or presence of mutations in the DHPS gene. By single-strand conformation polymorphism and DNA sequencing, we found varying genotypes for each of the four regions in isolates with DHPS mutations, suggesting that these mutations occurred independently in multiple strains of P. carinii. This suggests that exposure to sulfa will select for these mutations in diverse strains.
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Affiliation(s)
- L Ma
- Critical Care Medicine Department, Warren Grant Magnuson Clinical Center, National Institutes of Health, Bethesda, Maryland 20892-1662, USA.
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111
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Helweg-Larsen J, Lundgren B, Lundgren JD. Heterogeneity and compartmentalization of Pneumocystis carinii f. sp. hominis genotypes in autopsy lungs. J Clin Microbiol 2001; 39:3789-92. [PMID: 11574620 PMCID: PMC88436 DOI: 10.1128/jcm.39.10.3789-3792.2001] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The extent and importance of genotype heterogeneity of Pneumocystis carinii f. sp. hominis within lungs have not previously been investigated. Two hundred forty PCR clones obtained from respiratory specimens and lung segments from three patients with fatal P. carinii pneumonia were investigated to detect genetic diversity in the internal transcribed spacer (ITS) region of the nuclear rRNA operon, the mitochondrial large-subunit (mtLSU) rRNA gene, and the dihydropteroate synthase-encoding gene. For two of the three examined patients, a mixture of different mtLSU rRNA and ITS genotypes was observed. Not all genotypes present in the lungs at autopsy were detected in the diagnostic respiratory samples. Compartmentalization of specific ITS and mtLSU rRNA sequence types was observed in different lung segments. In conclusion, the interpretation of genotype data and in particular ITS sequence types in the assessment of epidemiological questions should be cautious since genotyping done on respiratory samples cannot a priori be assumed to represent all genotypes present within the lung.
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Affiliation(s)
- J Helweg-Larsen
- Department of Infectious Diseases, Hvidovre University Hospital, Copenhagen, Denmark.
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112
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Navin TR, Beard CB, Huang L, del Rio C, Lee S, Pieniazek NJ, Carter JL, Le T, Hightower A, Rimland D. Effect of mutations in Pneumocystis carinii dihydropteroate synthase gene on outcome of P carinii pneumonia in patients with HIV-1: a prospective study. Lancet 2001; 358:545-9. [PMID: 11520525 DOI: 10.1016/s0140-6736(01)05705-1] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
BACKGROUND Investigators have reported that patients infected with Pneumocystis carinii containing mutations in the DHPS (dihydropteroate synthase) gene have a worse outcome than those infected with P carinii containing wild-type DHPS. We investigated patients with HIV-1 infection and P carinii pneumonia to determine if DHPS mutations were associated with poor outcomes in these patients. METHODS We compared presence of mutations at the DHPS locus with survival and response of patients to co-trimoxazole or other drugs. FINDINGS For patients initially given co-trimoxazole, nine (14%) of 66 with DHPS mutant died, compared with nine (25%) of 36 with wild type (risk ratio50.55 [95% CI=0.24-1.25]; p=0.15). Ten (15%) of 66 patients with a DHPS mutant did not respond to treatment, compared with 13 (36%) of 36 patients with the wild type (0.42 [0.20-0.86]; p=0.02). For patients aged 40 years or older, four (14%) of 29 with the mutant and nine (56%) of 16 with the wild type died (0.25 [0.09-0.67]; p=0.005). INTERPRETATION These results, by contrast with those of previous studies, suggest that patients with wild-type P carinii do not have a better outcome than patients with the mutant when given co-trimoxazole. Our results suggest that presence of a DHPS mutation should be only one of several criteria guiding the choice of initial drug treatment of P carinii pneumonia in patients with HIV-1 infection.
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Affiliation(s)
- T R Navin
- Division of Parasitic Diseases, National Center for Infectious, Diseases, Centers for Disease Control and Prevention, United States Public Health Service, Department of Health and Human Services, Atlanta, GA, USA
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113
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MAYAUD C, CADRANEL J. AIDS and the lung in a changing world. Thorax 2001. [DOI: 10.1136/thx.56.6.423] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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114
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Ma L, Kovacs JA. Rapid detection of mutations in the human-derived Pneumocystis carinii dihydropteroate synthase gene associated with sulfa resistance. Antimicrob Agents Chemother 2001; 45:776-80. [PMID: 11181359 PMCID: PMC90372 DOI: 10.1128/aac.45.3.776-780.2001] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Recent studies have shown that point mutations in the dihydropteroate synthase (DHPS) gene of human-derived Pneumocystis carinii are related to exposure to sulfa drugs and possibly represent the emergence of sulfa resistance. We developed a simple single-strand conformation polymorphism (SSCP) method to permit rapid detection of these mutations. With plasmid constructs, SSCP was able to detect as little as 10% of a minority population. The SSCP assay was compared to direct sequencing for typing the DHPS gene by examining 37 clinical isolates with known DHPS sequences and 41 clinical isolates with unknown DHPS sequences. The typing results were consistent between these two methods for all isolates except 11 in which mutations were detected by SSCP but not by direct sequencing. Sequencing of individual clones after subcloning confirmed the presence of mutations in a minority population as determined by SSCP. SSCP is a very simple and sensitive method for rapid identification of P. camii DHPS mutations.
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Affiliation(s)
- L Ma
- Critical Care Medicine Department, Warren Grant Magnuson Clinical Center, National Institutes of Health, Bethesda, Maryland 20892, USA
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115
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Ye D, Lee CH, Queener SF. Differential splicing of Pneumocystis carinii f. sp. carinii inosine 5'-monophosphate dehydrogenase pre-mRNA. Gene 2001; 263:151-8. [PMID: 11223253 DOI: 10.1016/s0378-1119(00)00577-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Inosine 5'-monophosphate dehydrogenase (IMPDH) is a rate-limiting enzyme in guanine nucleotide metabolism that has drawn attention as a drug target in several organisms. Pneumocystis carinii f. sp. carinii IMPDH mRNA (GeneBank Accession No: U42442) previously identified from cultured organisms yielded a predicted amino acid sequence about 70 amino acids shorter at the amino terminus than IMPDH from other species. Recent research has shown that the amino terminal region is important for enzyme activity, suggesting that the previous putative P. carinii IMPDH might not represent full length, functional enzyme. To test this hypothesis, RT-PCR was performed with total RNA isolated from P. carinii f. sp. carinii. Three IMPDH splicing variants were found and splicing preference was observed: P. carinii isolated from infected rat lung contained primarily splicing variant one (introns two and four deleted), but organisms from spinner flask culture contained primarily splicing variant three (all four introns deleted). Importantly, splicing variant one (GeneBank Accession No: AF196975) contained an open reading frame for 529 amino acids, a size comparable to that of other eukaryotic IMPDH forms. The other variants contained the same open reading frame (454 amino acids) previously reported. Sequence analysis and complementation studies suggest variant one represents the full length, catalytically active form of P. carinii IMPDH. The differential splicing of the enzyme may reflect a mechanism by which the organism regulates the expression of IMPDH in response to environmental stresses.
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Affiliation(s)
- D Ye
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, 635 Barnhill Drive, Indianapolis, IN 46202-5120, USA
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116
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Ma L, Kovacs JA. Expression and characterization of recombinant human-derived Pneumocystis carinii dihydrofolate reductase. Antimicrob Agents Chemother 2000; 44:3092-6. [PMID: 11036028 PMCID: PMC101608 DOI: 10.1128/aac.44.11.3092-3096.2000] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Dihydrofolate reductase (DHFR) is the target of trimethoprim (TMP), which has been widely used in combination with sulfa drugs for treatment and prophylaxis of Pneumocystis carinii pneumonia. While the rat-derived P. carinii DHFR has been well characterized, kinetic studies of human-derived P. carinii DHFR, which differs from rat-derived P. carinii DHFR by 38% in amino acid sequence, have not been reported to date. Here we report on the expression and kinetic characterization of the recombinant human-derived P. carinii DHFR. The 618-bp coding sequence of the human-derived P. carinii DHFR gene was expressed in Escherichia coli. As determined by sodium dodecyl sulfate-polyacrylamide gel eletrophoresis, the purified enzyme had a molecular mass of 25 kDa, consistent with that predicted from the DNA sequence. Kinetic analysis showed that the K(m) values for dihydrofolate and NADPH were 2.7 +/- 0.3 and 14.0 +/- 4.3 microM, respectively, which are similar to those reported for rat-derived P. carinii DHFR. Inhibition studies revealed that both TMP and pyrimethamine were poor inhibitors of human-derived P. carinii DHFR, with K(i) values of 0.28 +/- 0.08 and 0.065 +/- 0.005 microM, respectively, while trimetrexate and methotrexate were potent inhibitors, with K(i) values of 0.23 +/- 0.03 and 0.016 +/- 0.004 nM, respectively. The availability of purified recombinant enzyme in large quantities should facilitate the identification of antifolate inhibitors with greater potency and higher selectivity for human-derived P. carinii DHFR.
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Affiliation(s)
- L Ma
- Critical Care Medicine Department, Warren Grant Magnuson Clinical Center, National Institutes of Health, Bethesda, Maryland, USA
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117
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Kovacs JA, Masur H. Prophylaxis against opportunistic infections in patients with human immunodeficiency virus infection. N Engl J Med 2000; 342:1416-29. [PMID: 10805828 DOI: 10.1056/nejm200005113421907] [Citation(s) in RCA: 172] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Affiliation(s)
- J A Kovacs
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, MD 20892-1662, USA
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118
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Beard CB, Carter JL, Keely SP, Huang L, Pieniazek NJ, Moura IN, Roberts JM, Hightower AW, Bens MS, Freeman AR, Lee S, Stringer JR, Duchin JS, del Rio C, Rimland D, Baughman RP, Levy DA, Dietz VJ, Simon P, Navin TR. Genetic variation in Pneumocystis carinii isolates from different geographic regions: implications for transmission. Emerg Infect Dis 2000; 6:265-72. [PMID: 10827116 PMCID: PMC2640877 DOI: 10.3201/eid0603.000306] [Citation(s) in RCA: 189] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
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.
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Affiliation(s)
- C B Beard
- Centers for Disease Control and Prevention, Atlanta, Georgia 30341-3724, USA.
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