Dataset Information

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.

ABSTRACT: 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.

SUBMITTER: Smulian AG

PROVIDER: S-EPMC173824 | biostudies-other | 1996 Mar

REPOSITORIES: biostudies-other

ACCESS DATA

Publications

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.

Smulian A G AG Ryan M M Staben C C Cushion M M

Infection and immunity 19960301 3

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. ca ...[more]

PMID: 8641768

Similar Datasets

Project description:Fungi in the genus Pneumocystis live in the lungs of mammals, where they can cause a fatal pneumonia (PCP [Pneumocystis pneumonia]) in hosts with compromised immune systems. The absence of a continuous in vitro culture system for any species of Pneumocystis has led to limited understanding of these fungi, especially for the discovery of new therapies. We recently reported that Pneumocystis carinii, Pneumocystis murina, and most significantly, Pneumocystis jirovecii lack both enzymes necessary for myo-inositol biosynthesis but contain genes with homologies to fungal myo-inositol transporters. Since myo-inositol is essential for eukaryotic viability, the primary transporter, ITR1, was functionally and structurally characterized in P. carinii The predicted structure of P. carinii ITR1 (PcITR1) contained 12 transmembrane alpha-helices with intracellular C and N termini, consistent with other inositol transporters. The apparent Km was 0.94 ± 0.08 (mean ± standard deviation), suggesting that myo-inositol transport in P. carinii is likely through a low-affinity, highly selective transport system, as no other sugars or inositol stereoisomers were significant competitive inhibitors. Glucose transport was shown to use a different transport system. The myo-inositol transport was distinct from mammalian transporters, as it was not sodium dependent and was cytochalasin B resistant. Inositol transport in these fungi offers an attractive new drug target because of the reliance of the fungi on its transport, clear differences between the mammalian and fungal transporters, and the ability of the host to both synthesize and transport this critical nutrient, predicting low toxicity of potential inhibitors to the fungal transporter. myo-Inositol is a sugarlike nutrient that is essential for life in most organisms. Humans and microbes alike can obtain it by making it, which involves only 2 enzymes, by taking it from the environment by a transport process, or by recycling it from other cellular constituents. Inspection of the genomes of the pathogenic fungi of the genus Pneumocystis showed that these pneumonia-causing parasites could not make myo-inositol, as they lacked the 2 enzymes. Instead, we found evidence of inositol transporters, which would import the sugar from the lungs where the fungi reside. In the present report, we characterized the transport of myo-inositol in the fungus and found that the transporter was highly selective for myo-inositol and did not transport any other molecules. The transport was distinct from that in mammalian cells, and since mammals can both make and transport myo-inositol, while Pneumocystis fungi must transport it, this process offers a potential new drug target.

Dataset Information

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.

Publications

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.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets