This message contains My NCBI what's new results from the National Center for Biotechnology Information (NCBI) at the U.S. National Library of Medicine (NLM).
Do not reply directly to this message.
Sender's message:
Sent on Friday, 2009 Mar 13Search kinetoplastids OR kinetoplastid OR Kinetoplastida OR "trypanosoma brucei" OR leishmania OR brucei OR leishmaniasis OR "African trypanosomiasis"
Click here to view complete results in PubMed. (Results may change over time.)
To unsubscribe from these e-mail updates click here.
| PubMed Results |
- 1: Proc Natl Acad Sci U S A. 2009 Mar 11. [Epub ahead of print]
-
The canonical pathway for selenocysteine insertion is dispensable in Trypanosomes.
Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland;
The micronutrient selenium is found in proteins as selenocysteine (Sec), the 21st amino acid cotranslationally inserted in response to a UGA codon. In vitro studies in archaea and mouse showed that Sec-tRNA(Sec) formation is a 3-step process starting with serylation of tRNA(Sec) by seryl-tRNA synthetase (SerRS), phosphorylation of serine to form phosphoserine (Sep)-tRNA(Sec) by phosphoseryl-tRNA(Sec) kinase (PSTK), and conversion to Sec-tRNA(Sec) by Sep-tRNA:Sec-tRNA synthase (SepSecS). However, a complete study of eukaryotic selenoprotein synthesis has been lacking. Here, we present an analysis of Sec-tRNA(Sec) formation in the parasitic protozoon Trypanosoma brucei in vivo. Null mutants of either PSTK or SepSecS abolished selenoprotein synthesis, demonstrating the essentiality of both enzymes for Sec-tRNA(Sec) formation. Growth of the 2 knockout strains was not impaired; thus, unlike mammals, trypanosomes do not require selenoproteins for viability. Analysis of conditional RNAi strains showed that SerRS, selenophosphate synthase, and the Sec-specific elongation factor, EFSec, are also essential for selenoprotein synthesis. These results with T. brucei imply that eukaryotes have a single pathway of Sec-tRNA(Sec) synthesis that requires Sep-tRNA(Sec) as an intermediate.
PMID: 19279205 [PubMed - as supplied by publisher]
-
Related Articles
- RNA-dependent conversion of phosphoserine forms selenocysteine in eukaryotes and archaea. [Proc Natl Acad Sci U S A. 2006]
- New developments in selenium biochemistry: selenocysteine biosynthesis in eukaryotes and archaea. [Biol Trace Elem Res. 2007]
- Divergence of selenocysteine tRNA recognition by archaeal and eukaryotic O-phosphoseryl-tRNASec kinase. [Nucleic Acids Res. 2008]
- Review[Biochemical selenocysteine synthesis and the phylogenic study] [Yakugaku Zasshi. 2008]
- ReviewMechanism and regulation of selenoprotein synthesis. [Annu Rev Nutr. 2003]
- 2: BMC Cell Biol. 2008 Dec 17;9:68.
-
Silencing cytokeratin 18 gene inhibits intracellular replication of Trypanosoma cruzi in HeLa cells but not binding and invasion of trypanosomes.
Centro Interdisciplinar de Terapia Gênica (CINTERGEN), Universidade Federal de São Paulo-Escola Paulista de Medicina, Rua Mirassol, 207, São Paulo-SP 04044-010, Brazil. carla_claser@immunol.a-star.edu.sg
BACKGROUND: As an obligatory intracellular parasite, Trypanosoma cruzi, the etiological agent of Chagas' disease, must invade and multiply within mammalian cells. Cytokeratin 18 (CK18) is among the host molecules that have been suggested as a mediator of important events during T. cruzi-host cell interaction. Based on that possibility, we addressed whether RNA interference (RNAi)-mediated down regulation of the CK18 gene could interfere with the parasite life cycle in vitro. HeLa cells transiently transfected with CK18-RNAi had negligible levels of CK18 transcripts, and significantly reduced levels of CK18 protein expression as determined by immunoblotting or immunofluorescence. RESULTS: CK18 negative or positive HeLa cells were invaded equally as well by trypomastigotes of different T. cruzi strains. Also, in CK18 negative or positive cells, parasites recruited host cells lysosomes and escaped from the parasitophorous vacuole equally as well. After that, the growth of amastigotes of the Y or CL-Brener strains, was drastically arrested in CK18 RNAi-treated cells. After 48 hours, the number of amastigotes was several times lower in CK18 RNAi-treated cells when compared to control cells. Simultaneous staining of parasites and CK18 showed that in HeLa cells infected with the Y strain both co-localize. Although the amastigote surface protein-2 contains the domain VTVXNVFLYNR previously described to bind to CK18, in several attempts, we failed to detect binding of a recombinant protein to CK-18. CONCLUSION: The study demonstrates that silencing CK18 by transient RNAi, inhibits intracellular multiplication of the Y and CL strain of T. cruzi in HeLa cells, but not trypanosome binding and invasion.
PMID: 19087356 [PubMed - indexed for MEDLINE]
PMCID: PMC2636781
-
Related Articles
- A conserved domain of the gp85/trans-sialidase family activates host cell extracellular signal-regulated kinase and facilitates Trypanosoma cruzi infection. [Exp Cell Res. 2007]
- Cell invasion by Trypanosoma cruzi amastigotes of distinct infectivities: studies on signaling pathways. [Parasitol Res. 2006]
- Interaction with host factors exacerbates Trypanosoma cruzi cell invasion capacity upon oral infection. [Int J Parasitol. 2007]
- ReviewMammalian cell invasion and intracellular trafficking by Trypanosoma cruzi infective forms. [An Acad Bras Cienc. 2005]
- ReviewTrypanosoma cruzi infection by oral route: how the interplay between parasite and host components modulates infectivity. [Parasitol Int. 2008]
No comments:
Post a Comment