Eukaryotic Cell
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Eukaryotic Cell, February 2007, p. 337-345, Vol. 6, No. 2
1535-9778/07/$08.00+0     doi:10.1128/EC.00279-06
Copyright © 2007, American Society for Microbiology. All Rights Reserved.

Small-Subunit rRNA Processome Proteins Are Translationally Regulated during Differentiation of Trypanosoma cruzi{triangledown} ,{dagger}

Sheila Cristina Nardelli,1 Andréa Rodrigues Ávila,1,2 Aline Freund,1 Maria Cristina Motta,3 Lauro Manhães,1 Teresa Cristina Leandro de Jesus,4 Sergio Schenkman,4 Stenio Perdigão Fragoso,1,2 Marco Aurélio Krieger,1,2 Samuel Goldenberg,1,2* and Bruno Dallagiovanna1,2

Instituto de Biologia Molecular do Paraná, Rua Algacyr Munhoz Mader 3775, Curitiba 81350-010, Paraná, Brazil,1 FIOCRUZ, Avenida Brasil 4365, Rio de Janeiro 21040-900, Brazil,2 Instituto de Biofísica Carlos Chagas Filho, UFRJ, Rio de Janeiro 21949-900, Brazil,3 Departamento de Microbiologia, Imunologia e Parasitologia, Rua Botucatu 862-8a, UNIFESP, São Paulo 04023-062, Brazil4

Received 31 August 2006/ Accepted 28 November 2006

We used differential display to select genes differentially expressed during differentiation of epimastigotes into metacyclic trypomastigotes in the protozoan parasite Trypanosoma cruzi. One of the selected clones had a sequence similar to that of the small-subunit (SSU) processome protein Sof1p, which is involved in rRNA processing. The corresponding T. cruzi protein, TcSof1, displayed a nuclear localization and is downregulated during metacyclogenesis. Heterologous RNA interference assays showed that depletion of this protein impaired growth but did not affect progression through the cell cycle, suggesting that ribosome synthesis regulation and the cell cycle are uncoupled in this parasite. Quantitative PCR (qPCR) assays of several SSU processome-specific genes in T. cruzi also showed that most of them were regulated posttranscriptionally. This process involves the accumulation of mRNA in the polysome fraction of metacyclic trypomastigotes, where TcSof1 cannot be detected. Metacyclic trypomastigote polysomes were purified and separated by sucrose gradient sedimentation. Northern blot analysis of the sucrose gradient fractions showed the association of TcSof1 mRNA with polysomes, confirming the qPCR data. The results suggest that the mechanism of regulation involves the blocking of translation elongation and/or termination.

* Corresponding author. Mailing address: Instituto de Biologia Molecular do Paraná, Rua Algacyr Munhoz Mader 3775, Curitiba 81350-010, Paraná, Brazil. Phone: 55-41-316-3260. Fax: 55-41-33163267. E-mail: sgoldenb{at}tecpar.br.

{triangledown} Published ahead of print on 8 December 2006.

{dagger} Supplemental material for this article may be found at http://ec.asm.org/.

Eukaryotic Cell, February 2007, p. 337-345, Vol. 6, No. 2
1535-9778/07/$08.00+0     doi:10.1128/EC.00279-06
Copyright © 2007, American Society for Microbiology. All Rights Reserved.



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Copyright © 2007 by the American Society for Microbiology.