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First published online 19 August 2008
doi: 10.1242/jcs.031823
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Research Article |
phosphorylation at Thr169
1 Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge CB2 1GA, UK
2 ZMBH, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany
3 Deutsches Krebsforschungszentrum, Im Neuenheimer Feld 580, 69120 Heidelberg, Germany
* Author for correspondence (e-mail: mc115{at}cam.ac.uk)
Accepted 30 June 2008
In trypanosomes there is an almost total reliance on post-transcriptional mechanisms to alter gene expression; here, heat shock was used to investigate the response to an environmental signal. Heat shock rapidly and reversibly induced a decrease in polysome abundance, and the consequent changes in mRNA metabolism were studied. Both heat shock and polysome dissociation were necessary for (1) a reduction in mRNA levels that was more rapid than normal turnover, (2) an increased number of P-body-like granules that contained DHH1, SCD6 and XRNA, (3) the formation of stress granules that remained largely separate from the P-body-like granules and localise to the periphery of the cell and, (4) an increase in the size of a novel focus located at the posterior pole of the cell that contain XRNA, but neither DHH1 nor SCD6. The response differed from mammalian cells in that neither the decrease in polysomes nor stress-granule formation required phosphorylation of eIF2
at the position homologous to that of serine 51 in mammalian eIF2
and in the occurrence of a novel XRNA-focus.
Key words: Heat shock, Trypanosoma brucei, Stress granules, eIF2 alpha, P-bodies
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