Molecular and Cellular Biology, June 2006, p. 4387-4398, Vol. 26, No. 12
0270-7306/06/$08.00+0 doi:10.1128/MCB.00234-06
Copyright © 2006, American Society for Microbiology. All Rights Reserved.
Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Avd. Reina Mercedes 6, 41012 Sevilla, Spain
Received 4 October 2005/ Returned for modification 5 December 2005/ Accepted 21 March 2006
THO is a protein complex that functions in cotranscriptional mRNP formation. Yeast THO1 and SUB2 (Saccharomyces cerevisiae) were identified as multicopy suppressors of the expression defects of the hpr1
mutant of THO. Here we show that multicopy THO1 suppresses the mRNA accumulation and export defects and the hyperrecombination phenotype of THO mutants but not those of sub2
, thp1
, or spt4
. Similarly, Sub2 overexpression suppresses the RNA export defect of hpr1
. Tho1 is a conserved RNA binding nuclear protein that specifically binds to transcribed chromatin in a THO- and RNA-dependent manner and genetically interacts with the shuttling hnRNP Nab2. The ability of Tho1 to suppress hpr1
resides in its C-terminal half, which contains the RNA binding activity and is located after a SAP/SAF (scaffold-associated protein/scaffold-associated factor) domain. Altogether, these results suggest that Tho1 is an hnRNP that, similarly to Sub2, assembles onto the nascent mRNA during transcription and participates in mRNP biogenesis and export. Overexpression of Tho1 or Sub2 may provide alternative ways for mRNP formation and export in the absence of a functional THO complex.
Supplemental material for this article may be found at http://mcb.asm.org/.
This article has been cited by other articles:
Copyright © 2009 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»