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Maf1-mediated repression of RNA polymerase III transcription inhibits tRNA degradation via RTD pathway

Turowski, TW and Karkusiewicz, Iwona and Kowal, J and Boguta, Magdalena (2012) Maf1-mediated repression of RNA polymerase III transcription inhibits tRNA degradation via RTD pathway. RNA, 18 (10). ISSN 1355-8382 (In Press)


Official URL: http://rnajournal.cshlp.org/


tRNA precursors, which are transcribed by RNA polymerase III, undergo end-maturation, splicing and base modifications. Hypomodified tRNAs, such as tRNAVal(AAC), lacking 7-methylguanosine and 5-methylcytidine modifications, are subject to degradation by a rapid tRNA decay pathway. Here we searched for genes which, when overexpressed, restored stability of tRNAVal(AAC) molecules in a modification–deficient trm4Δtrm8Δ mutant. We identified TEF1 and VAS1, encoding elongation factor eEF1A and valyl-tRNA synthetase respectively, which likely protect hypomodified tRNAVal(AAC) by direct interactions. We also identified MAF1 whose product is a general negative regulator of RNA polymerase III. Expression of an Maf1-7A mutant that constitutively repressed RNA polymerase III transcription resulted in increased stability of hypomodified tRNAVal(AAC). Strikingly, inhibition of tRNA transcription in a Maf1-independent manner, either by point mutation in RNA polymerase III subunit Rpc128 or decreased expression of Rpc17 subunit, also suppressed the turnover of the hypomodified tRNAVal(AAC). These results support a model where inhibition of tRNA transcription leads to stabilization of hypomodified tRNAVal(AAC) due to more efficient protection by tRNA-interacting proteins.

Item Type:Article
Subjects:Q Science > QD Chemistry
Q Science > QR Microbiology
Divisions:Department of Genetics
ID Code:351
Deposited By: profesor Magdalena Boguta
Deposited On:01 Oct 2012 11:09
Last Modified:17 Oct 2014 13:48

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