Paf1 and Ctr9, core components of the PAF1 complex, maintain low levels of telomeric repeat containing RNA.

Joana Rodrigues,David Lydall

doi:10.1093/nar/gkx1131

Abstract

The conserved PAF1 complex (Cdc73, Paf1, Ctr9, Leo1 and Rtf1, in yeast), binds RNA pol II, and affects levels of many RNAs. Although PAF1 is a complex, there is evidence that different components perform different functions. In yeast, Cdc73, Paf1 and Ctr9 maintain normal telomerase RNA (TLC1) levels and affect telomere length. Here we report a new connection between the PAF1 complex and telomere biology. We show that Paf1 and Ctr9 maintain low telomere repeat containing RNA (TERRA) levels while Cdc73, Leo1 and Rtf1 have lesser effects. Analysis of double mutants shows that Paf1 and Ctr9 can affect TERRA independently of Sir4, Rat1, and Trf4, previously identified regulators of TERRA. The data suggest that Paf1 and Ctr9 maintain low TERRA levels by affecting both transcription and degradation and that short telomeres in cdc73Δ, paf1Δ and ctr9Δ mutants do not induce TERRA. These data establish the PAF1 complex as a new regulator of TERRA, and are consistent with the model in which Paf1 and Ctr9, the core components of the PAF1 complex, affect transcript levels and cell fitness by numerous mechanisms.

Highlights

Cdc73, Paf1, Ctr9, Leo1 and Rtf1 are components of the PAF1 complex in yeast, a transcription elongation factor (TEF), that binds RNA pol II (Figure 1A) and affects RNA levels via a number of routes, transcriptional and posttranscriptional [1,2,3]
Paf1 and Ctr9 are needed for cell fitness and low telomere repeat containing RNA (TERRA) levels
To determine whether TERRA is affected in PAF1 complex mutants, we measured TERRA transcribed from left-arm X telomeres on chromosomes 1 and 15 (TEL01L and TEL15L), where TERRA had previously been measured [26,36]

Summary

INTRODUCTION

Paf, Ctr, Leo and Rtf are components of the PAF1 complex in yeast, a transcription elongation factor (TEF), that binds RNA pol II (Figure 1A) and affects RNA levels via a number of routes, transcriptional and posttranscriptional [1,2,3]. Paf1Δ and ctr9Δ cells are comparatively unfit while cdc73Δ, leo1Δ and rtf1Δ cells are fit, showing that Paf and Ctr are more important for cell function than Cdc, Leo and Rtf1 [12,13]. Cdc73Δ, paf1Δ and ctr9Δ cells have short telomeres due to low levels of TLC1, the RNA component of telomerase, while leo1Δ and rtf1Δ cells have comparatively normal length telomeres and TLC1 levels [13,14].

25 TEL15L TERRA

MATERIALS AND METHODS

RESULTS

TEL15L

10 TEL01L **

DISCUSSION