Cordon-Obras C, Gomez-Liñan C, Torres-Rusillo S, Vidal-Cobo I, Lopez-Farfan D, Barroso-Del Jesus A, Rojas-Barros D, Carrington M, Navarro M. Identification of sequence-specific promoters driving polycistronic transcription initiation by RNA polymerase II in trypanosomes.
Cell Rep 2022;
38:110221. [PMID:
35021094 DOI:
10.1016/j.celrep.2021.110221]
[Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Revised: 10/18/2021] [Accepted: 12/15/2021] [Indexed: 11/20/2022] Open
Abstract
Protein-coding genes in trypanosomes occur in polycistronic transcription units (PTUs). How RNA polymerase II (Pol II) initiates transcription of PTUs has not been resolved; the current model favors chromatin modifications inducing transcription rather than sequence-specific promoters. Here, we uncover core promoters by functional characterization of Pol II peaks identified by chromatin immunoprecipitation sequencing (ChIP-seq). Two distinct promoters are located between divergent PTUs, each driving unidirectional transcription. Detailed analysis identifies a 75-bp promoter that is necessary and sufficient to drive full reporter expression and contains functional motifs. Analysis of further promoters suggests transcription initiation is regulated and promoters are either focused or dispersed. In contrast to the previous model of unregulated and promoter-independent transcription initiation, we find that sequence-specific promoters determine the initiation of Pol II transcription of protein-coding genes PTUs. These findings in Trypanosoma brucei suggest that in addition of chromatin modifications, promoter motifs-based regulation of gene expression is deeply conserved among eukaryotes.
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