Comparative genome-wide identification of transcriptional start sites in two environmentally relevant cyanobacteria reveals unexpected diversity in the transcriptome architecture
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ABSTRACT: Prochlorococcus is a genus of abundant and ecologically important marine cyanobacteria. Here, we present the comprehensive comparison of the structure and composition of the transcriptomes of two closely related Prochlorococcus strains, which, despite their similarities, have adapted their gene pool to specific environmental constraints. We used large-scale strand-specific cDNA sequencing, microarray RNA profiling and computational analyses to characterize the transcriptomes of Prochlorococcus sp. MED4 and Prochlorococcus sp. MIT9313, representatives of the two major ecotypes adapted to high and low light conditions, respectively. We present genome-wide maps of transcriptional start sites (TSS) for both organisms. Our data suggest antisense transcription for three quarters of all genes. A direct comparison revealed very little conservation in the use of TSS and the nature of non-coding transcripts between both strains. We conclude that the major transcriptional output from these highly streamlined genomes consists of antisense RNA and that a hitherto unrecognized high degree of variability exists in the transcriptional architecture of these rapidly evolving prokaryotes. Furthermore, we detected extremely short 5’ untranslated regions with a median length of only 27 nt and 29 nt for MED4 and MIT9313, respectively, and noticed the absence of the Shine-Dalgarno motif, which is suggestive of alternative mechanisms for the initiation of translation. For 8 % of all protein-coding genes, the median length to the initiator codon is 10 nt or shorter, suggesting that leaderless translation and ribosomal protein S1-dependent translation constitute the primary avenues for protein synthesis in Prochlorococcus.
ORGANISM(S): Prochlorococcus marinus str. MIT 9313 Tiamatvirus PSSP7 Prochlorococcus marinus subsp. pastoris str. CCMP1986 Prochlorococcus phage P-SSM4
PROVIDER: GSE53065 | GEO | 2013/12/07
SECONDARY ACCESSION(S): PRJNA230785
REPOSITORIES: GEO
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