title: Transcriptome analysis of thermophilic methylotrophic Bacillus methanolicus MGA3 using RNA-sequencing provides detailed insights into its previously uncharted transcriptional landscape.
abstract: BACKGROUND
  Bacillus methanolicus MGA3 is a thermophilic, facultative ribulose monophosphate (RuMP) cycle methylotroph. Together with its ability to produce high yields of amino acids, the relevance of this microorganism as a promising candidate for biotechnological applications is evident. The B. methanolicus MGA3 genome consists of a 3,337,035 nucleotides (nt) circular chromosome, the 19,174 nt plasmid pBM19 and the 68,999 nt plasmid pBM69. 3,218 protein-coding regions were annotated on the chromosome, 22 on pBM19 and 82 on pBM69. In the present study, the RNA-seq approach was used to comprehensively investigate the transcriptome of B. methanolicus MGA3 in order to improve the genome annotation, identify novel transcripts, analyze conserved sequence motifs involved in gene expression and reveal operon structures. For this aim, two different cDNA library preparation methods were applied: one which allows characterization of the whole transcriptome and another which includes enrichment of primary transcript 5'-ends.
  
  
  RESULTS
  Analysis of the primary transcriptome data enabled the detection of 2,167 putative transcription start sites (TSSs) which were categorized into 1,642 TSSs located in the upstream region (5'-UTR) of known protein-coding genes and 525 TSSs of novel antisense, intragenic, or intergenic transcripts. Firstly, 14 wrongly annotated translation start sites (TLSs) were corrected based on primary transcriptome data. Further investigation of the identified 5'-UTRs resulted in the detailed characterization of their length distribution and the detection of 75 hitherto unknown cis-regulatory RNA elements. Moreover, the exact TSSs positions were utilized to define conserved sequence motifs for translation start sites, ribosome binding sites and promoters in B. methanolicus MGA3. Based on the whole transcriptome data set, novel transcripts, operon structures and mRNA abundances were determined. The analysis of the operon structures revealed that almost half of the genes are transcribed monocistronically (940), whereas 1,164 genes are organized in 381 operons. Several of the genes related to methylotrophy had highly abundant transcripts.
  
  
  CONCLUSIONS
  The extensive insights into the transcriptional landscape of B. methanolicus MGA3, gained in this study, represent a valuable foundation for further comparative quantitative transcriptome analyses and possibly also for the development of molecular biology tools which at present are very limited for this organism.
authors.affiliation: Genetics of Prokaryotes, Faculty of Biology & Center for Biotechnology, Bielefeld University, Universitätsstr. 25, 33615, Bielefeld, Germany. mairla@cebitec.uni-bielefeld.de.
authors.forename: Marta
authors.initials: M
authors.lastname: Irla
authors.affiliation: Microbial Genomics and Biotechnology, Center for Biotechnology, Bielefeld University, Universitätstr. 27, 33615, Bielefeld, Germany. armin.neshat@cebitec.uni-bielefeld.de.
authors.forename: Armin
authors.initials: A
authors.lastname: Neshat
authors.affiliation: Department of Molecular Biology, SINTEF Materials and Chemistry, Sem Selands vei 2, 7465, Trondheim, Norway. trygve.brautaset@sintef.no.|Department of Biotechnology, Norwegian University of Science and Technology, Sem Sælands vei 6/8, 7491, Trondheim, Norway. trygve.brautaset@sintef.no.
authors.forename: Trygve
authors.initials: T
authors.lastname: Brautaset
authors.affiliation: Microbial Genomics and Biotechnology, Center for Biotechnology, Bielefeld University, Universitätstr. 27, 33615, Bielefeld, Germany. christian.rueckert@cebitec.uni-bielefeld.de.|Technology Platform Genomics, Center for Biotechnology, Bielefeld University, Universitätsstr. 27, 33615, Bielefeld, Germany. christian.rueckert@cebitec.uni-bielefeld.de.
authors.forename: Christian
authors.initials: C
authors.lastname: Rückert
authors.affiliation: Microbial Genomics and Biotechnology, Center for Biotechnology, Bielefeld University, Universitätstr. 27, 33615, Bielefeld, Germany. joern.kalinowski@cebitec.uni-bielefeld.de.|Technology Platform Genomics, Center for Biotechnology, Bielefeld University, Universitätsstr. 27, 33615, Bielefeld, Germany. joern.kalinowski@cebitec.uni-bielefeld.de.
authors.forename: Jörn
authors.initials: J
authors.lastname: Kalinowski
authors.affiliation: Genetics of Prokaryotes, Faculty of Biology & Center for Biotechnology, Bielefeld University, Universitätsstr. 25, 33615, Bielefeld, Germany. volker.wendisch@uni-bielefeld.de.
authors.forename: Volker F
authors.initials: VF
authors.lastname: Wendisch
mesh_terms: D020121:5' Untranslated Regions; D001407:Bacillus / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics; D016680:Genome, Bacterial; D011401:Promoter Regions, Genetic; D050436:Regulatory Elements, Transcriptional; D012270:Ribosomes / Q000378:metabolism; D017423:Sequence Analysis, RNA; D024363:Transcription Initiation Site; D059467:Transcriptome
chemical_list: D020121:5' Untranslated Regions; D001426:Bacterial Proteins