title: Caulobacter crescentus CdnL is a non-essential RNA polymerase-binding protein whose depletion impairs normal growth and rRNA transcription.
abstract: CdnL is an essential RNA polymerase (RNAP)-binding activator of rRNA transcription in mycobacteria and myxobacteria but reportedly not in Bacillus. Whether its function and mode of action are conserved in other bacteria thus remains unclear. Because virtually all alphaproteobacteria have a CdnL homolog and none of these have been characterized, we studied the homolog (CdnLCc) of the model alphaproteobacterium Caulobacter crescentus. We show that CdnLCcis not essential for viability but that its absence or depletion causes slow growth and cell filamentation. CdnLCcis degraded in vivo in a manner dependent on its C-terminus, yet excess CdnLCcresulting from its stabilization did not adversely affect growth. We find that CdnLCcinteracts with itself and with the RNAP β subunit, and localizes to at least one rRNA promoter in vivo, whose activity diminishes upon depletion of CdnLCc. Interestingly, cells expressing CdnLCcmutants unable to interact with the RNAP were cold-sensitive, suggesting that CdnLCcinteraction with RNAP is especially required at lower than standard growth temperatures in C. crescentus. Our study indicates that despite limited sequence similarities and regulatory differences compared to its myco/myxobacterial homologs, CdnLCcmay share similar biological functions, since it affects rRNA synthesis, probably by stabilizing open promoter-RNAP complexes.
authors.affiliation: Departamento de Genética y Microbiología, Área de Genética (Unidad Asociada al IQFR-CSIC), Facultad de Biología, Universidad de Murcia, 30100 Murcia, Spain.
authors.forename: Aránzazu
authors.initials: A
authors.lastname: Gallego-García
authors.affiliation: Departamento de Genética y Microbiología, Área de Genética (Unidad Asociada al IQFR-CSIC), Facultad de Biología, Universidad de Murcia, 30100 Murcia, Spain.
authors.forename: Antonio A
authors.initials: AA
authors.lastname: Iniesta
authors.affiliation: Department of Fundamental Microbiology, Faculty of Biology and Medicine, University of Lausanne, Quartier UNIL/Sorge, Lausanne, CH1015, Switzerland.
authors.forename: Diego
authors.initials: D
authors.lastname: González
authors.affiliation: Department of Fundamental Microbiology, Faculty of Biology and Medicine, University of Lausanne, Quartier UNIL/Sorge, Lausanne, CH1015, Switzerland.
authors.forename: Justine
authors.initials: J
authors.lastname: Collier
authors.affiliation: Instituto de Química Física 'Rocasolano', Consejo Superior de Investigaciones Científicas (IQFR-CSIC), Serrano 119, 28006 Madrid, Spain.
authors.forename: S
authors.initials: S
authors.lastname: Padmanabhan
authors.affiliation: Departamento de Genética y Microbiología, Área de Genética (Unidad Asociada al IQFR-CSIC), Facultad de Biología, Universidad de Murcia, 30100 Murcia, Spain.
authors.forename: Montserrat
authors.initials: M
authors.lastname: Elías-Arnanz
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D016935:Caulobacter crescentus / Q000235:genetics / Q000378:metabolism*; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D054730:Protein Interaction Domains and Motifs; D012335:RNA, Ribosomal / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D012335:RNA, Ribosomal; D016601:RNA-Binding Proteins; D012321:DNA-Directed RNA Polymerases