RNA-Seq-based analysis of the physiologic cold shock-induced changes in Moraxella catarrhalis gene expression

• Published in: PloS one 2013-07, Vol.8 (7), p.e68298-e68298
• Main Authors: Spaniol, Violeta, Wyder, Stefan, Aebi, Christoph
• Format: Article
• Language: English
• Subjects: Air temperature; Analysis; Bacteria; Biology; Carbohydrate Metabolism - genetics; Causes of; Cold; Cold shock; Cold Temperature; Colonization; Data processing; Development and progression; E coli; Ear diseases; Efflux; Energy Metabolism - genetics; Escherichia coli; Exposure; Gene expression; Gene Expression Regulation, Bacterial; Genes; Genetic aspects; Genetic transformation; Genomes; Genomics; Haemophilus influenzae; Health aspects; Humans; Infections; Infectious diseases; Iron; Lipid Metabolism - genetics; Medicine; Membrane proteins; Metabolism; Moraxella (Branhamella) catarrhalis - genetics; Moraxella (Branhamella) catarrhalis - pathogenicity; Moraxella catarrhalis; Moraxellaceae Infections - microbiology; Nitrogen metabolism; Oligonucleotide Array Sequence Analysis; Outer membrane proteins; Pathogenesis; Pharynx; Phosphates; Physiological aspects; Pili; Polymerase chain reaction; Proteins; Respiratory tract; Respiratory tract diseases; Reverse Transcriptase Polymerase Chain Reaction; Ribonucleic acid; RNA; RNA sequencing; Salmonella; Salmonella Typhimurium; Sequence Analysis, RNA - methods; Temperature; Temperature effects; Transcriptome; Transformation; Trends; Viral infections; Virulence; Virulence (Microbiology); Virulence - genetics
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0068298

Moraxella catarrhalis, a major nasopharyngeal pathogen of the human respiratory tract, is exposed to rapid downshifts of environmental temperature when humans breathe cold air. The prevalence of pharyngeal colonization and respiratory tract infections caused by M. catarrhalis is greatest in winter. We investigated how M. catarrhalis uses the physiologic exposure to cold air to regulate pivotal survival systems that may contribute to M. catarrhalis virulence. In this study we used the RNA-seq techniques to quantitatively catalogue the transcriptome of M. catarrhalis exposed to a 26 °C cold shock or to continuous growth at 37 °C. Validation of RNA-seq data using quantitative RT-PCR analysis demonstrated the RNA-seq results to be highly reliable. We observed that a 26 °C cold shock induces the expression of genes that in other bacteria have been related to virulence a strong induction was observed for genes involved in high affinity phosphate transport and iron acquisition, indicating that M. catarrhalis makes a better use of both phosphate and iron resources after exposure to cold shock. We detected the induction of genes involved in nitrogen metabolism, as well as several outer membrane proteins, including ompA, m35-like porin and multidrug efflux pump (acrAB) indicating that M. catarrhalis remodels its membrane components in response to downshift of temperature. Furthermore, we demonstrate that a 26 °C cold shock enhances the induction of genes encoding the type IV pili that are essential for natural transformation, and increases the genetic competence of M. catarrhalis, which may facilitate the rapid spread and acquisition of novel virulence-associated genes. Cold shock at a physiologically relevant temperature of 26 °C induces in M. catarrhalis a complex of adaptive mechanisms that could convey novel pathogenic functions and may contribute to enhanced colonization and virulence.