Genome analysis of Moraxella catarrhalis strain RH4, a Human Respiratory Tract Pathogen.

• Moraxella catarrhalis is an emerging human-restricted respiratory tract pathogen that is a common cause of childhood otitis media and exacerbations of chronic obstructive pulmonary disease in adults. Here, we report the first completely assembled and annotated genome sequence of an isolate of M. catarrhalis: strain RH4, originally isolated from blood of an infected patient. The RH4 genome consists of 1,863,286 nucleotides harboring 1,886 protein-encoding genes. Comparison of the RH4 genome to the ATCC 43617 contigs demonstrated that the gene content of both strains is highly conserved. In silico phylogenetic analyses based on both 16S rRNA and multilocus sequence typing revealed that RH4 belongs to the seroresistant lineage. We were able to identify close to the entire repertoire of known M. catarrhalis virulence factors, and mapped the members of the biosynthetic pathways for lipooligosaccharide, peptidoglycan, and type IV pili. A reconstruction of the central metabolic pathways suggests that RH4 relies on fatty acid and acetate metabolism, as the genes encoding the enzymes required for the glyoxylate pathway, tricarboxylic acid cycle, gluconeogenic pathway, non-oxidative branch of the pentose phosphate pathway, beta-oxidation pathway of fatty acids, and acetate metabolism were present. Moreover, pathways important for survival under in vivo challenging conditions such as iron-acquisition pathways, nitrogen metabolism, and oxidative stress responses were identified. Finally, we showed by microarray expression profiling that approximately 88% of the predicted coding sequences are transcribed under in vitro conditions. Overall, these results provide a foundation for future research into the mechanisms of M. catarrhalis pathogenesis and vaccine development.

Ämnesord

NATURVETENSKAP  -- Biologi -- Mikrobiologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Microbiology (hsv//eng)

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