UspA2, a major OMP of M. catarrhalis, binds vitronectin, a component of both plasma and the extracellular matrix, and confers serum resistance of M. catarrhalis [14]. Furthermore, the UspA2 is able to bind human C3 and C4bp protecting

M. catarrhalis from complement-mediated killing [15, 16]. The surface protein Hag/MID that acts as an adhesin and hemagglutinin, exhibits unique immunoglobulin (Ig) D-binding properties and binds to both soluble and Selleckchem Barasertib membrane-bound IgD on B cells [17–19]. Our previous study demonstrated that exposure of M. catarrhalis to 26°C down-regulates hag mRNA expression [9], indicating a possible involvement of Hag in the cold shock response. In the present study we investigated the effect of a 26°C cold shock on the expression of genes involved in iron acquisition, serum resistance and immune evasion. Cold shock induced the expression of genes involved in transferrin/lactoferrin acquisition and enhanced binding of these proteins on the surface of M. catarrhalis. Exposure of M. catarrhalis to 26°C upregulated the expression of UspA2, a major OMP involved in serum resistance, leading to the improved vitronectin binding. In contrast, cold

shock decreased the expression of Hag, a major adhesin mediating B cell response, and reduced IgD-binding on the surface of M. catarrhalis. Methods Bacterial strains and culture conditions M. catarrhalis strain O35E, its Ro 61-8048 cost isogenic tbpB (O35E.tbpB), uspA1 (O35E.uspA1), uspA2 (O35E.uspA2), hag (O35E.hag) and lpxA (O35E.lpxA) mutants, and clinical isolates 300 and 415 have see more been described elsewhere [9, 20, 21]. Bacteria were cultured at 37°C and 200 rpm in brain heart infusion (BHI) broth (Difco) or on BHI agar plates in an atmosphere containing 5% CO2. Cold shock experiments were performed as described [9]. Bacteria were grown overnight at 37°C, resuspended in fresh medium and grown to mid-logarithmic phase (optical density at 600 nm [OD600] of 0.3). Subsequently, bacteria Protein kinase N1 were exposed to 26°C or 37°C, respectively, for 3 hours (unless otherwise

stated). The growth rates of M. catarrhalis under iron depletion conditions were evaluated by culturing the bacteria in BHI containing 30 μM desferioxamine (Desferal; Novartis). RNA methods RNA for mRNA expression analysis was isolated and used for complementary DNA (cDNA) synthesis as described elsewhere [9]. Generated cDNA was amplified by semi-quantitative polymerase chain reaction (PCR) using primers for lbpB (5′-GCAAGGCGGTAGGGCAGAT-3′, 5′-CCTGCTTTTTCGGCGGTGTC-3′), lbpA (5′-AACAACGCATTCACAGCACCGATT-3′, 5′-GATACCAAGACGAGCGGTGATG-3′), tbpB (5′-CAAGCAGGCCGGTGGTATGG-3′, 5′-GGTAAATGGGGTGAATGTGGTTGC-3′), tbpA (5′-AAGGCGGAGGCAACAGATAAGACA-3′, 5′-AGAGCCAGATAATGCCCCAGAGC-3′) and 16S ribosomal RNA [rRNA] (5′-AAGGTTTGATC(AC)TGG(CT)TCAG-3′, 5′-CTTTACGCCCA(AG)T(AG)A(AT)TCCG-3′).