Characterization of the Moraxella catarrhalis uspA1 uspA2 genes and their encoded products

The uspA1 and uspA2 genes of M. catarrhalis O35E encode two different surfa ce-exposed proteins which were previously shown to share a 140-amino-acid r egion with 93% identity (C. Aebi, I. Maciver, J. L, Latimer, L. D. Cope, M. K. Stevens, S. E. Thomas, G. H. McCracken, Jr., and E. J. Hansen, Infect. Immun, 65:4367-4377, 1997), The N-terminal amino acid sequences of the matu re forms of both UspA1 and UspA2 from strain O35E were determined after enz ymatic treatment to remove the N-terminal pyroglutamyl residue that had blo cked Edman degradation. Mass spectrometric analysis indicated that the mole cular mass of UspA1 from nt catarrhalis O35E was 83,500 +/- 116 Da, Nucleot ide sequence analysis of the uspA1 and uspA2 gents from three other M catar rhalis strains (TTA24, ATCC 25238, and V1171) revealed that the encoded pro tein products were very similar to those from strain O35E, Western blot ana lysis was used to confirm that each of these three strains of M. catarrhali s expressed both UspA1 and UspA2 proteins. Several different and repetitive amino acid motifs were present in both UspA1 and UspA2 from these four str ains, and some of these were predicted to form coiled coils. Linear DNA tem plates were used in an in vitro transcription-translation system to determi ne the sizes of the monomeric forms of the UspA1 and UspA2 proteins from st rains O35E and TTA24.