Characterization of a cDNA clone from the haemoparasite Babesia bovis encoding a protein containing an "HMG-Box".

The complete nucleotide sequence of a Babesia bovis cDNA clone encoding a protein containing an HMG-Box has been determined. The predicted protein of 97 amino acids has a molecular weight of 11,116. It exhibits approximately 45% overall amino acid identity with the Saccharomyces cerevisiae non-histone protein 6A (NHP6A) and approximately 57% identity in the HMG-Box. The B. bovis protein has been designated NHP1. Like HNP6A, and unlike most other HMG1 homologues, NHP1 does not have a basic or an acidic carboxy-terminal domain. The amino acid sequence of HNP1 is much less similar to HMG1 homologues of another protozoan, Tetrahymena thermophila, than to the HMG1 homologues identified in S. cerevisiae, plants and vertebrates. This suggests that the T. thermophila proteins may not be true HMG1 homologues, or that they may be evolving at a much faster rate.