Acidic ribosomal proteins and histone H3 from Leishmania present a high rate of divergence

Abstract

Another additional peculiarity in Leishmania will be discussed about of the amino acid divergence rate of three structural proteins: acidic ribosomal P1 and P2b proteins, and histone H3 by using multiple sequence alignment and dendrograms.These Acidic ribosomal proteins known as P (phospho) proteins are present in the ribosomes belonging to the eubacteria, archaebacteria and eukaryotes. These conserved proteins are placed in the large ribosomal sub-unit forming a highly flexible lateral projection referred as the ribosomal stalk (Wittman 1983, Lake 1985. The stalk is involved in the interaction between the translation factors and the ribosome during protein synthesis (Shimmin et al. 1989).Acidic ribosomal P1 protein in trypanosomatids had not been reported in the Leishmania genus previous to this work. However, the P0 and P2 ribosomal proteins had been characterised in L. infantum (Soto et al. 1995a, b), L. chagasi (Skeiky et al. 1994) and L. donovani (Kunz et al. 1993). Moreover, Trypanosoma cruzi acidic ribosomal protein belong to a gene family found in multiple copies (TcP0, TcP1, TcP2a and TcP2b). The P proteins are important antigens that generate humoral response in leishmaniasis, Chagas disease and systemic lupus erythematosus (Elkon et al. 1986).Despite of presenting histones, the trypanosomatids do not condense their chromatin during mitosis (Solari 1980). Likewise, trypanosomatids histone H3 presents an extremely divergent N-terminal domain (Galanti et al. 1998). Another important peculiarity is that trypanosomatids histone H3 lacks of the amino acids sequence KSTGGKA at the N-terminal end, which is present in the consensus sequence of higher eukaryotes (Wells 1986).Three clones from L. (V.) peruviana (T26-U3) and L. (V.) braziliensis cDNA libraries (T166-U19 and T166-M49) were previously selected by their sero-reactivity with leishmaniasis patients (Montoya 1993). The DNA insert corresponding to each of them was amplified and sub-cloned in pUC18/EcoRI/BAP (Pharmacia) plasmid vector.After sequence analysis, the T26-U3 clone was identified as a L. (V.) peruviana acidic ribosomal protein P1 being referred as LpP1. The clone T166-U19 was recognised as a L. (V.) braziliensis acidic ribosomal protein P2b and referred as LbP2b. Finally, the T166-M49 clone was identified as a L. (V.) braziliensis histone H3 being referred as LbH3.The deduced amino acid sequence of the LpP1 had a divergence of 57.4% in comparison with T. cruzi P1 protein (TcP1). LpP2b showed 17.9% of divergence with the L. donovani ribosomal P2 protein (LdP2) and 41.7% of divergence with their Y Montoya received partial support from a re