Primary structure ofTrichoderma harzianumribosomal protein L32

Eukaryotic ribosomal proteins (rp) are found to be arranged in relatively large (8 to > 20 member) families of unlinked genes. These families are usually composed by a single intron(s)containing expressed gene, and a number of processed, silent genes (1). One of the most studied of these families, L32, has been shown to be highly conserved among the organisms where it has been identified, i.e, mouse, human and flies (2, 3, 4, 5), but no information was available regarding the lower-eukaryote counterparts. While screening for another gene in a cDNA library from the filamentous fungus Trichoderma harzianum, we isolated a clone whose deduced amino acid sequence showed high homology (around 50% identity) with L32 rp from mouse, human, Drosophila melanogaster and D. subobscura (Figure 1). The cDNA is 562 bp in length and codes for a 137-amino-acid polypeptide. This deduced protein, termed TrpL32, is very rich in basic residues (pI = 12.41) and quite hydrophobic (data not shown) which is in agreement with the information related with the other L32 rp studied so far. From Southern analysis (data not shown) we have seen that this protein is encoded by a single gene or by several very highly homologous ones grouped in a 6 kb Hindm genomic fragment. The expression pattern of the mRNA was investigated by Northern blotting of total mRNA and resulted in a constitutive transcription of the TrpL32 gene. To our knowledge, this is the first gene of L32 rp from a lower eukaryote so far reported and shows a striking similarity with those from the higher ones. EMBL accession no. X71914