Isolation of α- and β- tubulin genes of Plasmodium falciparum using a single oligonucleotide probe

An oligonucleotide probe (315) specific for the α- and β-tubulin genes of Plasmodium falciparum was synthesized utilizing codon usage of P. falciparum determined from published gene sequences. By screening genomic and cDNA libraries with the oligonucleotide probe, α- and β-tubulin clones were isolated. Positive clones were identified by partial sequencing and comparing the deduced amino acid sequence with the chicken brain α- and β-tubulin amino acid sequences. The β-tubulin gene was completely sequenced at the genomic level and partially at cDNA level. The deduced polypeptide is 445 amino acids long, shares 88% homology with chicken brain β-tubulin, and contains two introns of 362 and 163 bp long, respectively. α- and β-tubulin genes of P. falciparum are unlinked and dispersed; more than one copy of each gene may be present. Northern blot analysis of total RNA of the blood-stage parasite indicates the presence of three transcripts of α-tubulin (3.3 kb, 2.6 kb, 1.9 kb) and three transcripts of β-tubulin gene (3.6 kb, 2.9 kb, 2.0 kb). The significance of these transcripts is presently unknown.