title: Evidence for translational control of beta-tubulin synthesis during differentiation of Leishmania donovani.
abstract: Tubulin biosynthesis was rapidly induced during transformation of the mammalian (amastigote) stage of the kinetoplastid parasite Leishmania donovani to flagellated promastigotes. However, transcription of beta-tubulin genes occurred constitutively, as judged by nascent RNA synthesis in isolated nuclei and Northern blotting of steady-state mRNA. Two mRNA species of 2.2 and 2.4 kb were shared by the two cell-types, while a third 2.6 kb species, constituting about 20% of the total, was present in large amounts in promastigotes. RNase protection experiments demonstrated sequence microheterogeneity in the 5'-untranslated region, the pattern of which was identical in promastigotes and amastigotes. By primer extension assays, heterogeneity in the 5'-terminal cap structure of amastigote beta-tubulin mRNA and differential pausing of reverse transcriptase within the mini-exon leader region were detected. These differences correlated with enhanced translational efficiency of tubulin mRNA from promastigotes in a rabbit reticulocyte lysate system. The results indicate that translational control plays a major role in tubulin induction during L. donovani differentiation.
authors.affiliation: Genetic Engineering Laboratory, Indian Institute of Chemical Biology, Calcutta.
authors.forename: M
authors.initials: M
authors.lastname: Bhaumik
authors.forename: S
authors.initials: S
authors.lastname: Das
authors.forename: S
authors.initials: S
authors.lastname: Adhya
mesh_terms: D000818:Animals; D015152:Blotting, Northern; D007893:Leishmania donovani / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D014176:Protein Biosynthesis; D015800:Protozoan Proteins / Q000096:biosynthesis; D012333:RNA, Messenger / Q000737:chemistry*; D016053:RNA, Protozoan / Q000737:chemistry; D013154:Spleen / Q000469:parasitology; D014158:Transcription, Genetic; D014404:Tubulin / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D015800:Protozoan Proteins; D012333:RNA, Messenger; D016053:RNA, Protozoan; D014404:Tubulin