Journal of Microbiology

Alteration of chromosomal structure within β-Tubulin and flagellar calmodulin genes during differentiation of Naegleria gruberi Amebae into Flagellates: Bok, Jin Woong , Lee, Joo Hun; J. Microbiol. 1995;33(3):222-227.

Abstract: We have examined DNase I sensitivity of β-tubulin and flagellar calmodulin genes which are transiently and coordinately activated differentiation of Naegleria gruberi amebae into flagellates. The DNase I sensitivity of β-tubulin and flagellar calmodulin genes changed in parallel with the changes in transcriptional activity of the respective genes during differentiation. The two genes were resistant to DNase I inamebae stage when transcription of the two genes was inactive. Forty minutes after initiation of differentiation, when the two genes were most actively being transcribed, the two genes showed the highest sensitsivity to DNase I. One hundred and twenty minutes after initiation, the differentiation was completed and transcriptional activity of the two genes decreased to a low level. At this stage, the two genes were resistant to DNase I treatment like the ones at the ameba stage. This change in the DNase I sensitivity of the two genes was not observed when transcription of the two genes was blocked by adding cycloheximide at the beginning of differentiation.

Cloning and sequence determination of α-tubulin, β-tubline and Flagellar Calmodulin cDNAs of Naegleria gruberi: Choi, Youn Jeong , Park, Hye Lee , Lee, Joo Hun; J. Microbiol. 1995;33(1):40-45.

Abstract: Five cDNAs encoding two α-tubulins(α13 and α15), two β-tubulins(β5 and β5), and one flagellar calmodulin (Cal-1) were cloned from naegleria gruberi NB-1 and their nt sequences were determined. The α13(EMBL number X81049) and β1(EMBL number X81050) contained a complete open reading frame for α-tubulin and β-tubulin, respectively. The other three clones (α15, β5 and Cal-1) had a part of coding region and a 3’ untranslated region of the respective genes. The α13, β1 and Cal-1 had no homologous sequences in the coding regions and in the 3’ untranslated sequences. However, the α13 and β1 shared an eight nucleotide (AATACAAA) sequence in front of the respective initiation codons. The AATACAAA sequence was also found in N. gruberi strain NEG α-tubulin cDNA clone(αpT1) at the same position. Comparison of the α13 to the αpT1 revealed another stretch of identical sequence, which is 30 nts long, in the 5’ untranlated region.

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