S. Moshitchmoshkovitch et al., REGULATION OF EXPRESSION OF RIBOSOMAL-PROTEIN L-21 GENES OF ENTAMOEBA-HISTOLYTICA AND ENTAMOEBA-DISPAR IS AT THE POSTTRANSCRIPTIONAL LEVEL, Molecular microbiology, 27(4), 1998, pp. 677-685
Two genes, EhgLE3 and Ehg34, encoding the ribosomal protein L21 (rp-L2
1) were identified and characterized from Entamoeba histolytica, Their
coding regions are highly conserved, but their flanking regions diffe
r significantly. Analogous genes (EdgLE3 and Edg34) were characterized
in E. dispar. The two rp-L21 copies are transcribed at similar levels
in the two parasites. However, their relative binding to the polyribo
somal complex during active translation is different. In E. histolytic
a, binding of EhgLE3 transcripts to the polyribosomes is significantly
higher in comparison with that of Ehg34 transcripts, whereas in E, di
spar the binding pattern is inverse. The importance of each of the rp-
L21 flanking regions to gene translation was investigated by construct
ing hybrid plasmids containing the CAT reporter gene flanked by rp-L21
flanking regions. The plasmids were stably transfected into E. histol
ytica and E. dispar, and CAT mRNA and enzymatic activity levels were d
etermined, All plasmids promoted transcription of CAT. Yet, in E. hist
olytica, high levels of CAT activity were observed only when gLE3 upst
ream regions flanked CAT. In contrast, in E. dispar, high levels of CA
T activity were observed when g34 upstream regions flanked CAT. The do
wnstream regions showed no significant effect on CAT translation.