R. Petter et al., CHARACTERIZATION OF 2 DISTINCT GENE TRANSCRIPTS FOR RIBOSOMAL-PROTEIN-L21 FROM PATHOGENIC AND NONPATHOGENIC STRAINS OF ENTAMOEBA-HISTOLYTICA, Gene, 150(1), 1994, pp. 181-186
A second gene (rp-L21) copy clone g34, coding for ribosomal (r-) prote
in L21, was isolated from the pathogenic (P) strain HM-1:IMSS c16 of t
he intestinal parasite Entamoeba histolytica (Eh). The gene was compar
ed to the previously isolated copy, gLE3 [Petter et al., Mel. Biochem.
Parasitol. 56(1992) 329-334], with respect to its primary structure,
mRNA levels and binding to the r-complex during translation. Unlike th
e gLE3 gene copy [Petter et al., Mel. Biochem. Parasitol. 56(1992) 329
-334], g34 was found not to be physically connected to an actin gene c
opy. Homologous copies of the two rp-L21 genes were also characterized
from the nonpathogenic (NP) strain SAW1734R clAR, as well as from its
P derivative. Sequence comparison of the coding regions of the two rp
-L21 revealed almost full identity. Significant differences were found
, however, within their 3' and 5' flanking regions. Using the 3' rapid
amplification of cDNA ends (3' RACE) method [Frohman et al., Proc. Na
tl. Acad. Sci. USA 85 (1985) 8998-9002], as well as Northern and slot
blot hybridizations, it was demonstrated that both rp-L21 mRNAs are fo
und in similar amounts. However, as was shown by differential hybridiz
ation, the relative binding of each transcript to the r-complex varied
somewhat between P and NP strains. This finding suggests that the con
trol of expression of rp-L21 in Eh may involve regulation at the post-
transcriptional level.