Chromosome walk in Entamoeba histolytica: the gene encoding for ribosomal protein L21 neighbors one of the actin genes.
Actin is one of the most abundant proteins in the motile intestinal protozoan parasite E. histolytica. A number of actin gene copies have been detected. The cDNA and genomic sequences of two of the actin genes have been independently reported (1,2). Almost complete homology was detected between the coding regions of the two genes; however, significant differences were observed in the sequences of their 5' untranslated regions. Using the coding region of actin as the focal point, we performed a chromosome walk to identify the neighboring genes and the intergenic regulatory domains. A genomic library containing large fragments of DNA was screened with the coding and non-coding regions of the actin gene. An insert of 8.5 kb reacted on Northern blots with actin and two additional transcripts. The large (approximately 2.5 kb) transcript has not yet been identified, but the smaller one (600 bp), was shown to encode for the ribosomal protein L21. Both the cDNA and genomic sequences of this gene were determined. The RP-L21 gene was found to be physically connected to the actin gene by a 2.1 kb intergenic stretch. The actin gene on this DNA fragment contained a 5' untranslated region that was identical to the sequence described by Edman et al. The actin gene isolated by Huber et al. was located by PFGE on another chromosomal band that did not contain the RP-L21 gene.
Petter
R
R
MacArthur Center for Molecular Biology of Parasitic Diseases, Weizmann Institute of Science, Rehovot, Israel.
Rozenblatt
S
S
Nuchamowitz
Y
Y
Mirelman
D
D
D000199:Actins / Q000235:genetics*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D016386:Chromosome Walking; D018076:DNA, Complementary / Q000235:genetics; D016521:Electrophoresis, Gel, Pulsed-Field; D004748:Entamoeba histolytica / Q000235:genetics*; D017125:Genes, Protozoan; D008969:Molecular Sequence Data; D005810:Multigene Family; D016133:Polymerase Chain Reaction; D015800:Protozoan Proteins / Q000235:genetics*; D012269:Ribosomal Proteins / Q000235:genetics*; D012689:Sequence Homology, Nucleic Acid
D000199:Actins; D018076:DNA, Complementary; D015800:Protozoan Proteins; D012269:Ribosomal Proteins; C060232:ribosomal protein L21