An exonuclease requiring an intact helical stem for specificity produces the 3' end of Acanthamoeba castellanii 5 S RNA.
A nuclear extract from Acanthamoeba castellanii which contains all of the components necessary for specific transcription of a 5 S RNA gene was separated into fractions required for specific transcription initiation and an additional fraction needed in the reconstituted system to produce the 3' end characteristic of mature 5 S RNA. The latter fraction contained a novel processing activity characterized by an exonuclease specific for highly structured RNAs, including 5 S RNA. An intact helical stem formed between the 5' and 3' ends of the 5 S RNA precursor determines the 3' nucleotide. In addition, the presence of ATP is required for specific processing. However, the possibility has not been ruled out that ATP inhibits a nonspecific ribonuclease in the extract since processing proceeds into the helical stem in its absence.
Imboden
M A
MA
Department of Biochemistry, Colorado State University, Fort Collins 80523.
Matthews
J L
JL
Lofquist
A K
AK
Paule
M R
MR
D000048:Acanthamoeba / Q000201:enzymology* / Q000235:genetics; D000227:Adenine Nucleotides / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001483:Base Sequence; D002467:Cell Nucleus / Q000378:metabolism; D005092:Exonucleases / Q000378:metabolism*; D007700:Kinetics; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009690:Nucleic Acid Conformation; D009843:Oligoribonucleotides; D015347:RNA Probes; D012341:RNA, Ribosomal, 5S / Q000096:biosynthesis / Q000235:genetics*; D015183:Restriction Mapping; D012260:Ribonucleases / Q000378:metabolism*; D014158:Transcription, Genetic
D000227:Adenine Nucleotides; D009843:Oligoribonucleotides; D015347:RNA Probes; D012341:RNA, Ribosomal, 5S; D000255:Adenosine Triphosphate; D005092:Exonucleases; D012260:Ribonucleases