Several regions of a tRNA precursor determine the Escherichia coli RNase P cleavage site.
J Mol Biol
; 227(4): 1019-31, 1992 Oct 20.
Article
en En
| MEDLINE
| ID: mdl-1279179
ABSTRACT
The RNase P cleavage reaction was studied as a function of the number of base-pairs in the acceptor-stem and/or T-stem of a natural tRNA precursor, the tRNA(Tyr)Su3 precursor. Our data suggest that the location of the Escherichia coli RNase P cleavage site does not depend merely on the lengths of the acceptor-stem and T-stem as previously suggested. Surprisingly, we find that precursors with only four base-pairs in the acceptor-stem are cleaved by M1 RNA and by holoenzyme. Furthermore, we show that both disruption of base-pairing, and alteration of the nucleotide sequence (without disruption of base-pairing) proximal to the cleavage site result in aberrant cleavage. Thus, the identity of the nucleotides near the cleavage site is important for recognition of the cleavage site rather than base-pairing. The important nucleotides are those at positions -2, -1, +1, +72, +73 and +74. We propose that the nucleotide at position +1 functions as a guiding nucleotide. These results raise the possibility that Mg2+ binding near the cleavage site is dependent on the identity of the nucleotides at these positions. In addition, we show that disruption of base-pairing in the acceptor-stem affects both Michaelis-Menten constants, Km and kcat.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
ARN Bacteriano
/
Precursores del ARN
/
ARN de Transferencia de Tirosina
/
ARN Catalítico
/
Proteínas de Escherichia coli
/
Endorribonucleasas
/
Escherichia coli
Idioma:
En
Revista:
J Mol Biol
Año:
1992
Tipo del documento:
Article
País de afiliación:
Suecia