TY - JOUR
T1 - Functional expression and properties of the tRNA(Lys)-specific core anticodon nuclease encoded by Escherichia coli prrC
AU - Morad, I.
AU - Chapman-Shimshoni, D.
AU - Amitsur, M.
AU - Kaufmann, G.
PY - 1993
Y1 - 1993
N2 - Escherichia coli carrying the optional locus prr harbor a latent, tRNA(Lys)-specific anticodon nuclease, activated by the product of phage T4 stp. Anticodon nuclease latency is ascribed to the masking of prrC, implicated with the enzymatic activity, by flanking, type Ic DNA restriction modification genes (prrA, B and D-hsdM, S and R). Overexpression of plasmid- borne prrC elicited anticodon nuclease activity in uninfected E. coli. In vitro, the prrC-coded core activity was indifferent to a synthetic Stp polypeptide, GTP, ATP, and endogenous DNA, effectors that synergistically activate the latent enzyme. Several facts suggested that PrrC is highly labile in the absence of the masking proteins. The core activity decayed with t( 1/2 ) below 1 min at 30 °C, and the PrrC portion of a fusion protein was unstable. Moreover, expression of prrC from its own promoter at low plasmid copy number did not allow detection of core activity. Yet, it sufficed for establishment of a latent, T4-inducible enzyme when complemented by the masking Hsd proteins, which were provided by another replicon. Interaction between the antagonistic components of latent anticodon nuclease was also demonstrated immunochemically. The coupling of anticodon nuclease with a DNA restriction modification system may serve to ward off its inadvertent toxicity and maintain it as an antiviral contingency.
AB - Escherichia coli carrying the optional locus prr harbor a latent, tRNA(Lys)-specific anticodon nuclease, activated by the product of phage T4 stp. Anticodon nuclease latency is ascribed to the masking of prrC, implicated with the enzymatic activity, by flanking, type Ic DNA restriction modification genes (prrA, B and D-hsdM, S and R). Overexpression of plasmid- borne prrC elicited anticodon nuclease activity in uninfected E. coli. In vitro, the prrC-coded core activity was indifferent to a synthetic Stp polypeptide, GTP, ATP, and endogenous DNA, effectors that synergistically activate the latent enzyme. Several facts suggested that PrrC is highly labile in the absence of the masking proteins. The core activity decayed with t( 1/2 ) below 1 min at 30 °C, and the PrrC portion of a fusion protein was unstable. Moreover, expression of prrC from its own promoter at low plasmid copy number did not allow detection of core activity. Yet, it sufficed for establishment of a latent, T4-inducible enzyme when complemented by the masking Hsd proteins, which were provided by another replicon. Interaction between the antagonistic components of latent anticodon nuclease was also demonstrated immunochemically. The coupling of anticodon nuclease with a DNA restriction modification system may serve to ward off its inadvertent toxicity and maintain it as an antiviral contingency.
UR - http://www.scopus.com/inward/record.url?scp=0027724879&partnerID=8YFLogxK
M3 - מאמר
AN - SCOPUS:0027724879
VL - 268
SP - 26842
EP - 26849
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
SN - 0021-9258
IS - 36
ER -