Open AccessInduction of a Reductive Pathway for Deoxyribonucleotide Synthesis during Early Embryogenesis of the Sea Urchin
Author(s) -
J. M. Noronha,
Gerald H. Sheys,
John M. Buchanan
Publication year - 1972
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.69.8.2006
Subject(s) - ribonucleotide reductase , dithiothreitol , sea urchin , puromycin , biochemistry , biology , deoxyribonucleotides , human fertilization , enzyme , protein biosynthesis , ribonucleoside , reductase , de novo synthesis , rna , nucleotide , microbiology and biotechnology , protein subunit , genetics , gene
Cell-free extracts ofArbacia eggs (Arbacia punctulata ) apparently do not contain an enzymatic system for the reduction of ribonucleotides to deoxyribonucleotides. However, during an interval of 5 hr after fertilization at 23°, an enzymatic system is produced that is capable of catalyzing the reduction of CDP to dCDP in the presence of Mg2+ , ethylenediaminetetraacetate, ATP, and a reducing agent, dithiothreitol. The activity is first seen about 1 hr after fertilization, and reaches a peak at about 5 hr. The appearance of the ribonucleotide reductase is prevented by the addition of emetine or puromycin, inhibitors of protein synthesis, to the cells before fertilization. Inclusion of actinomycin D in the cell suspension at a concentration sufficient to inhibit synthesis of messenger RNA does not appreciably affect the production of the enzyme activity. Preexisting, maternal RNA is thus used for synthesis of reductase. Ribonucleotide reductase may, therefore, represent the first example of an enzyme system absent in unfertilized eggs that is produced in response to fertilization.