Bacteriophage T4-coded dihydrofolate reductase: synthesis, turnover, and location of the virion protein.
AUTOR(ES)
Mosher, R A
RESUMO
Dihydrofolate reductase plays a dual role in bacteriophage T4, first, as an enzyme of thymidylate metabolism, and second, as a protein component of the tail baseplate. Antibody to the purified enzyme has been used to study its synthesis and intracellular turnover. The antibody specifically precipitates one protein from T4D-infected cell extracts. This has been identified as dihydrofolate reductase, although the polypeptide molecular weight (22,000) is lower than that earlier determined for this enzyme. The protein comigrates on gels with pY, a genetically undefined protein component of the baseplate. However, it is not pY, for pY is synthesized late in infection, whereas virtually no dihydrofolate reductase synthesis occurs later than 10 min after infection at 37 degrees C. Dihydrofolate reductase, once formed, is neither degraded nor converted to proteins of higher or lower molecular weight. Thus, it is probably incorporated into virions at the same molecular weight as that of the soluble enzyme. 125I-radiolabeled antibody binds to the wedge substructure of the baseplate, and this binding is blocked by preincubation with purified T4 dihydrofolate reductase. Thus, the enzyme protein seems to be a component of the wedge.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=353425Documentos Relacionados
- Bacteriophage T4 Virion Dihydrofolate Reductase: Approaches to Quantitation and Assessment of Function
- Bacteriophage T4 Virion Baseplate Thymidylate Synthetase and Dihydrofolate Reductase
- Bacteriophage T4 baseplate components. II. Binding and location of bacteriophage-induced dihydrofolate reductase.
- An immunoblot assay reveals that bacteriophage T4 thymidylate synthase and dihydrofolate reductase are not virion proteins.
- Control of synthesis of mRNA's for T4 bacteriophage-specific dihydrofolate reductase and deoxycytidylate hydroxymethylase.