Simultaneous decrease in deamination of 5'-adenylic acid and 5'-deoxy-5'-S-isobutylthioadenosine in chick-embryo...

Area of Science:

• Biochemistry
• Virology
• Cell Biology

Background:

• Rous sarcoma virus (RSV) infection induces morphological transformation in chick embryo fibroblasts.
• Enzyme activity, particularly deaminases, can be altered during viral oncogenesis.

Purpose of the Study:

• To investigate the effect of RSV infection on the deamination rate of 5 -deoxy-5 -S-isobutylthioadenosine (iBuS5 'Ado).
• To determine if changes in deamination activity are related to viral infection or src gene expression.
• To characterize the enzymes responsible for iBuS5 'Ado deamination.

Main Methods:

• Measuring the deamination rate of iBuS5 'Ado in infected and uninfected chick embryo fibroblasts.
• Assessing adenosine deaminase and 5 '-adenylic acid deaminase activities.
• Enzyme characterization using molecular weight estimation and activity assays.

Main Results:

• RSV infection significantly reduced the deamination rate of iBuS5 'Ado.
• A concomitant decrease in adenosine deaminase and 5 '-adenylic acid deaminase activities was observed.
• The reduction in enzyme activity was attributed to the viral infection itself, independent of src gene expression.
• At least three enzymes/isoenzymes with molecular weights of 295,000, 121,000, and 37,000 were identified as responsible for iBuS5 'Ado deamination.
• Two of these enzymes were identified as 5 '-adenylic acid deaminase and a heavy form of adenosine deaminase.

Conclusions:

• Viral infection by Rous sarcoma virus alters purine metabolism by reducing the deamination of iBuS5 'Ado.
• The observed changes in deaminase activity are a consequence of the infection process.
• Specific enzymes, including 5 '-adenylic acid deaminase and adenosine deaminase, are involved in the deamination pathway affected by RSV.