Formycin 3' end modified tRNATrp. Recognition by avian myeloblastosis virus reverse transcriptase and primer function

Area of Science:

• Molecular Biology
• Biochemistry
• Virology

Background:

• Transfer RNA (tRNATrp) plays a crucial role in protein synthesis and as a primer for reverse transcription.
• Adenosine analogues can be incorporated into tRNATrp to investigate structure-function relationships.
• Avian Myeloblastosis Virus (AMV) reverse transcriptase utilizes tRNATrp for initiating DNA synthesis from viral RNA.

Purpose of the Study:

• To investigate the impact of 3' end modifications on tRNATrp aminoacylation and primer function.
• To determine if modified tRNATrp can still serve as a primer for AMV reverse transcriptase.
• To assess the effect of these modifications on the recognition of tRNATrp by AMV reverse transcriptase.

Main Methods:

• Chemical modification of the 3' end of primer tRNATrp with adenosine analogues (2'deoxyadenosine, 3'deoxyadenosine, 3' amino-3' deoxyadenosine, formycin).
• Aminoacylation assays using cognate aminoacyl-tRNA synthetase.
• DNA synthesis assays catalyzed by AMV reverse transcriptase using modified tRNATrp as a primer.
• Enzyme-tRNA complex formation studies to assess recognition.

Main Results:

• Modified tRNATrp molecules were successfully aminoacylated with tryptophan.
• Despite aminoacylation, modified tRNATrp failed to initiate DNA synthesis directed by 35S AMV RNA.
• AMV reverse transcriptase recognition of the modified tRNATrp, as indicated by enzyme-tRNA complex formation, was not impaired.

Conclusions:

• 3' end modifications of primer tRNATrp affect its ability to initiate DNA synthesis.
• The failure to initiate DNA synthesis is likely due to functional consequences of the modifications, not altered recognition by AMV reverse transcriptase.
• These findings provide insights into the specific structural requirements for primer function in reverse transcription.