Eukaryotic initiation factor 4A is the component that interacts with ATP in protein chain initiation

Area of Science:

• Molecular Biology
• Biochemistry
• Plant Science

Background:

• Protein synthesis initiation is crucial for cellular function and requires multiple protein factors.
• Adenosine triphosphate (ATP) is essential for protein synthesis, but its direct binding partners among initiation factors were not fully elucidated.

Purpose of the Study:

• To identify the specific protein factor(s) involved in wheat germ protein synthesis that directly interact with ATP.
• To elucidate the role of ATP in the early stages of protein chain initiation.

Main Methods:

• Utilized ATP affinity analogue 5'-p-fluorosulfonylbenzoyladenosine (FSBA) to probe interactions with initiation factors.
• Employed substrate analogue 2',3'-O-(2,4,6-trinitrophenyl)adenosine 5'-triphosphate (TNP-ATP) to assess competitive inhibition and reversal.
• Investigated complex formation between ribosomes, mRNA, ATP, and eIF4A.

Main Results:

• Eukaryotic initiation factor 4A (eIF4A) activity was significantly inhibited by FSBA, while other factors remained unaffected.
• ATP, ADP, and AMP protected eIF4A from FSBA inactivation, with ATP showing specific protection at lower concentrations.
• TNP-ATP inhibited protein synthesis competitively with ATP, and this inhibition was reversed by adding eIF4A.

Conclusions:

• The primary interaction of ATP in wheat germ protein synthesis initiation occurs with eukaryotic initiation factor 4A (eIF4A).
• eIF4A plays a critical role in the ATP-dependent steps of mRNA-ribosome attachment during translation initiation.