A role for [Fe4S4] clusters in tRNA recognition--a theoretical study.

Area of Science:

• Biochemistry
• Structural Biology
• Molecular Biology

Background:

• Iron-sulfur clusters are increasingly found in enzymes beyond their traditional roles.
• Their function in enzymes like tryptophanyl-tRNA synthetase (TmTrpRS) involved in protein biosynthesis is not fully understood.
• TmTrpRS from Thermotoga maritima presents a novel link between iron-sulfur cofactors, RNA, and protein synthesis.

Purpose of the Study:

• To investigate the role of the [Fe4S4] cluster in TmTrpRS for tRNA anticodon-loop recognition.
• To elucidate the structural and energetic basis for this interaction.
• To compare the findings with human tryptophanyl-tRNA synthetase.

Main Methods:

• Density functional theory (DFT) calculations.
• Structural comparison with human tryptophanyl-tRNA synthetase/tRNA complex.

Main Results:

• A specific structural motif involving a cysteine residue (R224) and polar main chain atoms was identified.
• This motif is proposed to recognize a 5' cytosine or 5' 2-thiocytosine in the tRNA anticodon loop.
• The motif confers both affinity and specificity, disfavoring binding of other bases like uracil.

Conclusions:

• The [Fe4S4] cluster in TmTrpRS is integral to specific tRNA recognition.
• This finding highlights an ancient mechanism connecting inorganic cofactors with the fundamental process of protein biosynthesis.
• The identified motif offers insights into the evolution of RNA-protein interactions.