Enzymes that interact with tRNA are often challenged with the complex task of identifying specific tRNAs from a pool of potential substrates with highly similar secondary and tertiary structures.  This task is accomplished in diverse ways, with some enzymes identifying specific sequences, while others recognize a unique tertiary fold.  The tRNA m1G9 methyltransferase (Trm10) and the tRNAHis guanylyltransferase (Thg1) apparently represent opposite ends of this spectrum in yeast, with Trm10 recognizing multiple tRNA substrates with little dependence on nucleotide sequence, while Thg1 is highly dependent on recognition of the histidine-specific GUG anticodon.  Yet, our investigations reveal a more complex picture, indicating more flexibility with respect to interaction with substrate tRNAs than initially suggested by patterns of known substrates.  We propose that these latent modes of substrate recognition are the foundation for participation of Trm10 and Thg1 in alternative activities, and describe their impact on newly discovered biological functions.

tRNA recognition by processing enzymes: Diverse mechanisms lead to unexpected functions

244th National Meeting (2012)

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