Portal de Periódicos da CAPES

Structure of a bacterial ribonuclease P holoenzyme in complex with tRNA

2010; Nature Portfolio; Volume: 468; Issue: 7325 Linguagem: Inglês

10.1038/nature09516

1476-4687

Nicholas J. Reiter, Amy Osterman, Alfredo Torres‐Larios, Kerren K. Swinger, Tao Pan, Alfonso Mondragón,

Bacterial Genetics and Biotechnology

Ribonuclease (RNase) P is the universal ribozyme responsible for 5′-end tRNA processing. We report the crystal structure of the Thermotoga maritima RNase P holoenzyme in complex with tRNAPhe. The 154 kDa complex consists of a large catalytic RNA (P RNA), a small protein cofactor and a mature tRNA. The structure shows that RNA–RNA recognition occurs through shape complementarity, specific intermolecular contacts and base-pairing interactions. Soaks with a pre-tRNA 5′ leader sequence with and without metal help to identify the 5′ substrate path and potential catalytic metal ions. The protein binds on top of a universally conserved structural module in P RNA and interacts with the leader, but not with the mature tRNA. The active site is composed of phosphate backbone moieties, a universally conserved uridine nucleobase, and at least two catalytically important metal ions. The active site structure and conserved RNase P–tRNA contacts suggest a universal mechanism of catalysis by RNase P. Transfer RNAs are synthesized as precursors that require trimming at the 5' and 3' ends, and some modification of specific nucleotides. The ribozyme RNase P is universally responsible for processing the 5' end of tRNAs. The crystal structure of RNase P (from Thermotoga maritima) bound to mature phenylalanine transfer RNA has now been solved. It reveals the interactions involved in pre-tRNA recognition, active site location and the role of metals in catalysis. The RNase P–tRNA ribonucleoprotein structure also offers clues as to how an ancient RNA-based world might evolve to become the protein-catalyst dominated world of today. tRNAs are synthesized in a premature form that requires trimming of the 5′ and 3′ ends and modification of specific nucleotides. RNase P, a complex containing a long catalytic RNA and a protein cofactor, catalyses the cleavage that generates the mature 5′ end. Here, the structure of RNase P bound to mature tRNAPhe is solved. Recognition of the leader sequence and its mechanism of cleavage is determined by soaking an oligonucleotide corresponding to the premature 5′ end into the crystal.