tRNA tertiary interactions. 2. Strategies to reach stability: The 15-48 Levitt base pair

BIOL 172

Romina Oliva, romina@chemistry.unina.it1, Luigi Cavallo, lcavallo@unisa.it2, and Anna Tramontano1. (1) Dipartimento di Scienze Biochimiche, Università di Roma ‘‘La Sapienza”, Piazzale Aldo Moro, 1Centro Linceo Interdisciplinare “Beniamino Segre”, Accademia dei Lincei, Roma, Italy, (2) Dipartimento di Chimica, Università di Salerno, Italy, Via Salvador Allende, Baronissi, Salerno, I-84081, Italy
The G15-C48 reverse Watson-Crick (RWC) base pair, also known as Levitt base pair, is one of the crucial tertiary interactions into the tRNA core. Among the nine yeast tRNAPhe tertiary interactions, however, G15-C48 represents the only base pair whose observed geometry does not correspond to an energy minimum. The stability of such tRNA tertiary interaction is thus “anomalously” dependent on the environment. In the best resolution structure now available for any tRNA, water molecules are found to bridge the G15 and C48 polar atoms and a divalent metal ion (Mg2+, Mn2+ or Co2+) is found coordinated to the G15 N7 atom. By quantum mechanics calculations we show here that a coordinate metal ion is able to effectively stabilize the G-C RWC geometry, whereas the bridging water molecules are less effective. A combined sequence analysis and quantum mechanics approach also allowed to outline an interesting alternative evolutionary strategy performed by archaeabacteria to reach the G15-C48 RWC base pair stability.
 

Chemistry and Metabolism
4:30 PM-6:30 PM, Tuesday, 12 September 2006 Moscone Center -- Hall D, Poster

Division of Biological Chemistry

The 232nd ACS National Meeting, San Francisco, CA, September 10-14, 2006