Thermodynamic analysis of a multifunctional RNA-binding protein, PhoRpp38, in the hyperthermophilic archaeon Pyrococcus horikoshii OT3

Abstract

The protein component PhoRpp38 of Pyrococcus horikoshii ribonuclease P (RNase P) is known to be a multifunctional RNA-binding protein. Previous biochemical data indicate that it binds to two stem-loops in RNase P RNA (PhopRNA). Thermodynamic analysis revealed that PhoRpp38 and PhopRNA interact with each other with an association constant (Ka) of 1.56 × 10 7 M -1. It was further found that PhoRpp38 simultaneously binds two stem-loop structures in PhopRNA with approximately equal affinity. Crystals of PhoRpp38 in complex with the stem-loop were grown and diffracted to a resolution of 7.0Å on a synchrotron X-ray source.