Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.26.5 (RNase P)
 1,348 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Escherichia coli ribonuclease P (RNase P), a ribonucleoprotein complex which primarily functions in tRNA biosynthesis, is composed of a catalytic RNA subunit, M1 RNA, and a protein cofactor, C5 protein. The fluorescence emission spectrum of the single tryptophan residue-containing C5 protein exhibits maxima at 318 nm and 332 nm. Based on a comparison of the emission spectra of wild-type C5 protein and some of its mutant derivatives, we have determined that the 318 nm maximum could be the result of a complex formed in the excited state as a result of hydrophobic interactions between Trp109, Phe18 and Phe73. The analogous tryptophan fluorescence emission spectra of wild-type C5 protein and the barstar mutant W38F/W44F, taken together with the detailed structural information available for barstar, provide a possible explanation for the unusual emission spectrum of C5 protein.
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PMID:Fluorescence properties of a tryptophan residue in an aromatic core of the protein subunit of ribonuclease P from Escherichia coli. 913 9

The pre-tRNA processing enzyme ribonuclease P is a ribonucleoprotein. In Escherichia coli assembly of the holoenzyme involves binding of the small (119 amino acid residue) C5 protein to the much larger (377 nucleotide) P RNA subunit. The RNA subunit makes the majority of contacts to the pre-tRNA substrate and contains the active site; however, binding of C5 stabilizes P RNA folding and contributes to high affinity substrate binding. Here, we show that RNase P ribonucleoprotein assembly also influences the folding of C5 protein. Thermal melting studies demonstrate that the free protein population is a mixture of folded and unfolded conformations under conditions where it assembles quantitatively with the RNA subunit. Changes in the intrinsic fluorescence of a unique tryptophan residue located in the folded core of C5 provide further evidence for an RNA-dependent conformational change during RNase P assembly. Comparisons of the CD spectra of the free RNA and protein subunits with that of the holoenzyme provide evidence for changes in P RNA structure in the presence of C5 as indicated by previous studies. Importantly, monitoring the temperature dependence of the CD signal in regions of the holoenzyme spectra that are dominated by protein or RNA structure permitted analysis of the thermal melting of the individual subunits within the ribonucleoprotein. These analyses reveal a significantly higher Tm for C5 when bound to P RNA and show that unfolding of the protein and RNA are coupled. These data provide evidence for a general mechanism in which the favorable free energy for formation of the RNA-protein complex offsets the unfavorable free energy of structural rearrangements in the RNA and protein subunits.
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PMID:RNA-dependent folding and stabilization of C5 protein during assembly of the E. coli RNase P holoenzyme. 1675 Feb 20