15.5kD/Snu13/L7Ae protein: Difference between revisions
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A variation of the [[Kink-turn motif|kink-turn motif]], known as the kink-loop motif, can be found in the C/D and H/ACA RNAs <ref name ="gagnon"/>. Interestingly, the eukaryotic proteins and their archaeal homologue do not interact with the different motifs in the same manner, even though share a conserved sequence similarity <ref name ="oruganti"/>. For example, while L7Ae exhibits the same binding affinity for both the [[Kink-turn motif|kink-turn]] and kink-loop sRNA motifs, its eukaryotic homologues only bind specifically to the [[Kink-turn motif|kink-turn motif]] and discriminate against the kink-loop motif <ref name ="oruganti"/><ref name ="gagnon"/>. | A variation of the [[Kink-turn motif|kink-turn motif]], known as the kink-loop motif, can be found in the C/D and H/ACA RNAs <ref name ="gagnon"/>. Interestingly, the eukaryotic proteins and their archaeal homologue do not interact with the different motifs in the same manner, even though share a conserved sequence similarity <ref name ="oruganti"/>. For example, while L7Ae exhibits the same binding affinity for both the [[Kink-turn motif|kink-turn]] and kink-loop sRNA motifs, its eukaryotic homologues only bind specifically to the [[Kink-turn motif|kink-turn motif]] and discriminate against the kink-loop motif <ref name ="oruganti"/><ref name ="gagnon"/>. | ||
Solved structures of the proteins include: 15.5kD in complex with a U4 snRNA fragment [[ | Solved structures of the proteins include: | ||
*15.5kD in complex with a U4 snRNA fragment, [[1e7k]] | |||
*15.5kD in complex with hPrp31 and a U4 snRNA fragment [[2ozb]] | |||
*Snu13p without RNA - [[1zwz]] | |||
*''[http://en.wikipedia.org/wiki/Archaeoglobus Archaeoglobus fulgidus]'' L7Ae-box C/D with RNA [[1rlg]] | |||
*''[http://en.wikipedia.org/wiki/Methanococcus_jannaschii Methanococcus jannaschii]'' L7Ae-H/ACA with RNA [[1ra4]] | |||
*''[http://en.wikipedia.org/wiki/Pyrococcus Pyrococcus abyssi]'' L7Ae without RNA [[1pxw]]. | |||
=Role in pre-ribosomal RNA processing= | =Role in pre-ribosomal RNA processing= | ||
[[Ribosomes]] consist of both RNA and protein, and are designated large ribonucleprotein (RNP) particles. Each ribosome contains two subunits (60S and 40S), four ribosomal RNAs (5S, 5.8S, 18S, and 25/28S rRNA), and approximately 75 associated proteins <ref name ="venema">PMID:10690410</ref>. The processing of the pre-rRNAs requires a complex set of posttranscriptional modification steps after [http://en.wikipedia.org/wiki/Transcription_(genetics) transcription] <ref name ="venema"/>. One such step involves extensive processing through pseudouridylation and 2’-O-ribose methylation at sites specified by various [http://en.wikipedia.org/wiki/Small_nucleolar_RNA s(no)RNAs] (C/D box s(no)RNAs specify 2’-O-ribose methylation and H/ACA s(no)RNA specify pseudouridylation) and associated proteins to form s(no)RNPs <ref name ="venema"/><ref name ="m-g">PMID:12810916</ref>. Specifically, the 5’ region of U3 s(no)RNA containing C’/D and B/C box pairs interacts with 5’-ETS and 17S/18S areas of the pre-rRNA<ref name ="m-g"/>. U3 also binds a set of proteins to form the U3 s(no)RNP complex <ref name ="gagnon"/>. | [[Ribosome|Ribosomes]] consist of both RNA and protein, and are designated large ribonucleprotein (RNP) particles. Each ribosome contains two subunits (60S and 40S), four ribosomal RNAs (5S, 5.8S, 18S, and 25/28S rRNA), and approximately 75 associated proteins <ref name ="venema">PMID:10690410</ref>. The processing of the pre-rRNAs requires a complex set of posttranscriptional modification steps after [http://en.wikipedia.org/wiki/Transcription_(genetics) transcription] <ref name ="venema"/>. One such step involves extensive processing through pseudouridylation and 2’-O-ribose methylation at sites specified by various [http://en.wikipedia.org/wiki/Small_nucleolar_RNA s(no)RNAs] (C/D box s(no)RNAs specify 2’-O-ribose methylation and H/ACA s(no)RNA specify pseudouridylation) and associated proteins to form s(no)RNPs <ref name ="venema"/><ref name ="m-g">PMID:12810916</ref>. Specifically, the 5’ region of U3 s(no)RNA containing C’/D and B/C box pairs interacts with 5’-ETS and 17S/18S areas of the pre-rRNA<ref name ="m-g"/>. U3 also binds a set of proteins to form the U3 s(no)RNP complex <ref name ="gagnon"/>. | ||
Snu13p/15.5kD/L7Ae interacts with U3 s(no)RNA through a kink-turn RNA motif <ref name ="venema"/>. The protein initiates box C/D assembly by binding the kink-turn of the C/D RNAs <ref name ="gagnon"/>. Once the s(no)RNP is fully assembled the RNA regions bind to complementary regions in target pre-rRNA. This is followed by catalysis of the methyl transferase reaction by the associated proteins <ref name ="gagnon"/>. | Snu13p/15.5kD/L7Ae interacts with U3 s(no)RNA through a kink-turn RNA motif <ref name ="venema"/>. The protein initiates box C/D assembly by binding the kink-turn of the C/D RNAs <ref name ="gagnon"/>. Once the s(no)RNP is fully assembled the RNA regions bind to complementary regions in target pre-rRNA. This is followed by catalysis of the methyl transferase reaction by the associated proteins <ref name ="gagnon"/>. | ||