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2cxi
From Proteopedia
(New page: 200px<br /><applet load="2cxi" size="450" color="white" frame="true" align="right" spinBox="true" caption="2cxi, resolution 1.94Å" /> '''Crystal Structure Of...) |
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| - | [[Image:2cxi.gif|left|200px]]<br /><applet load="2cxi" size=" | + | [[Image:2cxi.gif|left|200px]]<br /><applet load="2cxi" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="2cxi, resolution 1.94Å" /> | caption="2cxi, resolution 1.94Å" /> | ||
'''Crystal Structure Of An N-terminal Fragment Of The Phenylalanyl-tRNA Synthetase Beta-Subunit From Pyrococcus Horikoshii'''<br /> | '''Crystal Structure Of An N-terminal Fragment Of The Phenylalanyl-tRNA Synthetase Beta-Subunit From Pyrococcus Horikoshii'''<br /> | ||
==Overview== | ==Overview== | ||
| - | To achieve accurate aminoacylation of tRNAs with their cognate amino | + | To achieve accurate aminoacylation of tRNAs with their cognate amino acids, errors in aminoacylation are corrected by the "editing" mechanism in several aminoacyl-tRNA synthetases. Phenylalanyl-tRNA synthetase (PheRS) hydrolyzes, or edits, misformed tyrosyl-tRNA with its editing domain in the beta subunit. We report the crystal structure of an N-terminal fragment of the PheRS beta subunit (PheRS-beta(N)) from the archaeon, Pyrococcus horikoshii, at 1.94-A resolution. PheRS-beta(N) includes the editing domain B3/4, which has archaea/eukarya-specific insertions/deletions and adopts a different orientation relative to other domains, as compared with that of bacterial PheRS. Surprisingly, most residues constituting the editing active-site pocket were substituted between the archaeal/eukaryal and bacterial PheRSs. We prepared Ala-substituted mutants of P. horikoshii PheRS for 16 editing-pocket residues, of which 12 are archaea/eukarya-specific and four are more widely conserved. On the basis of their activities, Tyr-adenosine was modeled on the B3/4-domain structure. First, the mutations of Leu-202, Ser-211, Asp-234, and Thr-236 made the PheRS incorrectly hydrolyze the cognate Phe-tRNA(Phe), indicating that these residues participate in the Tyr hydroxy group recognition and are responsible for discrimination against Phe. Second, the mutations of Leu-168 and Arg-223, which could interact with the tRNA 3'-terminal adenosine, reduced Tyr-tRNA(Phe) deacylation activity. Third, the mutations of archaea/eukarya-specific Gln-126, Glu-127, Arg-137, and Asn-217, which are proximal to the ester bond to be cleaved, also reduced Tyr-tRNA(Phe) deacylation activity. In particular, the replacement of Asn-217 abolished the activity, revealing its absolute requirement for the catalysis. |
==About this Structure== | ==About this Structure== | ||
| - | 2CXI is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Pyrococcus_horikoshii Pyrococcus horikoshii]. Active as [http://en.wikipedia.org/wiki/Phenylalanine--tRNA_ligase Phenylalanine--tRNA ligase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=6.1.1.20 6.1.1.20] Full crystallographic information is available from [http:// | + | 2CXI is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Pyrococcus_horikoshii Pyrococcus horikoshii]. Active as [http://en.wikipedia.org/wiki/Phenylalanine--tRNA_ligase Phenylalanine--tRNA ligase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=6.1.1.20 6.1.1.20] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2CXI OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Pyrococcus horikoshii]] | [[Category: Pyrococcus horikoshii]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
| - | [[Category: RSGI, RIKEN | + | [[Category: RSGI, RIKEN Structural Genomics/Proteomics Initiative.]] |
[[Category: Sasaki, H.]] | [[Category: Sasaki, H.]] | ||
[[Category: Sekine, S.]] | [[Category: Sekine, S.]] | ||
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[[Category: structural genomics]] | [[Category: structural genomics]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 16:53:23 2008'' |
Revision as of 14:53, 21 February 2008
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Crystal Structure Of An N-terminal Fragment Of The Phenylalanyl-tRNA Synthetase Beta-Subunit From Pyrococcus Horikoshii
Overview
To achieve accurate aminoacylation of tRNAs with their cognate amino acids, errors in aminoacylation are corrected by the "editing" mechanism in several aminoacyl-tRNA synthetases. Phenylalanyl-tRNA synthetase (PheRS) hydrolyzes, or edits, misformed tyrosyl-tRNA with its editing domain in the beta subunit. We report the crystal structure of an N-terminal fragment of the PheRS beta subunit (PheRS-beta(N)) from the archaeon, Pyrococcus horikoshii, at 1.94-A resolution. PheRS-beta(N) includes the editing domain B3/4, which has archaea/eukarya-specific insertions/deletions and adopts a different orientation relative to other domains, as compared with that of bacterial PheRS. Surprisingly, most residues constituting the editing active-site pocket were substituted between the archaeal/eukaryal and bacterial PheRSs. We prepared Ala-substituted mutants of P. horikoshii PheRS for 16 editing-pocket residues, of which 12 are archaea/eukarya-specific and four are more widely conserved. On the basis of their activities, Tyr-adenosine was modeled on the B3/4-domain structure. First, the mutations of Leu-202, Ser-211, Asp-234, and Thr-236 made the PheRS incorrectly hydrolyze the cognate Phe-tRNA(Phe), indicating that these residues participate in the Tyr hydroxy group recognition and are responsible for discrimination against Phe. Second, the mutations of Leu-168 and Arg-223, which could interact with the tRNA 3'-terminal adenosine, reduced Tyr-tRNA(Phe) deacylation activity. Third, the mutations of archaea/eukarya-specific Gln-126, Glu-127, Arg-137, and Asn-217, which are proximal to the ester bond to be cleaved, also reduced Tyr-tRNA(Phe) deacylation activity. In particular, the replacement of Asn-217 abolished the activity, revealing its absolute requirement for the catalysis.
About this Structure
2CXI is a Single protein structure of sequence from Pyrococcus horikoshii. Active as Phenylalanine--tRNA ligase, with EC number 6.1.1.20 Full crystallographic information is available from OCA.
Reference
Structural and mutational studies of the amino acid-editing domain from archaeal/eukaryal phenylalanyl-tRNA synthetase., Sasaki HM, Sekine S, Sengoku T, Fukunaga R, Hattori M, Utsunomiya Y, Kuroishi C, Kuramitsu S, Shirouzu M, Yokoyama S, Proc Natl Acad Sci U S A. 2006 Oct 3;103(40):14744-9. Epub 2006 Sep 26. PMID:17003130
Page seeded by OCA on Thu Feb 21 16:53:23 2008
Categories: Phenylalanine--tRNA ligase | Pyrococcus horikoshii | Single protein | RSGI, RIKEN Structural Genomics/Proteomics Initiative. | Sasaki, H. | Sekine, S. | Yokoyama, S. | Aminoacyl-trna synthetase | Ligase | National project on protein structural and functional analyses | Nppsfa | Riken structural genomics/proteomics initiative | Rsgi | Structural genomics
