國立高雄大學圖資館 |

登入

回首頁

The anomalous behavior of archaeal-type prolyl-tRNA synthetases.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	The anomalous behavior of archaeal-type prolyl-tRNA synthetases.
作者:	Srihari, Shipra Bunjun.
面頁冊數:	122 p.
附註:	Director: Dieter Soll.
附註:	Source: Dissertation Abstracts International, Volume: 64-10, Section: B, page: 4924.
Contained By:	Dissertation Abstracts International64-10B.
標題:	Chemistry, Biochemistry.
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3109467
ISBN:	0496570099

The anomalous behavior of archaeal-type prolyl-tRNA synthetases.
Srihari, Shipra Bunjun.

The anomalous behavior of archaeal-type prolyl-tRNA synthetases. [electronic resource] - 122 p.

Director: Dieter Soll.

Thesis (Ph.D.)--Yale University, 2003.

Aminoacyl-tRNA synthetases are essential for protein synthesis in the cell. The absence of cysteinyl-tRNA synthetase homologues in some archaeal genomes raises the possibility of a novel mechanism for cysteinyl-tRNA formation in these organisms. Prolyl-tRNA synthetase (ProRS) was suggested as the enzyme responsible for Cys-tRNACys formation in the archaea Methanocaldococcus jannaschii and Methanothermobacter thermautotrophicus , and a homologous ProRS was subsequently found in the deep-rooted eukaryote Giardia lamblia (described in this thesis), other archaea, and various bacterial species. Further analyses of ProRS function revealed their inability to catalyze the formation of a correct Cys-tRNA Cys product; instead, cysteinylation was occurring on the non-cognate tRNAPro. This thesis addresses questions prompted by the finding of efficient misacylation of cysteine onto tRNAPro. Though most aminoacyl-tRNA synthetases (AARSs) are able to hydrolyze non-cognate amino acids activated or charged onto tRNA, this study demonstrates the absence of editing mechanisms in an archaeal-type ProRS. M. jannaschii ProRS was unable to deacylate mischarged cysteine from tRNAPro. This finding implies that M. jannaschii ProRS was unable to distinguish cysteine from its cognate amino acid proline. Subsequent mutational analyses of the active site of this enzyme revealed the difficulty in disengaging the binding of cysteine and proline, and raise questions regarding the in vivo occurrence of cysteine mischarging. Lysyl-tRNA synthetases (LysRSs) provide another example of an unusual occurrence within the realm of aminoacyl-tRNA synthesis. LysRSs are unique in that they violate the class rule and exist as both class I and class II AARSs. Comparison of tRNA recognition by class I Borrelia burgdorferi LysRS and class II Escherichia coli LysRS with E. coli tRNA Lys mutants revealed that both enzymes recognize similar elements within their tRNA substrate. A G2·U71 wobble pair of the B. burgdorferi tRNALys, though tolerated by class I LysRS, acted as an anti-determinant for the class II E. coli LysRS. This difference in tRNA recognition displays a preference for the class I LysRS in the presence of a tRNA substrate with the G2·U71 wobble pair, and thus provides a molecular basis for the observed displacement of class II LysRS by class I LysRS in certain bacteria, such as the spirochete B. burgdorferi.

ISBN: 0496570099Subjects--Topical Terms:

226900
Chemistry, Biochemistry.

The anomalous behavior of archaeal-type prolyl-tRNA synthetases.
LDR:03365nmm _2200253 _450 001 162299
005 20051017073431.5
008 230606s2003 eng d
020 $a 0496570099
035 $a 00148800
035 $a 162299
040 $a UnM $c UnM
100 0 $a Srihari, Shipra Bunjun. $3 227426
245 1 4 $a The anomalous behavior of archaeal-type prolyl-tRNA synthetases. $h [electronic resource]
300 $a 122 p.
500 $a Director: Dieter Soll.
500 $a Source: Dissertation Abstracts International, Volume: 64-10, Section: B, page: 4924.
502 $a Thesis (Ph.D.)--Yale University, 2003.
520 # $a Aminoacyl-tRNA synthetases are essential for protein synthesis in the cell. The absence of cysteinyl-tRNA synthetase homologues in some archaeal genomes raises the possibility of a novel mechanism for cysteinyl-tRNA formation in these organisms. Prolyl-tRNA synthetase (ProRS) was suggested as the enzyme responsible for Cys-tRNACys formation in the archaea Methanocaldococcus jannaschii and Methanothermobacter thermautotrophicus , and a homologous ProRS was subsequently found in the deep-rooted eukaryote Giardia lamblia (described in this thesis), other archaea, and various bacterial species. Further analyses of ProRS function revealed their inability to catalyze the formation of a correct Cys-tRNA Cys product; instead, cysteinylation was occurring on the non-cognate tRNAPro. This thesis addresses questions prompted by the finding of efficient misacylation of cysteine onto tRNAPro. Though most aminoacyl-tRNA synthetases (AARSs) are able to hydrolyze non-cognate amino acids activated or charged onto tRNA, this study demonstrates the absence of editing mechanisms in an archaeal-type ProRS. M. jannaschii ProRS was unable to deacylate mischarged cysteine from tRNAPro. This finding implies that M. jannaschii ProRS was unable to distinguish cysteine from its cognate amino acid proline. Subsequent mutational analyses of the active site of this enzyme revealed the difficulty in disengaging the binding of cysteine and proline, and raise questions regarding the in vivo occurrence of cysteine mischarging. Lysyl-tRNA synthetases (LysRSs) provide another example of an unusual occurrence within the realm of aminoacyl-tRNA synthesis. LysRSs are unique in that they violate the class rule and exist as both class I and class II AARSs. Comparison of tRNA recognition by class I Borrelia burgdorferi LysRS and class II Escherichia coli LysRS with E. coli tRNA Lys mutants revealed that both enzymes recognize similar elements within their tRNA substrate. A G2·U71 wobble pair of the B. burgdorferi tRNALys, though tolerated by class I LysRS, acted as an anti-determinant for the class II E. coli LysRS. This difference in tRNA recognition displays a preference for the class I LysRS in the presence of a tRNA substrate with the G2·U71 wobble pair, and thus provides a molecular basis for the observed displacement of class II LysRS by class I LysRS in certain bacteria, such as the spirochete B. burgdorferi.
590 $a School code: 0265.
650 # 0 $a Chemistry, Biochemistry. $3 226900
710 0 # $a Yale University. $3 212430
773 0 # $g 64-10B. $t Dissertation Abstracts International
790 $a 0265
790 1 0 $a Soll, Dieter, $e advisor
791 $a Ph.D.
792 $a 2003
856 4 0 $u http://libsw.nuk.edu.tw/login?url=http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3109467 $z http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3109467