Dissection of Connective Beta -Strand Linkers and Their Role in Enzymatic Activities of Escherichia Coli Leucyl -Trna Synthetase

Mascarenhas, Anjali Paulette

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Description

Title

Dissection of Connective Beta -Strand Linkers and Their Role in Enzymatic Activities of Escherichia Coli Leucyl -Trna Synthetase

Author(s)

Mascarenhas, Anjali Paulette

Issue Date

2008

Doctoral Committee Chair(s)

Martinis, Susan A.

Department of Study

Biochemistry

Discipline

Biochemistry

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

Chemistry, Biochemistry

Language

eng

Abstract

Individual glycine residues, when mutated to proline, misaminoacylate tRNALeu in spite of retaining efficient amino acid editing activities. It is possible that these mutant LeuRSs may have impaired the translocation of editing substrates between the aminoacylation and editing active sites. An additional T252A mutation within the editing active site in the CP1 was combined with the translocation mutants and these double mutant LeuRSs were characterized in vitro and in vivo. The T252A mutant hydrolyzes both cognate and noncognate amino acids charged to tRNALeu, thereby significantly reducing the yield of charged tRNA. However, beta-strand-based mutants rescue leucylation activity of the T252A mutant LeuRS, suggesting an important role in the translocation pathway. Taken together, this investigation implies a more extensive role for the dynamic beta-strands at different steps of E. coli LeuRS enzyme activity.

Graduation Semester

2008

Type of Resource

text

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