Activation of glycosylasparaginase. Formation of active N-terminal threonine by intramolecular autoproteolysis

The activation mechanism of glycosylasparaginase of Flavobacterium meningosepticum has been analyzed by site-directed mutagenesis and activation of purified precursors in vitro. Mutation of Thr-152 to Ser or Cys leads to gene products that are not activated in vivo but are activated in vitro because...

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Bibliographic Details
Published in:The Journal of biological chemistry 1996-01, Vol.271 (3), p.1732-1737
Main Authors: Guan, C, Cui, T, Rao, V, Liao, W, Benner, J, Lin, C L, Comb, D
Format: Article
Language:English
Subjects:
Amino Acid Sequence
Aspartylglucosylaminase - metabolism
Base Sequence
Enzyme Activation
Flavobacterium - enzymology
Flavobacterium meningosepticum
Kinetics
Mathematics
Models, Theoretical
Molecular Sequence Data
Mutagenesis, Site-Directed
Oligodeoxyribonucleotides
Point Mutation
Recombinant Proteins - metabolism
Thermodynamics
Threonine
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Summary:The activation mechanism of glycosylasparaginase of Flavobacterium meningosepticum has been analyzed by site-directed mutagenesis and activation of purified precursors in vitro. Mutation of Thr-152 to Ser or Cys leads to gene products that are not activated in vivo but are activated in vitro because processing of the mutant precursors is inhibited by certain amino acids in the cell. Kinetic studies reveal that activation is an intramolecular autoproteolytic process. The involvement of His-150 and Thr/Ser/Cys-152 in activation suggests that autoproteolysis resembles proteolysis by serine/cysteine proteases. Multiple functions of the highly conserved active threonine residue are implicated.
ISSN:0021-9258
DOI:10.1074/jbc.271.3.1732