Int. J. Integ. Biol., 2009, 6(5): 27-32Biochemical characterization of gamma-aminobutyric acid (GABA):pyruvate transaminase during rice leaf senescenceAnsari MI, Chen SGSenescence-associated genes (SAGs) are up-regulated
during plant senescence and may have been implicated in encoding enzymes
involved in metabolism of senescence tissues. The gene Osl2 (GABA:pyruvate-transaminase)
which is upregulated during leaf senescence in rice (Oryza sativa) was
functionally characterized. The recombinant Osl2 fusion protein over-expressed
in Escherichia coli displays pyruvate-dependent gamma-aminobutyric acid
(GABA) transaminase (EC 2.6.1.19) activity. Investigations of the corresponding
pyruvate-dependent GABA transaminase activities in rice leaves demonstrate the
up-regulation of enzyme activity during leaf senescence, with the highest
activity at the S3 stage of rice leaf senescence. Here we have discussed the
role of GABA:pyruvate-transaminase in the metabolism of amino acids and
nitrogen recycle during rice leaf senescence.
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