A NEW MEMBER OF THE CYTOSOLIC O-ACETYLSERINE(THIOL)LYASE GENE FAMILY IN ARABIDOPSIS-THALIANA

A cDNA, Atcys-3A, encoding O-acetylserine(thiol)lyase has been isolate d from Arabidopsis thaliana. The deduced peptide sequence showed a hig h level of similarity with the bacterial counterpart, and a remarkable percentage of identity with other higher plant O-acetylserine(thiol)l yase genes. Sequence comparision and Southern blot analysis suggested that Atcys-3A was a new and different to the previously reported membe r of the cytosolic gene family in Arabidopsis. The Atcys-3A expression was activated by sulfur limitation, requiring a carbon and nitrogen s ource for maximal expression, A similar pattern of regulation was obse rved at the O-acetylserine(thiol)lyase activity level. Northern blot a nalysis also showed an organ-specific expression of Atcys-3A.