A new member of the cytosolic O‐acetylserine(thiol)lyase gene family in Arabidopsis thaliana

Abstract
A cDNA, Atcys‐3A, encoding O‐acetylserine‐(thiol)lyase has been isolated from Arabidopsis thaliana. The deduced peptide sequence showed a high level of similarity with the bacterial counterpart, and a remarkable percentage of identity with other higher plant O‐acetylserine(thiol)lyase genes. Sequence comparision and Southern blot analysis suggested that Atcys‐3A was a new and different to the previously reported member of the cytosolic gene family in Arabidopsis. The Atcys‐3A expression was activated by sulfur limitation, requiring a carbon and nitrogen source for maximal expression. A similar pattern of regulation was observed at the O‐acetylserine(thiol)lyase activity level. Northern blot analysis also showed an organ‐specific expression of Atcys‐3A.