Abstract
We reported that the activity of Arabidopsis protein tyrosine phosphatase (AtPTP1) is regulated by redox status of the non-catalytic cysteine 175 and a substitutional mutant C175S AtPTP1 was not inhibited by GSSG (the JSPPJ Annual Meeting, 2008). To elucidate whether C175 is redox-regulated in vivo, we investigated seed germination, a redox-regulated phenomenon, in transgenic plants over-expressing wild-type or C175S mutant AtPTP1. Seed germination of these plants was little affected by GSSG alone. The suppression of seed germination by ABA was enhanced with increasing AtPTP1 expression, and the suppressive effect was strongest when C175S was expressed. The suppression was reduced by GSSG, and the reducing effect was strongest in C175S plants. These suggest that AtPTP1 promotes the ABA-dependent suppression of seed germination and that the abolishment of the promotion is caused by direct inhibition pathway via C175 and suppressive pathway downstream of AtPTP1.
