Abstract
ACS is a rate-limiting enzyme of ethylene biosynthesis and regulates mainly transcriptionally. However, we had speculated that ACS is also regulated post-translationally and found that LE-ACS2 was phosphorylated and the half-life of phosphorylated LE-ACS2 was longer than that of dephosphorylated one, that is, the phosphorylation was involved in turnover. To elucidate the molecular mechanism of post-translational regulation by phosphorylation, we tried to identify the kinase that phosphorylates LE-ACS2. The cDNA libraries of wounded tomato fruits were constructed using ZAPII vector and infected E.coli BL21, in which LE-ACS2 can be expressed. cDNAs and LE-ACS2 were co-expressed by IPTG and clones that harbored kinases for LE-ACS2 were immuno-screening using the antibody, which can recognized phosphorylated LE-ACS2. As the result of screening, a certain CDPK was cloned. It was similar to NtCDPK2, induced by elicitors and osmotic stress. Now, we investigate biochemical characters and expression patterns of the CDPK.
