Molecular cloning and characterization of StCDPK2, a cdpk isoform expressed in sprouting tubers,

GIAMMARIA V; GARGANTINI P; ULLOA, R M

Pinamar, Prov. Buenos Aires

Congreso; XLI reunión de SAIB; 2005

Sociedad Argentina de Investigación Bioquímica

Potato plants can be considered perennial due to its vegetetive reproduction. Growing potato tubers or freshly harvested mature tubers have a dormant apical bud. Normally, this dormancy is spontaneously broken after a period of maturation of the tuber, resulting in the growth of a new sprout. During tuberization, dormancy and sprouting of potato tubers, calcium dependent protein kinase isoforms, StCDPK1 and StCDPK2,are differentially expressed. We cloned the full-length sequence of StCDPK2. StCDPK2 encodes a 515 aminoacid polypeptide chain that has a catalytic serine/threonine protein kinase domain at the N-terminus and a calmodulin-like domain at the C-terminus. A junction domain lies between the kinase domain and the calmodulin-like domain. StCDPK2 has an N-terminal variable amino acid domain with myristoylation and palmitoylation consensus sequences. In vitro translation of StCDPK2 revealed that it encodes an active protein kinase with an apparent molecular weight of 54 KDa, that is specifically recognized by an anti-CDPK antibody from Medicago. StCDPK2 is not present in dormant tubers but its expression is induced upon the outbreaking of dormancy when