Reference "Molecular cloning of two novel rice cDNA sequences encoding putative calcium-dependent protein kinases"

Reference ID

371

Title

Molecular cloning of two novel rice cDNA sequences encoding putative calcium-dependent protein kinases

Source

Plant molecular biology, 1995, vol. 27, pp. 953-967

Authors (3)

Breviario-D	Morello-L
Giani-S

Abstract

We have isolated, from a cDNA library constructed from rice coleoptiles, two
sequences, OSCPK2 and OSCPK11, that encode for putative calcium-dependent
protein kinase (CDPK) proteins. OSCPK2 and OSCPK11 cDNAs are related to SPK,
another gene encoding a rice CDPK that is specifically expressed in developing
seeds [20]. OSCPK2 and OSCPK11-predicted protein sequences are 533 and 542 amino
acids (aa) long with a corresponding molecular mass of 59436 and 61079 Da
respectively. Within their polypeptide chain, they all contain those conserved
features that define a plant CDPK; kinase catalytic sequences are linked to a
calmodulin-like regulatory domain through a junction region. The calmodulin-like
regulatory domain of the predicted OSCPK2 protein contains 4 EF-hand calcium-
binding sites while OSCPK11 has conserved just one canonical EF-hand motif. In
addition, OSCPK2- and OSCPK11-predicted proteins contain, at their N-terminal
region preceding the catalytic domain, a stretch of 80 or 74 residues highly
rich in hydrophilic amino acids. Comparison of the NH2-terminal sequence of all
three rice CDPKs so far identified (OSCPK2, OSCPK11 and SPK) indicates the
presence of a conserved MGxxC(S/Q)xxT motif that may define a consensus signal
for N-myristoylation. OSCPK2 and OSCPK11 proteins are both encoded by a single-
copy gene and their polyadenylated transcripts are 2.4 and 3.5 kb long
respectively. OSCPK2 and OSCPK11 mRNAs are equally abundant in rice roots and
coleoptiles. A 12 h white light treatment of the coleoptiles reduces the amount
of OSCPK2 mRNA with only a slight effect on the level of OSCPK11 transcript.
With anoxic treatments, OSCPK2 mRNA level declined significantly and promptly
while the amount of OSCPK11 transcript remained constant.