Cloning and characterization of cDNAs encoding S-RNases from almond (Prunus dulcis): primary structural features and sequence diversity of the S-RNases in Rosaceae.
cDNAs encoding three S-RNases of almond (Prunus dulcis), which belongs to the family Rosaceae, were cloned and sequenced. The comparison of amino acid sequences between the S-RNases of almond and those of other rosaceous species showed that the amino acid sequences of the rosaceous S-RNases are highly divergent, and intra-subfamilial similarities are higher than inter-subfamilial similarities. Twelve amino acid sequences of the rosaceous S-RNases were aligned to characterize their primary structural features. In spite of their high level of diversification, the rosaceous S-RNases were found to have five conserved regions, C1, C2, C3, C5, and RC4 which is Rosaceae-specific conserved region. Many variable sites fall into one region, named RHV. RHV is located at a similar position to that of the hypervariable region a (HVa) of the solanaceous S-RNases, and is assumed to be involved in recognizing S-specificity of pollen. On the other hand, the region corresponding to another solanaceous hypervariable region (HVb) was not variable in the rosaceous S-RNases. In the phylogenetic tree of the T2/S type RNase, the rosaceous S-RNase fall into two subfamily-specific groups (Amygdaloideae and Maloideae). The results of sequence comparisons and phylogenetic analysis imply that the present S-RNases of Rosaceae have diverged again relatively recently, after the divergence of subfamilies.
Ushijima
K
K
Kihara Institute for Biological Research and Graduate School of Integrated Science, Yokohama City University, Yokohama, Japan.
Sassa
H
H
Tao
R
R
Yamane
H
H
Dandekar
A M
AM
Gradziel
T M
TM
Hirano
H
H
D000595:Amino Acid Sequence; D015139:Blotting, Southern; D003001:Cloning, Molecular; D018076:DNA, Complementary; D008969:Molecular Sequence Data; D010802:Phylogeny; D011487:Protein Conformation; D012260:Ribonucleases / Q000737:chemistry* / Q000235:genetics*; D017386:Sequence Homology, Amino Acid; D014197:Trees / Q000235:genetics*
D018076:DNA, Complementary; D012260:Ribonucleases