Diversity of a ribonucleoprotein family in tobacco chloroplasts: two new chloroplast ribonucleoproteins and a phylogenetic tree of ten chloroplast RNA-binding domains.
Two new ribonucleoproteins (RNPs) have been identified from a tobacco chloroplast lysate. These two proteins (cp29A and cp29B) are nuclear-encoded and have a less affinity to single-stranded DNA as compared with three other chloroplast RNPs (cp28, cp31 and cp33) previously isolated. DNA sequencing revealed that both contain two consensus sequence-type homologous RNA-binding domains (CS-RBDs) and a very acidic amino-terminal domain but shorter than that of cp28, cp31 and cp33. Comparison of cp29A and cp29B showed a 19 amino acid insertion in the region separating the two CS-RBDs in cp29B. This insertion results in three tandem repeats of a glycine-rich sequence of 10 amino acids, which is a novel feature in RNPs. The two proteins are encoded by different single nuclear genes and no alternatively spliced transcripts could be identified. We constructed a phylogenetic tree for the ten chloroplast CS-RBDs. These results suggest that there is a sizable RNP family in chloroplasts and the diversity was mainly generated through a series of gene duplications rather than through alternative pre-mRNA splicing. The gene for cp29B contains three introns. The first and second introns interrupt the first CS-RBD and the third intron does the second CS-RBD. The position of the first intron site is the same as that in the human hnRNP A1 protein gene.
Ye
L H
LH
Center for Gene Research, Nagoya University, Japan.
Li
Y Q
YQ
Fukami-Kobayashi
K
K
Go
M
M
Konishi
T
T
Watanabe
A
A
Sugiura
M
M
D000595:Amino Acid Sequence; D001483:Base Sequence; D001665:Binding Sites; D002736:Chloroplasts / Q000737:chemistry*; D004247:DNA; D014644:Genetic Variation; D008969:Molecular Sequence Data; D010802:Phylogeny; D010940:Plant Proteins / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D010947:Plants, Toxic; D012313:RNA / Q000378:metabolism; D012091:Repetitive Sequences, Nucleic Acid; D012261:Ribonucleoproteins / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D016415:Sequence Alignment; D014026:Nicotiana / Q000737:chemistry / Q000235:genetics*
D010940:Plant Proteins; D012261:Ribonucleoproteins; C072047:CP29A protein, Nicotiana tabacum; C072048:CP29B protein, Nicotiana sylvestris; D012313:RNA; D004247:DNA