Mollusk genes encoding lysine tRNA (UUU) contain introns.
New intron-containing genes encoding tRNAs were discovered when genomic DNA isolated from various animal species was amplified by the polymerase chain reaction (PCR) with primers based on sequences of rabbit tRNA(Lys). From sequencing analysis of the products of PCR, we found that introns are present in several genes encoding tRNA(Lys) in mollusks, such as Loligo bleekeri (squid) and Octopus vulgaris (octopus). These introns were specific to genes encoding tRNA(Lys)(CUU) and were not present in genes encoding tRNA(Lys)(CUU). In addition, the sequences of the introns were different from one another. To confirm the results of our initial experiments, we isolated and sequenced genes encoding tRNA(Lys)(CUU) and tRNA(Lys)(UUU). The gene for tRNA(Lys)(UUU) from squid contained an intron, whose sequence was the same as that identified by PCR, and the gene formed a cluster with a corresponding pseudogene. Several DNA regions of 2.1 kb containing this cluster appeared to be tandemly arrayed in the squid genome. By contrast, the gene encoding tRNA(Lys)(CUU) did not contain an intron, as shown also by PCR. The tRNA(Lys)(UUU) that corresponded to the analyzed gene was isolated and characterized. The present study provides the first example of an intron-containing gene encoding a tRNA in mollusks and suggests the universality of introns in such genes in higher eukaryotes.
Matsuo
M
M
Faculty of Bioscience and Biotechnology, Tokyo Institute of Technology, Yokohama, Japan.
Abe
Y
Y
Saruta
Y
Y
Okada
N
N
D000818:Animals; D000926:Anticodon / Q000235:genetics; D001483:Base Sequence; D003001:Cloning, Molecular; D049832:Decapodiformes / Q000235:genetics*; D005796:Genes / Q000235:genetics*; D007438:Introns / Q000235:genetics*; D008969:Molecular Sequence Data; D049831:Octopodiformes / Q000235:genetics*; D016133:Polymerase Chain Reaction / Q000379:methods; D011544:Pseudogenes / Q000235:genetics; D012357:RNA, Transfer, Lys / Q000235:genetics* / Q000302:isolation & purification; D011817:Rabbits; D017422:Sequence Analysis, DNA
D000926:Anticodon; D012357:RNA, Transfer, Lys