tRNA Modification and Genetic Code Variations in Animal Mitochondria
Table 1
Relationship between the genetic code variations and modified nucleosides in the anticodon of the corresponding tRNAs in the animal phlyla.
(a) UGA codon.
Animal phyla
UGA specificity
Anticodon
Vertebrata
Trp
τm5UCA(a)
Tunicata (Urochordata)
Trp
τm5UCA(b)
Cephalochordata
Trp
(TCA)
Echinodermata
Trp
(TCA)
Arthropoda
Trp
U*CA(c)
Most invertebrate phyla
Trp
cmnm5(s2)UCA(d)
Platyhelminthes
Trp
(TCA)
Cnidaria, Placozoa, Porifera
Trp
(TCA)
(b) AUA codon.
Animal phyla
AUA specificity
Anticodon
Vertebrata
Met
f5CAU(e)
Tunicata (Urochordata)
Met
τm5UAU(f)
Cephalochordata
Met
(CAT)
Echinodermata
Ile
(GAT)
Arthropoda
Met
f5CAU(g)
Most invertebrate phyla
Met
f5CAU(h, i)
Platyhelminthes
Most (Echinostomida, Trematoda)
Met
(CAT)
Rhabditiophora, Planaria
Ile
(GAT)
Cnidaria
Ile
—(j)
Placozoa
Ile
(GAT)
Porifera
Ile
(CAT)(k)
(c) AAA codon.
Animal phyla
AAA specificity
Anticodon
Vertebrata
Lys
(CTT)
Tunicata (Urochordata)
Lys
(TTT)
Cephalochordata
Lys
(TTT)
Echinodermata
Asn
GΨU(l)
Arthropoda
Lys
CUU(m)/(TTT)
Most invertebrate phyla
Lys
(CTT/TTT)
Platyhelminthes
Asn
(GTT)
Cnidaria
Lys
—(j)
Placozoa
Lys
(TTT)
Porifera
Lys
(TTT)
(d) AGA/AGG codons.
Animal phyla
AGA/AGG specificity
Anticodon
Vertebrata
Term.
None
Tunicata (Urochordata)
Gly
τm5UCU(n)
Cephalochordata
Ser
(GCT)
Echinodermata
Ser
m7GCU(o)
Arthropoda
Most Arthropods
Ser
(GCT/TCT)
Drosophila melanogaster
Ser(p)
GCU(q)
Most invertebrate phyla
Ser
m7GCU(r)
Platyhelminthes
Ser
(GCT/TCT)
Cnidaria
Arg
—(j)
Placozoa
Arg
(TCT)
Porifera
Arg
(TCT)
In case that only the tRNA gene sequences are known, the anticodon sequences at DNA level are shown in parentheses. (a)Homo sapiens (Suzuki et al. [39]) (b)Halocynthia roretzi (Suzuki et al. [23]) (c)Drosophila melanogaster (Tomita et al. [12]). U* is an unkown modified uridine. (d)Ascaris suum (Sakurai et al. [15]) (e)Bos taurus (Moriya et al. [9]) (f)Halocynthia roretzi (Suzuki et al. [23]) (g)Drosophila melanogaster (Tomita et al. [12]) (h)Loligo bleekeri (Tomita et al. [30]) (i)Ascaris suum (Watanabe al. [31]) (j)Corresponding tRNA gene is not encoded in the mitochondrial genome. The tRNA decoding this codon is presumed to be imported from cytoplasm [40]. (k)Poriferan mt genomes encode three tRNA genes with anticodon CAT at DNA level. One of these tRNA is thought to be gene (L is the modified C (lysidine) found at the anticodon first position of most bacterial decoding AUA codon) [41]. (l)Asterias amurensis (Tomita et al. [42]) (m)Drosohila melanogaster (Tomita et al. [12]) (n)Halocynthia roretzi (Kondow et al. [29], Suzuki et al. [23]) (o)Asterias amurensis (Matsuyama et al. [10]) (p)No AGG codon appears in the D. melanogaster mitochondrial genome. (q)Drosophila melanogaster (Tomita et al. [12]) (r)Loligo bleekeri (Tomita et al. [11]).