Hypermutation in shark immunoglobulin light chain genes results in contiguous substitutions.
Among 631 substitutions present in 90 nurse shark immunoglobulin light chain somatic mutants, 338 constitute 2-4 bp stretches of adjacent changes. An absence of mutations in perinatal sequences and the bias for one mutating V gene in adults suggest that the diversification is antigen dependent. The substitutions shared no patterns, and the absence of donor sequences, including from family members, supports the idea that most changes arose from nontemplated mutation. The tandem mutations as a group are distinguished by consistently fewer transition changes and an A bias. We suggest this is one of several pathways of hypermutation diversifying shark antigen-receptor genes--point mutations, tandem mutations, and mutations with a G-C preference--that coevolved with or preceded gene rearrangement.
Lee
Susan S
SS
Department of Physiology and Pharmacology, The State University of New York Health Science Center at Brooklyn, Brooklyn, NY 11203, USA.
Tranchina
Daniel
D
Ohta
Yuko
Y
Flajnik
Martin F
MF
Hsu
Ellen
E
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D001483:Base Sequence; D018076:DNA, Complementary; D005785:Gene Conversion; D015870:Gene Expression; D005803:Genes, Immunoglobulin; D007147:Immunoglobulin Light Chains / Q000235:genetics*; D008297:Male; D008969:Molecular Sequence Data; D009154:Mutation; D017354:Point Mutation; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D012754:Sharks / Q000235:genetics* / Q000276:immunology
D018076:DNA, Complementary; D007147:Immunoglobulin Light Chains