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Heavy Chain V Region Diversity in the Duck-Billed Platypus (Ornithorhynchus anatinus): Long and Highly Variable Complementarity-Determining Region 3 Compensates for Limited Germline Diversity
journal contribution
posted on 2023-05-16, 13:33 authored by Johansson, J, Aveskogh, M, Munday, BL, Hellman, LIn this work, to study the emergence of the H chain V region repertoire during mammalian evolution, we present an analysis of 25 independent H chain V regions from a monotreme, the Australian duck-billed platypus, Ornithorhynchus anatinus. All the sequences analyzed were found to form a single branch within the clan III of mammalian V region sequences in a distance tree. However, compared with a classical V gene family this branch was more diversified in sequence. Sequence analysis indicates that the apparent lack of diversity in germline V segments is well compensated for by relatively long and highly diversified D and N nucleotides. In addition, extensive sequence variation was observed in the framework region 3. Furthermore, at least five and possibly seven different J segments seem to be actively used in recombination. Interestingly, internal cysteine bridges in the complementarity-determining region (CDR)3 loop, or between the CDR2 and CDR3 loops, are found in ∼ 36 % of the platypus V H sequences. Such cysteine bridges have also been observed in cow, camel, and shark. Internal cysteine bridges may play a role in stabilizing long and diversified CDR3 and thereby have a role in increasing the affinity of the Ab-Ag interaction.
History
Publication title
The Journal of ImmunologyVolume
168Pagination
5155-5162ISSN
0022-1767Department/School
School of Health SciencesPublisher
American Association of ImmunologistsPlace of publication
USARepository Status
- Restricted