Modifying the sequence of an immunoglobulin V-gene alters the resulting pattern of hypermutation

Abstract

following correction should be noted. On page 2475, the second line of the left column that reads ". . . were reconstituted with aly͞aly BM cells after lethal irradiation" should read ". . . were reconstituted with aly͞ϩ BM cells after lethal irradiation."Immunology. In the article "Modifying the sequence of an immunoglobulin V-gene alters the resulting pattern of hypermutation," by Beatriz Goyenechea and César Milstein, which appeared in number 24, November 26, 1996, of Proc. Natl. Acad. Sci. USA (93, 13979-13984), the following revision should be noted: The formula at the bottom of the first column of page 13980 was misprinted. The correct formula is:FIG. 6. Three-dimensional structure of rQR1 in complex with FAD and NADP ϩ (12). The C-terminal 43 amino acids (232-274) are shown in red (Left), and have been truncated at the arrow (Right). Different colors of the backbone indicate the two different subunits. It can be seen that the truncated portion of QR2 is critical for binding of the pyrophosphate moiety of the NAD(P)H cofactor. Note that the contact regions between the enzyme and FAD are presumably preserved in QR2 (Right), consistent with the tight binding of FAD. The structural comparison between rQR1 and hQR2 is appropriate since the homology between rQR1 and hQR1 is very high (85% identity). CorrectionsProc. Natl. Acad. Sci. USA 94 (1997) ABSTRACT Affinity maturation of antibodies requires localized hypermutation and antigen selection. Hypermutation is particularly active in certain regions (notably the CDRs of light and heavy chains) due to the local accumulation of hot spots. We have now analyzed the role of individual nucleotides in the origin of hot spots and show that mutability is largely defined by the nucleotide sequence. We compared the mutability profile of wild-type and modified transgenes that contain silent mutations in the CDR1 segment. We found a new hot spot created at the third base of Ser-31 when its wild-type AGT codon was substituted by AGC. Two major hot spots associated with this AGC vanished when Ser-31 was encoded by the synonymous TCA. In addition to these, which were the most prominent changes, there were compensatory alterations in mutability of residues not directly related to the introduced silent mutations, so that the average hypermutation remained constant. Thus, mutations arising early in the immune response, even silent ones, could affect the mutability of critical residues and alter the pattern of affinity maturation. When analyzing hybridomas, we detected such alterations, but they seemed to better correlate with changes in average rather than local mutation rates. Overall, this paper shows how evolution could have optimized the mutability of individual residues to minimize deleterious mutations. Thus, the optimal strategy for affinity maturation may involve the incorporation of multiple point mutations before antigen selection of the relevant cells.

Origin and diversification of the clonogenic cell in multiple myeloma: lessons from the immunoglobulin repertoire

“…71,72 Generally, the nature of somatic mutations in hypermutating B cells indicates a preference for transitions over transversions with purines being preferentially targeted over pyrimidines, suggesting strand bias; mutations are concentrated mainly in CDRs and most often are single nucleotide substitutions. [72][73][74][75][76] However, investigators have reported deletions or insertions of base stretches of varying length in hypermutating B cells and have concluded that this is a byproduct of the somatic hypermutation machinery within the GC rather than a result of V(D)J recombination in earlier stages of B cell ontogeny. 77,78 Furthermore, it appears that several types of oncogene translocations and Ig HC/LC trancations in heavy chain disease and AL amyloidosis are the result of this phenomenon.…”

AID-GFP chimeric protein increases hypermutation of Ig genes with no evidence of nuclear localization

“…However, there is an interesting difference. In vivo, there are two mutational hot spots that revolve around the consensus motif GAGCT or TA when read in the coding strand (9)(10)(11). There is evidence that in vivo mutations occur in both strands and, therefore, the complementary sequences of those motifs are also (albeit to a lesser extent) mutational hot spots (12,13).…”

Antibodyomics: bioinformatics technologies for understanding B‐cell immunity to HIV‐1

“…Studies have shown that AID preferentially mutates a position at or around hotspot motifs,73, 74, 75 which are more frequently observed in the CDR regions than the framework regions 74, 76, 77. Moreover, targeted nucleotide positions have increased chances to generate transition mutations (A↔G, C↔T), which are generated more frequently than transversion mutations, such as A↔C, A↔T, C↔G, or G↔T 74.…”