Somatic Mutants and Antibody Diversity

Secher, David S.; Milstein, C.; Adetugbo, Kayode

doi:10.1111/j.1600-065x.1977.tb00382.x

Cited by 43 publications

(25 citation statements)

References 35 publications

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“…The corollary is that the frequency of deleterious mutations is much lower than the average. A second corollary is that as hypermutation proceeds, hot spots are likely to become ''colder'' (19). Somewhat surprisingly, we find also that some of the nucleotides become ''hotter,'' because loss of hot spots seems to be compensated by opposite changes elsewhere.…”

Section: Immunology: Goyenechea and Milsteinmentioning

confidence: 60%

“…Although long suspected (19), the existence of intrinsic hot spots was first deduced from a statistical analysis of independent repeats of silent mutations of a single antibody gene (20). The analysis of the hypermutation of transgenes provided not only definitive evidence for the presence of intrinsic hot spots but also a deeper understanding of their origin, as well as their potential functional importance.…”

mentioning

confidence: 99%

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

Goyenechea

Milstein

1996

Proc. Natl. Acad. Sci. U.S.A.

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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.

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Section: Immunology: Goyenechea and Milsteinmentioning

confidence: 60%

mentioning

confidence: 99%

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

Goyenechea

Milstein

1996

Proc. Natl. Acad. Sci. U.S.A.

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“…If one attempts to predict the structure of H chain DNA on the basis of the characterized H chain mutants, it seems likely that recombination or splicing sites may exist not only at the VC joining region but also at the beginning and end of the hinge. In addition, results with other rarer or less well characterized human variants (1) and several murine proteins (30) suggest that each of the domains may correspond to a separate transcriptional unit defined in terms of excision and splicing of heterogeneous nuclear RNA.…”

Section: Resultsmentioning

confidence: 99%

Human heavy chain disease protein WIS: implications for the organization of immunoglobulin genes.

Prelli¹,

Frangione²

1979

Proc. Natl. Acad. Sci. U.S.A.

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Protein WIS is a human y3 heavy (H) chain disease immunoglobulin variant whose amino acid sequence is most readily interpreted by postulating that three residues of the amino terminus are followed by a deletion of most of the variable (VH) domain, which ends at the variable-constant (VC) joining region. Then there is a stretch of eight residues, three of which are unusual, while the other five have striking homology to the VC junction sequence. This is followed by a second deletion, which ends at the beginning of the quadruplicated hinge region. These findings are consistent with mutations resulting in deletions of most of the gene coding for the V region and CHI domain followed by splicing at the VC joining region and at the hinge. These structural features fit well the notion of genetic discontinuity between V and C genes and also suggest similar mechanisms of excision and splicing in the interdomain regions of the C gene of the heavy chain.Amino acid sequence studies of heavy chain disease (HCD) proteins and other immunoglobulin variants have demonstrated that most often these molecules contain deletions and that the deletions are not xandom but frequently involve immunoglobulin domains (1). In particular, in all but one of the y HCD proteins for which degradation can be definitively excluded, the deletion encompasses part of the variable (V) region and all of the CH1 domain of the constant (C) region, with resumption of normal sequence at the beginning of an unusual region known as the hinge, which contains the interchain disulfide bridges. The hinge varies for each class and subclass, is rich in cysteine and proline, has little homology with any heavy (H) chain domain, and can undergo duplications. Three yl myeloma proteins with internal deletions were recognized because of their dissociability under nonreducing conditions, and it was shown that only the hinge region from residues 216-230 is missing (2-4; L. A. Steiner, personal communication). Two other myeloma proteins with internal gaps in the light (L) chains (SAC and SM) have deletions of much of the variable region; the deletions end at points that may correspond to the VC joining region (5, 6).The present report presents detailed amino acid sequence studies of a y3 HCD protein WIS, which is of interest because the amino acid sequence is most consistent with the existence of an apparently normal amino-terminal sequence followed by two large deletions of VH and CH1, which are separated by a small stretch with striking homology to the VC joining region of the H chain. The second deletion ends at the beginning of the quadruplicated hinge (7). Though the precise mechanism for the generation of these deletions remains to be worked out, these findings are consistent with the possible existence of transcriptional units corresponding to immunoglobulin domains. MATERIALS AND METHODSProtein WIS was isolated from the urine of a patient with HCD by precipitation with 60% saturated ammonium sulfate and purified by ion-exchange chromatography on DEAE-cellu...

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“…Each Ig chain consists of several similar compact domains, each comprising two twisted ␤ sheets stabilized by a single intradomain disulfide (1). IgG assembly is stabilized by an interchain disulfide between C L , the LC constant domain, and C H 1, the first HC constant domain (2). The C H 1 domain confers retention in the endoplasmic reticulum (ER) on unassembled HCs, and despite its high degree of similarity to other constant domains, only C H 1 is retarded in folding and is unable to cycle from the ER chaperone BiP (3).…”

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confidence: 99%

Cysteines in CH1 Underlie Retention of Unassembled Ig Heavy Chains

Elkabetz

Argon

Bar-Nun

2005

Journal of Biological Chemistry

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Conformation, structure, and oligomeric state of immunoglobulins not only control quality and functional properties of antibodies but are also critical for immunoglobulins secretion. Unassembled immunoglobulin heavy chains are retained intracellularly by delayed folding of the C H 1 domain and irreversible interaction of BiP with this domain. Here we show that the three C H 1 cysteines play a central role in immunoglobulin folding, assembly, and secretion. Remarkably, ablating all three C H 1 cysteines negates retention and enables BiP cycling and non-canonical folding and assembly. This phenomenon is explained by interdependent formation of intradomain and interchain disulfides, although both bonds are dispensable for secretion. Substituting Cys-195 prevents formation not only of the intradomain disulfide, but also of the interchain disulfide bond with light chain, BiP displacement, and secretion. Mutating the light chain-interacting Cys-128 hinders disulfide bonding of intradomain cysteines, allowing their opportunistic bonding with light chain, without hampering secretion. We propose that the role of C H 1 cysteines in immunoglobulin assembly and secretion is not simply to engage in disulfide bridges, but to direct proper folding and interact with the retention machinery.

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Somatic Mutants and Antibody Diversity

Cited by 43 publications

References 35 publications

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

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

Human heavy chain disease protein WIS: implications for the organization of immunoglobulin genes.

Cysteines in CH1 Underlie Retention of Unassembled Ig Heavy Chains

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