In:
PLOS ONE, Public Library of Science (PLoS), Vol. 19, No. 6 ( 2024-6-7), p. e0291568-
Abstract:
Polymeric IgMs are secreted from plasma cells abundantly despite their structural complexity and intricate multimerization steps. To gain insights into IgM’s assembly mechanics that underwrite such high-level secretion, we characterized the biosynthetic process of a natural human IgM, SAM-6, using a heterologous HEK293(6E) cell platform that allowed the production of IgMs both in hexameric and pentameric forms in a controlled fashion. By creating a series of mutant subunits that differentially disrupt secretion, folding, and specific inter-chain disulfide bond formation, we assessed their effects on various aspects of IgM biosynthesis in 57 different subunit chain combinations, both in hexameric and pentameric formats. The mutations caused a spectrum of changes in steady-state subcellular subunit distribution, ER-associated inclusion body formation, intracellular subunit detergent solubility, covalent assembly, secreted IgM product quality, and secretion output. Some mutations produced differential effects on product quality depending on whether the mutation was introduced to hexameric IgM or pentameric IgM. Through this systematic combinatorial approach, we consolidate diverse overlapping knowledge on IgM biosynthesis for both hexamers and pentamers, while unexpectedly revealing that the loss of certain inter-chain disulfide bonds, including the one between μHC and λLC, is tolerated in polymeric IgM assembly and secretion. The findings highlight the differential roles of underlying non-covalent protein-protein interactions in hexamers and pentamers when orchestrating the initial subunit interactions and maintaining the polymeric IgM product integrity during ER quality control steps, secretory pathway trafficking, and secretion.
Type of Medium:
Online Resource
ISSN:
1932-6203
DOI:
10.1371/journal.pone.0291568
DOI:
10.1371/journal.pone.0291568.g001
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10.1371/journal.pone.0291568.g002
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10.1371/journal.pone.0291568.g003
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10.1371/journal.pone.0291568.g004
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10.1371/journal.pone.0291568.g005
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10.1371/journal.pone.0291568.g006
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10.1371/journal.pone.0291568.g007
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10.1371/journal.pone.0291568.g008
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10.1371/journal.pone.0291568.g009
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10.1371/journal.pone.0291568.g010
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10.1371/journal.pone.0291568.g011
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10.1371/journal.pone.0291568.g012
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10.1371/journal.pone.0291568.g013
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10.1371/journal.pone.0291568.g014
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10.1371/journal.pone.0291568.s001
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10.1371/journal.pone.0291568.s002
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10.1371/journal.pone.0291568.s003
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10.1371/journal.pone.0291568.s004
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10.1371/journal.pone.0291568.s005
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10.1371/journal.pone.0291568.s006
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10.1371/journal.pone.0291568.s007
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10.1371/journal.pone.0291568.s008
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10.1371/journal.pone.0291568.s009
DOI:
10.1371/journal.pone.0291568.s010
DOI:
10.1371/journal.pone.0291568.s011
DOI:
10.1371/journal.pone.0291568.s012
DOI:
10.1371/journal.pone.0291568.s013
DOI:
10.1371/journal.pone.0291568.s014
DOI:
10.1371/journal.pone.0291568.s015
DOI:
10.1371/journal.pone.0291568.s016
DOI:
10.1371/journal.pone.0291568.r001
DOI:
10.1371/journal.pone.0291568.r002
DOI:
10.1371/journal.pone.0291568.r003
DOI:
10.1371/journal.pone.0291568.r004
Language:
English
Publisher:
Public Library of Science (PLoS)
Publication Date:
2024
detail.hit.zdb_id:
2267670-3