Dataset Information

Expanding the Family of Extracellular Chaperones: Identification of Plasma Proteins with Chaperone Activity

ABSTRACT: Proteostasis, the balance of protein synthesis, folding and degradation, is essential to maintain cellular function and viability, and the many known intracellular chaperones are recognised as playing key roles in sustaining life. In contrast, the identity of constitutively secreted extracellular chaperones (ECs) and their physiological roles in extracellular proteostasis is less completely understood. In the current study we designed and implemented a novel strategy to discover new ECs present in human blood. This strategy was based on the well-known propensity of chaperones to bind to regions of hydrophobicity exposed on misfolding proteins. We attached a destabilised protein that misfolds at 37 oC to magnetic beads, and used this as "bait" to bind to potential EC proteins. The bait-bearing beads were incubated in human serum for 2 h at either 37 oC or 4 oC (the latter serving as a control, not expected to induce bait protein misfolding). Proteins eluted from the beads were analysed by mass spectrometry to identify individual proteins and their relative abundance in eluates from beads incubated at 37 oC versus 4 oC. A group of proteins significantly more abundant in the eluate from the beads incubated at 37 oC were selected for in vitro analysis of chaperone activity. It was shown that vitronectin and plasminogen activator-3 inhibited both the in vitro aggregation of the Alzheimer's peptide (Aβ1-42) to form fibrillar amyloid, and the aggregation of citrate synthase to form unstructured (amorphous) aggregates. In contrast, prothrombin, C1r, and C1s inhibited the aggregation of Aβ1-42 but did not inhibit citrate synthase aggregation. This study thus identified five novel and abundant putative ECs which may play important roles in the maintenance of extracellular proteostasis, and which apparently have differing abilities to inhibit the amorphous and amyloid-forming protein aggregation pathways.

INSTRUMENT(S): Q Exactive

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Blood Plasma

SUBMITTER: Albert Lee

LAB HEAD: Mark Wilson

PROVIDER: PXD027042 | Pride | 2021-09-24

REPOSITORIES: Pride

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Dataset's files

Source:

			Action	DRS
	190514_Mark_Wilson_Band0.msf	Msf
	190514_Mark_Wilson_Band0.mzML	Mzml
	190514_Mark_Wilson_Band0.mzid.gz	Mzid
	190514_Mark_Wilson_Band0.pdResult	Other
	190514_Mark_Wilson_Band0.raw	Raw

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Publications

Expanding the family of extracellular chaperones: Identification of human plasma proteins with chaperone activity.

Geraghty Nicholas J NJ Satapathy Sandeep S Kelly Megan M Cheng Flora F Lee Albert A Wilson Mark R MR

Protein science : a publication of the Protein Society 20211004 11

Proteostasis, the balance of protein synthesis, folding and degradation, is essential to maintain cellular function and viability, and the many known intracellular chaperones are recognized as playing key roles in sustaining life. In contrast, the identity of constitutively secreted extracellular chaperones (ECs) and their physiological roles in extracellular proteostasis is less completely understood. We designed and implemented a novel strategy, based on the well-known propensity of chaperones ...[more]

PMID: 34553437

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