Dataset Information

Rapid, One-step Sample Processing for Label-Free Single-Cell Proteomics

ABSTRACT: Sample preparation for single-cell proteomics is generally performed in a one-pot workflow with multiple dispensing and incubation steps. These hours-long workflows can be labor intensive and lead to long sample-to-answer times. Here we report a sample processing method that achieves cell lysis, protein denaturation and digestion in one hour with a single reagent dispensing step using commercially available high-temperature-stabilized proteases. Four different one-step reagent compositions were evaluated, and the mixture providing greatest proteome coverage was compared to the previously employed multi-step workflow. The one-step preparation increases proteome coverage relative to the multi-step workflow while minimizing labor input and the possibility of human error. We also compared sample recovery between previously used microfabricated glass nanowell chips and injection-molded polypropylene substrates, and found the polypropylene provided improved proteome coverage. Combined, the one-step sample preparation and the polypropylene substrates enabled identification of an average of nearly 2,400 proteins per cell using a standard data-dependent workflow with an Orbitrap mass spectrometer. As such, these advances significantly simplify sample preparation for single-cell proteomics and broaden accessibility with no compromise in terms of proteome coverage.

INSTRUMENT(S): Orbitrap Eclipse, Orbitrap Exploris 480

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Epithelial Cell

SUBMITTER: Ryan Kelly

LAB HEAD: Dr Ryan T. Kelly

PROVIDER: PXD041879 | Pride | 2023-10-09

REPOSITORIES: Pride

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Rapid, One-Step Sample Processing for Label-Free Single-Cell Proteomics.

Johnston S Madisyn SM Webber Kei G I KGI Xie Xiaofeng X Truong Thy T Nydegger Alissia A Lin Hsien-Jung L HL Nwosu Andikan A Zhu Ying Y Kelly Ryan T RT

Journal of the American Society for Mass Spectrometry 20230706 8

Sample preparation for single-cell proteomics is generally performed in a one-pot workflow with multiple dispensing and incubation steps. These hours-long processes can be labor intensive and lead to long sample-to-answer times. Here we report a sample preparation method that achieves cell lysis, protein denaturation, and digestion in 1 h using commercially available high-temperature-stabilized proteases with a single reagent dispensing step. Four different one-step reagent compositions were eva ...[more]

PMID: 37410391

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Project description:The sensitivity of single-cell proteomics (SCP) has increased dramatically in recent years due to advances in experimental design, sample preparation, separations and mass spectrometry instrumentation. However, further increasing the sensitivity of SCP methods and instrumentation will enable the study of proteins within single cells that are expressed at copy numbers too small to be measured by current methods. Here we further increase SCP sensitivity by combining efficient nanoPOTS sample preparation and ultra-low-flow liquid chromatography with a newly developed data acquisition and analysis scheme termed wide window acquisition (WWA) to extend the achievable proteome coverage for single cells to >3,000 for single-cell data analyses. WWA is based on data-dependent acquisition (DDA) but employs larger precursor isolation windows to intentionally co-isolate and co-fragment additional precursors along with the selected precursor. The resulting chimeric MS2 spectra are then resolved using the CHIMERYS search engine within Proteome Discoverer 3.0. Compared to standard DDA workflows, WWA employing isolation windows of 8-12 Th increases peptide and proteome coverage by ~28% and ~39%, respectively. For a 40 min LC gradient operated at ~15 nL/min, we identified an average of 2,150 proteins per single-cell-sized aliquots of protein digest directly from MS2 spectra, which increased to an average 3,524 proteins including proteins identified with MS1-level feature matching. Reducing the active gradient to 20 min resulted in only a 10% decrease in proteome coverage. We also compared performance of WWA with DIA underperformed relative to WWA in terms of proteome coverage, especially with faster separations. Average proteome coverage for single HeLa and K562 cells was respectively 1,758 and 1,642 based on MS2 identifications with 1% false discovery rate and 3042 and 2891 with MS1 feature matching. As such, WWA combined with efficient sample preparation and rapid separations extends the depths of the proteome that can be studied at the single-cell level.

Project description:The analysis of single cell proteomes has recently become a viable complement to transcript and genomics studies. Proteins are the main driver of cellular functionality and mRNA levels are often an unreliable proxy of such. Therefore, the global analysis of the proteome is essential to study cellular identities. Both multiplexed and label-free mass spectrometry-based approaches with single cell resolution have lately attributed surprising heterogeneity to believed homogenous cell populations. Even though specialized experimental designs and instrumentation have demonstrated remarkable advances, the efficient sample preparation of single cells still lacks behind. Here, we introduce the proteoCHIP, a universal option for single cell proteomics sample preparation at surprising sensitivity and throughput. The automated processing using a commercial system combining single cell isolation and picoliter dispensing, the cellenONE®, allows to reduce final sample volumes to low nanoliters submerged in a hexadecane layer simultaneously eliminating error prone manual sample handling and overcoming evaporation. With this specialized workflow we achieved around 1,000 protein groups per analytical run at remarkable reporter ion signal to noise while reducing or eliminating the carrier proteome. We identified close to 2,000 protein groups across 158 multiplexed single cells from two highly similar human cell types and clustered them based on their proteome. In-depth investigation of regulated proteins readily identified one of the main drivers for tumorigenicity in this cell type. Our workflow is compatible with all labeling reagents, can be easily adapted to custom workflows and is a viable option for label-free sample preparation. The specialized proteoCHIP design allows for the direct injection of label-free single cells via a standard autosampler resulting in the recovery of 30% more protein groups compared to samples transferred to PEG coated vials. We therefore are confident that our versatile, sensitive, and automated sample preparation workflow will be easily adoptable by non-specialized groups and will drive biological applications of single cell proteomics.

			Action	DRS
	10ngQC_1.raw	Raw
	10ngQC_2.raw	Raw
	10ng_QC_1_channel2.raw	Raw
	10ng_QC_2_channel1.raw	Raw
	10ng_QC_3_channel2.raw	Raw