Protein-Level Evidence of Novel β-Type Hemocyanin and Heterogeneous Subunit Usage in the Pacific Whiteleg Shrimp, Litopenaeus vannamei

The functional diversity of crustacean hemocyanins is broad, encompassing O2 delivery, innate immune response, metabolite storage, and osmolyte balance, all in a heterogeneous protein structure. As such, the sequence diversity of this class of proteins and its subunit composition are the focus of ma...

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Main Authors: Jason Wang, Michael Gregory Janech, Karen Gray Burnett
Format: Article
Language:English
Published: Frontiers Media S.A. 2019-11-01
Series:Frontiers in Marine Science
Subjects:
Online Access:https://www.frontiersin.org/article/10.3389/fmars.2019.00687/full
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author Jason Wang
Michael Gregory Janech
Karen Gray Burnett
author_facet Jason Wang
Michael Gregory Janech
Karen Gray Burnett
author_sort Jason Wang
collection DOAJ
description The functional diversity of crustacean hemocyanins is broad, encompassing O2 delivery, innate immune response, metabolite storage, and osmolyte balance, all in a heterogeneous protein structure. As such, the sequence diversity of this class of proteins and its subunit composition are the focus of many studies on crustacean adaptation to environmental challenges. Recent transcriptomic and genomic assemblies on the Pacific whiteleg shrimp Litopenaeus vannamei have identified unique isoforms of hemocyanin including an ancestral β-type subunit thought to be lost in penaeid shrimp. However, it is unknown the degree to which these isoforms are translated as proteins, and their abundances within the hemolymph. The present study uses proteomic approaches to characterize the protein-level abundance and organization of these hemocyanin isoforms within their native oligomeric structures. Fractions of each hemocyanin oligomeric form were purified by size-exclusion high performance liquid chromatography for identification of subunit isoforms using tandem mass spectrometry at < 1% protein false discovery rate. Data are available via ProteomeXchange with identifier PXD014575. Relative abundances of hemocyanin oligomers and monomeric subunits from hemolymph and fractions were also quantified by polyacrylamide gel electrophoresis with and without denaturation for comparison of subunit heterogeneity. Hemocyanin subunits were organized primarily as hexamers (95–99% relative abundance) as opposed to dodecamers. Ten unique hemocyanins predicted by transcriptome and genome assemblies were identified by tandem mass spectrometry in both oligomer fractions including the first protein-level evidence of a β-type subunit in penaeid shrimp. Identified hemocyanins mapped to four genomic scaffolds and had two or three exons. A single small (75 kDa) subunit constituted half or more of all isoforms identified in each oligomer. The dodecameric fraction exhibited greater subunit heterogeneity utilizing a significantly lower ratio (1.04:1) of small subunit to large subunit compared to hexamers (2.05:1). One isoform, XP_027232115.1, appeared to be more dominant within dodecamers than hexamers. The ability to distinguish and quantify hemocyanin isoforms within oligomeric structures will aid future studies linking hemocyanin genes to transcripts to function and physiology as well as offer insight into the evolutionary history of crustaceans.
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spelling doaj.art-582337fb1fc344c68dc09a89fa6163412022-12-22T01:13:08ZengFrontiers Media S.A.Frontiers in Marine Science2296-77452019-11-01610.3389/fmars.2019.00687471725Protein-Level Evidence of Novel β-Type Hemocyanin and Heterogeneous Subunit Usage in the Pacific Whiteleg Shrimp, Litopenaeus vannameiJason Wang0Michael Gregory Janech1Karen Gray Burnett2Grice Marine Lab, Department of Biology, College of Charleston, Charleston, SC, United StatesHollings Marine Lab, Department of Biology, College of Charleston, Charleston, SC, United StatesGrice Marine Lab, Department of Biology, College of Charleston, Charleston, SC, United StatesThe functional diversity of crustacean hemocyanins is broad, encompassing O2 delivery, innate immune response, metabolite storage, and osmolyte balance, all in a heterogeneous protein structure. As such, the sequence diversity of this class of proteins and its subunit composition are the focus of many studies on crustacean adaptation to environmental challenges. Recent transcriptomic and genomic assemblies on the Pacific whiteleg shrimp Litopenaeus vannamei have identified unique isoforms of hemocyanin including an ancestral β-type subunit thought to be lost in penaeid shrimp. However, it is unknown the degree to which these isoforms are translated as proteins, and their abundances within the hemolymph. The present study uses proteomic approaches to characterize the protein-level abundance and organization of these hemocyanin isoforms within their native oligomeric structures. Fractions of each hemocyanin oligomeric form were purified by size-exclusion high performance liquid chromatography for identification of subunit isoforms using tandem mass spectrometry at < 1% protein false discovery rate. Data are available via ProteomeXchange with identifier PXD014575. Relative abundances of hemocyanin oligomers and monomeric subunits from hemolymph and fractions were also quantified by polyacrylamide gel electrophoresis with and without denaturation for comparison of subunit heterogeneity. Hemocyanin subunits were organized primarily as hexamers (95–99% relative abundance) as opposed to dodecamers. Ten unique hemocyanins predicted by transcriptome and genome assemblies were identified by tandem mass spectrometry in both oligomer fractions including the first protein-level evidence of a β-type subunit in penaeid shrimp. Identified hemocyanins mapped to four genomic scaffolds and had two or three exons. A single small (75 kDa) subunit constituted half or more of all isoforms identified in each oligomer. The dodecameric fraction exhibited greater subunit heterogeneity utilizing a significantly lower ratio (1.04:1) of small subunit to large subunit compared to hexamers (2.05:1). One isoform, XP_027232115.1, appeared to be more dominant within dodecamers than hexamers. The ability to distinguish and quantify hemocyanin isoforms within oligomeric structures will aid future studies linking hemocyanin genes to transcripts to function and physiology as well as offer insight into the evolutionary history of crustaceans.https://www.frontiersin.org/article/10.3389/fmars.2019.00687/fullhemocyanincrustaceansubunit heterogeneitymass spectrometryproteomics
spellingShingle Jason Wang
Michael Gregory Janech
Karen Gray Burnett
Protein-Level Evidence of Novel β-Type Hemocyanin and Heterogeneous Subunit Usage in the Pacific Whiteleg Shrimp, Litopenaeus vannamei
Frontiers in Marine Science
hemocyanin
crustacean
subunit heterogeneity
mass spectrometry
proteomics
title Protein-Level Evidence of Novel β-Type Hemocyanin and Heterogeneous Subunit Usage in the Pacific Whiteleg Shrimp, Litopenaeus vannamei
title_full Protein-Level Evidence of Novel β-Type Hemocyanin and Heterogeneous Subunit Usage in the Pacific Whiteleg Shrimp, Litopenaeus vannamei
title_fullStr Protein-Level Evidence of Novel β-Type Hemocyanin and Heterogeneous Subunit Usage in the Pacific Whiteleg Shrimp, Litopenaeus vannamei
title_full_unstemmed Protein-Level Evidence of Novel β-Type Hemocyanin and Heterogeneous Subunit Usage in the Pacific Whiteleg Shrimp, Litopenaeus vannamei
title_short Protein-Level Evidence of Novel β-Type Hemocyanin and Heterogeneous Subunit Usage in the Pacific Whiteleg Shrimp, Litopenaeus vannamei
title_sort protein level evidence of novel β type hemocyanin and heterogeneous subunit usage in the pacific whiteleg shrimp litopenaeus vannamei
topic hemocyanin
crustacean
subunit heterogeneity
mass spectrometry
proteomics
url https://www.frontiersin.org/article/10.3389/fmars.2019.00687/full
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