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Screening for phenotypic outliers identifies an unusually low concentration of a β-lactoglobulin B protein isoform in bovine milk caused by a synonymous SNP
BACKGROUND: Milk samples from 10,641 dairy cattle were screened by a mass spectrometry method for extreme concentrations of the A or B isoforms of the whey protein, β-lactoglobulin (BLG), to identify causative genetic variation driving changes in BLG concentration. RESULTS: A cohort of cows, from a...
Autores principales: | , , , , , , , , , , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
BioMed Central
2022
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8925192/ https://www.ncbi.nlm.nih.gov/pubmed/35296234 http://dx.doi.org/10.1186/s12711-022-00711-z |
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author | Davis, Stephen R. Ward, Hamish E. Kelly, Van Palmer, David Ankersmit-Udy, Alexandra E. Lopdell, Thomas J. Berry, Sarah D. Littlejohn, Mathew D. Tiplady, Kathryn Adams, Linda F. Carnie, Katie Burrett, Alayna Thomas, Natalie Snell, Russell G. Spelman, Richard J. Lehnert, Klaus |
author_facet | Davis, Stephen R. Ward, Hamish E. Kelly, Van Palmer, David Ankersmit-Udy, Alexandra E. Lopdell, Thomas J. Berry, Sarah D. Littlejohn, Mathew D. Tiplady, Kathryn Adams, Linda F. Carnie, Katie Burrett, Alayna Thomas, Natalie Snell, Russell G. Spelman, Richard J. Lehnert, Klaus |
author_sort | Davis, Stephen R. |
collection | PubMed |
description | BACKGROUND: Milk samples from 10,641 dairy cattle were screened by a mass spectrometry method for extreme concentrations of the A or B isoforms of the whey protein, β-lactoglobulin (BLG), to identify causative genetic variation driving changes in BLG concentration. RESULTS: A cohort of cows, from a single sire family, was identified that produced milk containing a low concentration of the BLG B protein isoform. A genome-wide association study (GWAS) of BLG B protein isoform concentration in milk from AB heterozygous cows, detected a group of highly significant single nucleotide polymorphisms (SNPs) within or close to the BLG gene. Among these was a synonymous G/A variation at position + 78 bp in exon 1 of the BLG gene (chr11:103256256G > A). The effect of the A allele of this SNP (which we named B’) on BLG expression was evaluated in a luciferase reporter assay in transfected CHO-K1 and MCF-7 cells. In both cell types, the presence of the B’ allele in a plasmid containing the bovine BLG gene from -922 to + 898 bp (relative to the transcription initiation site) resulted in a 60% relative reduction in mRNA expression, compared to the plasmid containing the wild-type B sequence allele. Examination of a mammary RNAseq dataset (n = 391) identified 14 heterozygous carriers of the B’ allele which were homozygous for the BLG B protein isoform (BB’). The level of expression of the BLG B’ allele was 41.9 ± 1.0% of that of the wild-type BLG B allele. Milk samples from three cows, homozygous for the A allele at chr11:103,256,256 (B’B’), were analysed (HPLC) and showed BLG concentrations of 1.04, 1.26 and 1.83 g/L relative to a mean of 4.84 g/L in milk from 16 herd contemporaries of mixed (A and B) BLG genotypes. The mechanism by which B’ downregulates milk BLG concentration remains to be determined. CONCLUSIONS: High-throughput screening and identification of outliers, enabled the discovery of a synonymous G > A mutation in exon 1 of the B allele of the BLG gene (B’), which reduced the milk concentration of β-lactoglobulin B protein isoform, by more than 50%. Milk from cows carrying the B’ allele is expected to have improved processing characteristics, particularly for cheese-making. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12711-022-00711-z. |
format | Online Article Text |
id | pubmed-8925192 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2022 |
publisher | BioMed Central |
record_format | MEDLINE/PubMed |
spelling | pubmed-89251922022-03-23 Screening for phenotypic outliers identifies an unusually low concentration of a β-lactoglobulin B protein isoform in bovine milk caused by a synonymous SNP Davis, Stephen R. Ward, Hamish E. Kelly, Van Palmer, David Ankersmit-Udy, Alexandra E. Lopdell, Thomas J. Berry, Sarah D. Littlejohn, Mathew D. Tiplady, Kathryn Adams, Linda F. Carnie, Katie Burrett, Alayna Thomas, Natalie Snell, Russell G. Spelman, Richard J. Lehnert, Klaus Genet Sel Evol Research Article BACKGROUND: Milk samples from 10,641 dairy cattle were screened by a mass spectrometry method for extreme concentrations of the A or B isoforms of the whey protein, β-lactoglobulin (BLG), to identify causative genetic variation driving changes in BLG concentration. RESULTS: A cohort of cows, from a single sire family, was identified that produced milk containing a low concentration of the BLG B protein isoform. A genome-wide association study (GWAS) of BLG B protein isoform concentration in milk from AB heterozygous cows, detected a group of highly significant single nucleotide polymorphisms (SNPs) within or close to the BLG gene. Among these was a synonymous G/A variation at position + 78 bp in exon 1 of the BLG gene (chr11:103256256G > A). The effect of the A allele of this SNP (which we named B’) on BLG expression was evaluated in a luciferase reporter assay in transfected CHO-K1 and MCF-7 cells. In both cell types, the presence of the B’ allele in a plasmid containing the bovine BLG gene from -922 to + 898 bp (relative to the transcription initiation site) resulted in a 60% relative reduction in mRNA expression, compared to the plasmid containing the wild-type B sequence allele. Examination of a mammary RNAseq dataset (n = 391) identified 14 heterozygous carriers of the B’ allele which were homozygous for the BLG B protein isoform (BB’). The level of expression of the BLG B’ allele was 41.9 ± 1.0% of that of the wild-type BLG B allele. Milk samples from three cows, homozygous for the A allele at chr11:103,256,256 (B’B’), were analysed (HPLC) and showed BLG concentrations of 1.04, 1.26 and 1.83 g/L relative to a mean of 4.84 g/L in milk from 16 herd contemporaries of mixed (A and B) BLG genotypes. The mechanism by which B’ downregulates milk BLG concentration remains to be determined. CONCLUSIONS: High-throughput screening and identification of outliers, enabled the discovery of a synonymous G > A mutation in exon 1 of the B allele of the BLG gene (B’), which reduced the milk concentration of β-lactoglobulin B protein isoform, by more than 50%. Milk from cows carrying the B’ allele is expected to have improved processing characteristics, particularly for cheese-making. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12711-022-00711-z. BioMed Central 2022-03-16 /pmc/articles/PMC8925192/ /pubmed/35296234 http://dx.doi.org/10.1186/s12711-022-00711-z Text en © The Author(s) 2022 https://creativecommons.org/licenses/by/4.0/Open AccessThis article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/ (https://creativecommons.org/licenses/by/4.0/) . The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/ (https://creativecommons.org/publicdomain/zero/1.0/) ) applies to the data made available in this article, unless otherwise stated in a credit line to the data. |
spellingShingle | Research Article Davis, Stephen R. Ward, Hamish E. Kelly, Van Palmer, David Ankersmit-Udy, Alexandra E. Lopdell, Thomas J. Berry, Sarah D. Littlejohn, Mathew D. Tiplady, Kathryn Adams, Linda F. Carnie, Katie Burrett, Alayna Thomas, Natalie Snell, Russell G. Spelman, Richard J. Lehnert, Klaus Screening for phenotypic outliers identifies an unusually low concentration of a β-lactoglobulin B protein isoform in bovine milk caused by a synonymous SNP |
title | Screening for phenotypic outliers identifies an unusually low concentration of a β-lactoglobulin B protein isoform in bovine milk caused by a synonymous SNP |
title_full | Screening for phenotypic outliers identifies an unusually low concentration of a β-lactoglobulin B protein isoform in bovine milk caused by a synonymous SNP |
title_fullStr | Screening for phenotypic outliers identifies an unusually low concentration of a β-lactoglobulin B protein isoform in bovine milk caused by a synonymous SNP |
title_full_unstemmed | Screening for phenotypic outliers identifies an unusually low concentration of a β-lactoglobulin B protein isoform in bovine milk caused by a synonymous SNP |
title_short | Screening for phenotypic outliers identifies an unusually low concentration of a β-lactoglobulin B protein isoform in bovine milk caused by a synonymous SNP |
title_sort | screening for phenotypic outliers identifies an unusually low concentration of a β-lactoglobulin b protein isoform in bovine milk caused by a synonymous snp |
topic | Research Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8925192/ https://www.ncbi.nlm.nih.gov/pubmed/35296234 http://dx.doi.org/10.1186/s12711-022-00711-z |
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