Journal Article

Combining different proteomic approaches to resolve complexity of the milk protein fraction of dromedary, Bactrian camels and hybrids, from different regions of Kazakhstan

Martin, Patrice, Ryskaliyeva, Alma, Henry, Céline, Konuspayeva, Gaukhar, Faye, Bernard, Miranda, Guy

2018

Overview

Nutritional suitability of milk is not only related to gross composition, but is also strongly affected by the microheterogeniety of the protein fraction. Hence, to go further into the evaluation of the potential suitability of non-bovine milks in human/infant nutrition it is necessary to have a detailed characterization of their protein components. Combining proven proteomic approaches (SDS-PAGE, LC-MS/MS and LC-ESI-MS) and cDNA sequencing, we provide here in depth characterization of the milk protein fraction of dromedary and Bactrian camels, and their hybrids, from different regions of Kazakhstan. A total 391 functional groups of proteins were identified from 8 camel milk samples. A detailed characterization of 50 protein molecules, relating to genetic variants and isoforms arising from post-translational modifications and alternative splicing events, belonging to nine protein families (κ-, αs1-, αs2-, β-; and γ-CN, WAP, α-LAC, PGRP, CSA/LPO) was achieved by LC-ESI-MS. The presence of two unknown proteins UP1 (22,939 Da) and UP2 (23,046 Da) was also reported as well as the existence of a β-CN short isoform (946 Da lighter than the full-length β-CN), arising very likely in both genetic variants (A and B) from proteolysis by plasmin. In addition, we report, for the first time to our knowledge, the occurrence of a αs2-CN phosphorylation isoform with 12P groups within two recognition motifs, suggesting thereby the existence of two kinase systems involved in the phosphorylation of caseins in the mammary gland. Finally, we demonstrate that genetic variants, which hitherto seemed to be species- specific (e.g. β-CN A for Bactrian and β-CN B for dromedary), are in fact present both in Camel dromedarius and C. bactrianus.

• Publisher: Public Library of Science,Public Library of Science (PLoS)
• Subject: Alternative splicing / Animal genetics / Bacteria / Bactrian camel / Biology and Life Sciences / Camel's milk / Camelidae / Camels / Camelus bactrianus / Camelus dromedarius / Chemical properties / Computer Science / Domestication / Dromedary / Functional groups / Gel electrophoresis / Genetic aspects / Genetic diversity / Genetic variance / Genetics / Gram-positive bacteria / Health aspects / Human nutrition / Humanities and Social Sciences / Hybrids / Identification and classification / Infant nutrition / Isoforms / Kinases / Life Sciences / Mammary gland / Mass spectrometry / Medicine and Health Sciences / Methods / Milk / Milk proteins / Molecular chains / Nutrition / People and Places / Peptides / Phosphorylation / Physical Sciences / Physiological aspects / Plasmin / Post-translation / Protein families / Protein research / Protein separation / Proteins / Proteolysis / Proteomics / Scientific imaging / Sodium lauryl sulfate