Quantitative comparison of manuka and clover honey proteomes with royal jelly

Abstract

Royal jelly and honey are two substances produced successively by the worker bee caste. Sequential window acquisition of all theoretical fragment-ion spectra mass spectrometry (SWATH-MS) was used to compare protein quantities of bee origin in manuka and clover honey to royal jelly. Two analysis techniques identified 75 proteins in total. Peptide intensity was directly compared for a subset of 32 proteins that were identified with high confidence, and the relative changes in protein abundance were compared between each honey and royal jelly. A total of 16 proteins were found only in honey, 9 of which were common to manuka and clover honeys, and 7 found only in manuka honey. None of the identified proteins were unique to clover honey, while four proteins were unique to royal jelly. Major Royal Jelly Proteins (MRJPs) had similar profiles in both honeys, except MRJP6, which was significantly more abundant in clover honey. Quantitative data suggests changes of the protein composition as bees develop through the worker caste, with subtle changes in MRJP amounts, and extensive changes in proteins with enzymatic function. Metabolism enzymes were more abundant in honey than in royal jelly, where the trend revealed a potential catalytic role for two uncharacterised proteins (MRJP6 and LOC408608). Differences in the proteomes of the two types of honey probably reflects differences in the type of nectar foraged.