Towards functional proteomics of minority component of honeybee royal jelly: The effect of post‐translational modifications on the antimicrobial activity of apalbumin2

Abstract

This study illustrates multifunctionality of proteins of honeybee royal jelly (RJ) and how their neofunctionalization result from various PTMs of maternal proteins. Major proteins of RJ, designated as apalbumins belong to a protein family consisting of nine members with M(r) of 49-87 kDa and they are accompanied by high number of minority homologs derived from maternal apalbumins. In spite of many data on diversity of apalbumins, the molecular study of their individual minority homologous is still missing. This work is a contribution to functional proteomics of second most abundant protein of RJ apalbumin2 (M(r) 52.7 kDa). We have purified a minority protein from RJ; named as apalbumin2a, differ from apalbumin2 in M(r) (48.6 kDa), in N-terminal amino acids sequences - ENSPRN and in N-linked glycans. Characterization of apalbumin2a by LC-MALDI TOF/TOF MS revealed that it is a minority homolog of the major basic royal jelly protein, apalbumin2, carrying two fully occupied N-glycosylation sites, one with high-mannose structure, HexNAc2Hex9, and another carrying complex type antennary structures, HexNAc4Hex3 and HexNAc5Hex4. We have found that apalbumin2a inhibit growth of Paenibacillus larvae. The obtained data call attention to functional plasticity of RJ proteins with potential impact on functional proteomics in medicine.

Major royal jelly proteins as markers of authenticity and quality of honey / Glavni proteini matične mliječi kao markeri izvornosti i kakvoće meda

“…An interesting observation was that apa2, the second most abundant protein of RJ did not show antibiotic properties ( Figure 3A, apa2), while the antibiotic activity of its minority homologue, apa2a (apa2a) was significant ( Figure 3B, 5). Apa2a showed in SDS-PAGE a single band of Mw of 48 kDa, which was confirmed by MALDI-TOF-MS (7). The immunochemical analysis confirmed that apa2a is immunoactive to anti-apa2 antibody but Edman sequencing showed that N-terminus of apa2a differed to apa2.…”

Assessment of the floral origin of honey via proteomic tools

“…Due to its unique valence as health food for humans (as well as its use in health-promoting medical products and cosmetics), the RJ has been the subject of extensive scientific investigations. In the last few years, these studies have been extended to cover its proteome and indeed some selected publications here listed deal with the establishment of the complete RJ proteome [16][17][18][19][20][21]. Perhaps the most extensive report so far is the one of Furusawa et al [19], who have been able to describe a grand total of 52 unique gene products, of which eight belong to the family of the major royal jelly proteins, which are also the most abundant species visible in both SDS-PAGE as well as 2D maps.…”

Hemolymph proteome changes during worker brood development match the biological divergences between western honey bees (Apis mellifera) and eastern honey bees (Apis cerana)

“…Noticeably, the fact that we identified more hemolymph protein spots of MRJP1 in Acc than in Aml may reflect the different PTM status of this protein in the hemolymph of the two bees. It has been reported the glycosylated MRJP2 can effectively inhibit P. larvae infection [35]. Thus it is believed that different bee species may have different adaptive mechanisms of protein modification to meet the nutritional and immune demands for their own larvae.…”