Biochemical and Functional Characterization of Transiently Expressed in Neural Precursor (TENP) Protein in Emu Egg White

Abstract

A protein transiently expressed in the neural precursors of developing tissues (TENP) was found to be present in emu (Dromaius novaehollandiae) egg white as one of the major proteins. Nucleotide analysis of its encoding cDNA revealed a sequence of 452 amino acids including a 19 amino acid peptide signal. Phylogenetic analysis determined that emu TENP was clustered within the bactericidal/permeability-increasing protein (BPI) superfamily together with other avian TENPs. RT-PCR analysis revealed that the emu TENP gene was highly expressed in the magnum of the oviduct, indicating that TENP is a major egg white component. Emu TENP was purified by anion exchange chromatography and ammonium sulfate fractionation. Unlike BPI, emu TENP exhibited antibacterial activity against Gram-positive bacteria, including Micrococcus luteus and Bacillus subtilis, but not against Gram-negative bacteria such as Escherichia coli and Salmonella Typhimurium. The results suggest that emu TENP is a potent novel antibacterial protein with a spectrum distinct from that of BPI.

Proteomic analysis of egg white heparin-binding proteins: towards the identification of natural antibacterial molecules

“…Their presence in the fraction bound to heparin is likely to be fortuitous. Interestingly enough, the antibacterial activity of six of the proteins of this list or their mammalian counterpart have already been reported to be antibacterial: AvBD11 16 , OVAX 17 , lysozyme 18 , ovotransferrin 19 , avidin 20 , pleiotrophin 5 , and TENP 21 , which validates the initial strategy. An antibacterial activity against Listeria monocytogenes was observed in the diluted raw egg white and in both heparin-unbound and heparin-bound fractions to heparin, at 500 μg/mL ( Fig.…”

“…Protein TENP (Transiently Expressed in Neural Precursor) is a protein possessing strong homology with members of the bactericidal/permeability increasing protein family (BPI) 34 . In emu egg, protein TENP is a protein of high abundance (it accounts for about 16% of total proteins in emu egg white) whereas it is relatively low concentrated in chicken egg white (0.1−0.5% of chicken egg white total protein content) 21 35 . Protein TENP in emu was shown to exhibit antibacterial activity against Gram-positive bacteria 21 .…”

“…In emu egg, protein TENP is a protein of high abundance (it accounts for about 16% of total proteins in emu egg white) whereas it is relatively low concentrated in chicken egg white (0.1−0.5% of chicken egg white total protein content) 21 35 . Protein TENP in emu was shown to exhibit antibacterial activity against Gram-positive bacteria 21 . Considering the high sequence identity between emu and chicken forms (58%), chicken protein TENP is expected to be an antibacterial agent.…”

The calcified eggshell matrix proteome of a songbird, the zebra finch (Taeniopygia guttata)

“…Tenp (Transiently expressed in neural precursors) was first detected in the developing retina and brain of chicken embryos [ 97 ]. It was then shown to occur in chicken egg white in the first proteomic study of egg white [ 98 ] and more recently in emu egg white [ 99 ]. It was also identified in chicken egg yolk [ 100 ] and vitelline membrane [ 101 ].…”

“…The eggshell matrices of chicken [ 30 ] and turkey [ 52 ], but not that of quail [ 53 ], contained small amounts of Tenp. The presence of a bactericidal/permeability increasing domain (BPI) in the sequence of Tenp identifies it as a member of the BPI-like family of innate immune proteins and its antimicrobial activity was confirmed recently [ 99 ].…”