The cattle tick antigen, Bm95, expressed in Pichia pastoris contains short chains of N- and O-glycans

Bm95 is an antigen isolated from Boophilus microplus strains with low susceptibility to antibodies developed in cattle vaccinated with the recombinant Bm86 antigen (Gavac, HeberBiotec S.A., Cuba). It is a Bm86-like surface protein, which by similarity contains seven EGF-like domains and a lipid-binding GPI-anchor site at the C-terminal region. The primary structure of the recombinant (rBm95) protein expressed in Pichia pastoris was completely verified by LC/MS. The four potential glycosylation sites (Asn 122, 163, 329, and 363) are glycosylated partially with short N-glycans, from Man(5)GlcNAc(2) to Man(9)GlcNAc(2) of which, Man(8-9)GlcNAc(2) were the most abundant. O-Glycopeptides are distributed mostly towards the protein N-terminus. While the first N-glycosylated site (Asn(122)) is located between EGF-like domains 2 and 3, where the O-glycopeptides were found, two other N-glycosylated sites (Asn(329) and Asn(363)) are located between EGF-like domains 5 and 6, a region devoid of O-glycosylated Ser or Thr.

Production and biochemical characterization of the recombinant Boophilus microplus Bm95 antigen from Pichia pastoris

The new antigen Bm95 from the cattle tick Boophilus microplus was recently isolated, cloned and expressed in the methylotrophic yeast Pichia pastoris. The recombinant protein has shown to induce protection in cattle against infestations of B. microplus under controlled and production conditions. In this paper we report the production and large-scale purification of the Bm95 protein, following a simple and cost-effective process. The antigen was obtained highly aggregated, forming particles ranging from 26 to 30 nm and with purity higher than 80%. The process yield was 0.55 g of pure Bm95 protein per liter of culture. The 98% of the primary structure of the recombinant protein was verified by mass spectrometry. Three amino acid changes in comparison with the sequence deduced from cDNA were detected by LC-MS/MS. The antigen was also obtained N-glycosylated, as previously reported for heterologous protein expression in P. pastoris.

Primary structure of two cytolysin isoforms from Stichodactyla helianthus differing in their hemolytic activity

Sticholysin I (St-I) and sticholysin II (St-II) are cytolysins purified from the sea anemone Stichodactyla helianthus with a high degree of sequence identity (93%) but clearly differenced in their hemolytic activity. In order to go further into the structural determinants for the different behavior of St-I and St-II, we report here the complete amino acid sequences and the consensus secondary structure prediction of both proteins. The complete determination of St-II primary structure confirms the partial revision of cytolysin III amino acid sequence. All nonconservative changes between St-I and St-II are located at the N-terminal. According to our prediction these changes could be located at the same face of an alpha-helix during pore formation events and could account for the observed differences in hemolytic activity between St-I and St-II.