Molecular characterization of tomato α1,3/4-fucosidase, a member of glycosyl hydrolase family 29 involved in the degradation of plant complex type N-glycans.

In this study, we identified a gene in tomato that encodes an acidic α-fucosidase (LOC101254568 or Solyc03g006980, α-Fuc'ase S1-1), which may be involved in the turnover of plant complex-type N-glycans. Recombinant α-Fuc'ase S1-1 (rFuc'ase S1-1) was expressed using a baculovirus-insect cell expression system. rFuc'ase Sl-1 is 55 kDa in size and has an optimum pH around 4.5. It substantially hydrolyzed the non-reducing terminal α1,3-fucose residue on LNFP III and α1,4-fucose residues of Lea epitopes on plant complex-type N-glycans, but not the α1,2-fucose residue on LNFP I or the α1,3-fucose residue on pyridylaminated Fucα1-3GlcNAc. Furthermore, we found that this tomato α-Fuc'ase S1-1 was inactive toward the core penta-oligosaccharide unit [Manß1-4(Xylß1-2)GlcNAcß1-4(Fucα1-3)GlcNAc-PA] of plant complex-type N-glycans. Molecular 3D modelling of α-Fuc'ase Sl-1 and structure/sequence interpretation based on comparison with a homologous α-fucosidase from Bifidobacterium longum subsp. infantis (Blon_2336) indicated that residues Asp193 and Glu237 might be important for substrate binding.

Multiple reassortment events among highly pathogenic avian influenza A(H5N1) viruses detected in Bangladesh.

In Bangladesh, little is known about the genomic composition and antigenicity of highly pathogenic avian influenza A(H5N1) viruses, their geographic distribution, temporal patterns, or gene flow within the avian host population. Forty highly pathogenic avian influenza A(H5N1) viruses isolated from humans and poultry in Bangladesh between 2008 and 2012 were analyzed by full genome sequencing and antigenic characterization. The analysis included viruses collected from avian hosts and environmental sampling in live bird markets, backyard poultry flocks, outbreak investigations in wild birds or poultry and from three human cases. Phylogenetic analysis indicated that the ancestors of these viruses reassorted (1) with other gene lineages of the same clade, (2) between different clades and (3) with low pathogenicity avian influenza A virus subtypes. Bayesian estimates of the time of most recent common ancestry, combined with geographic information, provided evidence of probable routes and timelines of virus spread into and out of Bangladesh.