This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The C. elegans cuticle is infected by the nematode bacterial pathogen Microbacterium nematophilum. In screens for C. elegans mutants with altered susceptibility to infection, several bus (bacteria unswollen) mutants were isolated and exhibited increased resistance to infection. DNA sequencing experiments and homology searches suggest strongly that glycoconjugate biosynthetic enzymes may be disrupted in these mutants. The srf-3 mutants contain genetic lesions in a Golgi nucleotide sugar transporter and are also resistant to M. nematophilum infection, supporting the notion that the bus phenotype is due to a loss of function in one or more glycoconjugate pathways. We are carrying out analysis of the glycoconjugates of the several bus mutants. Since homology does not necessarily accurately predict function, we are investigating several glycoconjugate classes in tandem. We are performing mass spectrometric analysis of N- and O-glycans and glycosphingolipids of the mutants and are comparing the results for these to the corresponding glycans of the wild-type C. elegans N2 bristol strain using methods we have developed and adapted to the C. elegans model. We have observed that the mutants have a series of higher-mass O-glycans that contain glucuronic acid as an internal residue and represent a novel family of glycans. The structures of these nnovel compounds have been determined and the manuscript describing the results has been accepted for publication in the Jounal of Biological Chemistry (E Palaima et al., The caenorhabditis elegans bus-2 mutant reveals a new class of O-glycansaffecting bacterial resistance.J Biol Chem. 2010 Apr 12;[Epub ahead of print] ).