Multiple species of cellular slime mold (CSM) amoebae share overlapping subterranean environments near the soil surface. Despite similar life-styles, individual species form independent starvation-induced fruiting bodies whose spores can renew the life cycle. N-glycans associated with the cell surface glycocalyx have been predicted to contribute to interspecific avoidance, resistance to pathogens, and prey preference. N-glycans from five CSM species that diverged 300-600 million years ago and whose genomes have been sequenced were fractionated into neutral and acidic pools and profiled by MALDI-TOF-MS. Glycan structure models were refined using linkage specific antibodies, exoglycosidase digestions, MALDI-MS/MS, and chromatographic studies. Amoebae of the type species Dictyostelium discoideum express modestly trimmed high mannose N-glycans variably modified with core α3-linked Fuc and peripherally decorated with 0-2 residues each of β-GlcNAc, Fuc, methylphosphate and/or sulfate, as reported previously. Comparative analyses of D. purpureum, D. fasciculatum, Polysphondylium pallidum, and Actyostelium subglobosum revealed that each displays a distinctive spectrum of high-mannose species with quantitative variations in the extent of these modifications, and qualitative differences including retention of Glc, mannose methylation, and absence of a peripheral GlcNAc, fucosylation, or sulfation. Starvation-induced development modifies the pattern in all species but, except for universally observed increased mannose-trimming, the N-glycans do not converge to a common profile. Correlations with glycogene repertoires will enable future reverse genetic studies to eliminate N-glycomic differences to test their functions in interspecific relations and pathogen evasion.
evolution, N-glycan, Dictyostelium, Cellular slime molds, Social amoebae
NCBI PubMed ID: 25987342Publication DOI: 10.1007/s10719-015-9592-8Journal NLM ID: 8603310Publisher: Kluwer Academic Publishers
Correspondence: Christopher M. West
; Christopher M. West
Institutions: Department of Biochemistry & Molecular Biology, Oklahoma Center for Medical Glycobiology, University of Oklahoma Health Sciences Center, 975 NE 10th St., BRC-415, OUHSC, Oklahoma City, OK, 73104, USA
Methods: SDS-PAGE, Western blotting, MALDI-TOF MS, enzymatic digestion, permethylation, CC, MALDI-TOF/TOF MS, bioinformatic analysis (BLASTp)
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