title: A four-gene operon inBacillus cereusproduces two rare spore-decorating sugars.
abstract: Bacterial glycan structures on cell surfaces are critical for cell-cell recognition and adhesion and in host-pathogen interactions. Accordingly, unraveling the sugar composition of bacterial cell surfaces can shed light on bacterial growth and pathogenesis. Here, we found that two rare sugars with a 3-C-methyl-6-deoxyhexose structure were linked to spore glycans inBacillus cereusATCC 14579 and ATCC 10876. Moreover, we identified a four-gene operon inB. cereusATCC 14579 that encodes proteins with the following sequential enzyme activities as determined by mass spectrometry and one- and two-dimensional NMR methods: CTP:glucose-1-phosphate cytidylyltransferase, CDP-Glc 4,6-dehydratase, NADH-dependent SAM:C-methyltransferase, and NADPH-dependent CDP-3-C-methyl-6-deoxyhexose 4-reductase. The last enzyme predominantly yielded CDP-3-C-methyl-6-deoxygulose (CDP-cereose) and likely generated a 4-epimer CDP-3-C-methyl-6-deoxyallose (CDP-cillose). Some members of theB. cereus sensu latogroup produce CDP-3-C-methyl-6-deoxy sugars for the formation of cereose-containing glycans on spores, whereas others such asBacillus anthracisdo not. Gene knockouts of theBacillus C-methyltransferase and the 4-reductase confirmed their involvement in the formation of cereose-containing glycan onB. cereusspores. We also found that cereose represented 0.2-1% spore dry weight. Moreover, mutants lacking cereose germinated faster than the wild type, yet the mutants exhibited no changes in sporulation or spore resistance to heat. The findings reported here may provide new insights into the roles of the uncommon 3-C-methyl-6-deoxy sugars in cell-surface recognition and host-pathogen interactions of the genusBacillus.
authors.affiliation: From the Complex Carbohydrate Research Center and.|the Department of Plant Biology, University of Georgia, Athens, Georgia 30602.
authors.forename: Zi
authors.initials: Z
authors.lastname: Li
authors.affiliation: From the Complex Carbohydrate Research Center and.
authors.forename: Thiya
authors.initials: T
authors.lastname: Mukherjee
authors.affiliation: From the Complex Carbohydrate Research Center and.
authors.forename: Kyle
authors.initials: K
authors.lastname: Bowler
authors.affiliation: From the Complex Carbohydrate Research Center and.
authors.forename: Sholeh
authors.initials: S
authors.lastname: Namdari
authors.affiliation: From the Complex Carbohydrate Research Center and.
authors.forename: Zachary
authors.initials: Z
authors.lastname: Snow
authors.affiliation: From the Complex Carbohydrate Research Center and.
authors.forename: Sarah
authors.initials: S
authors.lastname: Prestridge
authors.affiliation: From the Complex Carbohydrate Research Center and.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Carlton
authors.affiliation: From the Complex Carbohydrate Research Center and peled@ccrc.uga.edu.|the Department of Plant Biology, University of Georgia, Athens, Georgia 30602.
authors.forename: Maor
authors.initials: M
authors.lastname: Bar-Peled
mesh_terms: D001409:Bacillus cereus / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D055785:Gene Knockdown Techniques; D008780:Methyltransferases / Q000235:genetics / Q000378:metabolism; D009876:Operon / Q000502:physiology*; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism; D011135:Polysaccharides, Bacterial / Q000096:biosynthesis* / Q000235:genetics; D013171:Spores, Bacterial / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D011135:Polysaccharides, Bacterial; D010088:Oxidoreductases; D008780:Methyltransferases
keywords: Bacillus; BclA; carbohydrate biosynthesis; cereose; cillose; germination; glycobiology; glycosylation; spores; sporulation