title: A novel cyclic beta-1,2-glucan mutant of Rhizobium meliloti.
abstract: The periplasmic cyclic beta-1,2-glucans produced by bacteria within the Rhizobiaceae family provide functions during hypo-osmotic adaptation and plant infection. In Rhizobium meliloti, these molecules are highly modified with phosphoglycerol and succinyl substituents, and it is possible that the anionic character of these glucans is important for their functions. In the present study, we have used a thin-layer chromatographic screening method to identify a novel R. meliloti mutant specifically blocked in its ability to transfer phosphoglycerol substituents to the cyclic beta-1,2-glucan backbone. Further analysis revealed that the cyclic glucans produced by this mutant contained elevated levels of succinyl substituents. As a result, the overall anionic charge on the cyclic beta-1,2-glucans was found to be similar to that of wild-type cells. Despite this difference in cyclic beta-1,2-glucan structure, the mutant was shown to effectively nodulate alfalfa and to grow as well as wild-type cells in hypo-osmotic media.
authors.affiliation: Department of Food Science, Pennsylvania State University, University Park 16802, USA.
authors.forename: M W
authors.initials: MW
authors.lastname: Breedveld
authors.forename: J A
authors.initials: JA
authors.lastname: Hadley
authors.forename: K J
authors.initials: KJ
authors.lastname: Miller
mesh_terms: D001483:Base Sequence; D002462:Cell Membrane / Q000378:metabolism; D002473:Cell Wall / Q000378:metabolism; D019852:Diacylglycerol Kinase; D005936:Glucans / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism; D005947:Glucose / Q000032:analysis; D007038:Hypotonic Solutions; D000455:Medicago sativa / Q000382:microbiology; D008969:Molecular Sequence Data; D009154:Mutation; D010710:Phosphates / Q000032:analysis; D010715:Phosphatidylglycerols / Q000032:analysis; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism; D016962:Sinorhizobium meliloti / Q000737:chemistry* / Q000201:enzymology / Q000235:genetics / Q000254:growth & development; D013386:Succinates / Q000032:analysis; D047071:beta-Glucans
chemical_list: D005936:Glucans; D007038:Hypotonic Solutions; D010710:Phosphates; D010715:Phosphatidylglycerols; D013386:Succinates; D047071:beta-Glucans; C033744:beta-1,2-glucan; D017853:Phosphotransferases (Alcohol Group Acceptor); D019852:Diacylglycerol Kinase; D005947:Glucose