Article

The structure of Cryptococcus neoformans galactoxylomannan contains beta-D-glucuronic acid

Analytical Services/Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, GA 30602, USA.
Carbohydrate research (Impact Factor: 1.92). 04/2009; 344(7):915-20. DOI: 10.1016/j.carres.2009.03.003
Source: PubMed

ABSTRACT The structure of galactoxylomannan, a capsular polysaccharide from the opportunistic yeast Cryptococcus neoformans, was re-examined by NMR spectroscopy and GC-MS. The residue that is 3-linked to the side chain galactose and was previously assigned as beta-D-xylose [Vaishnav, V. V.; Bacon, B. E.; O'Neill, M.; Cherniak, R. Carbohydr. Res.1998, 306, 315-330] was determined to be beta-D-glucuronic acid. A revised structure for this polymer is presented, along with a proposal that this compound be termed glucuronoxylomannogalactan (GXMGal).

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Available from: Tamara Doering, Aug 15, 2015
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    • "Cryptococcal PS can be secreted via the protein secretory pathway ( Yoneda and Doering , 2006 ; Panepinto et al. , 2009 ) , or shed from cells in association with vesicular structures ( Rodrigues et al . , 2007 ) , and consists of at least two types of polymers : glucuronoxylomannan ( GXM ) and glucuronoxylomannogalactan ( GXMGal ; Heiss et al . , 2009 ) . Despite the homogenous appearance of the capsule by light microscopy , electron microscopy ( EM ) data suggest that the capsule is a heterogeneous structure , with a clear vertical " stratification " of the matrix into an electron - dense inner layer and an electron - lucent outer layer ( Gates et al . , 2004 ; Bryan et al . , 2005 "
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    • "Besides these surface-exposed enzymes, the polysaccharide capsule is considered to be one of the main virulence factors [12]. The capsule consists mainly of the polysaccharides glu curonoxylomannan (GXM) and glucuronoxylomannogalactan (GXMGal) [17] [20], in a mass:ratio of about 10:1 [8]. This capsule enables the yeast-like fungus to survive the harsh environment of the human body by immune evasion and by preventing killing through phagocytosis by macrophages [27] [31]. "
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    • "In C. neoformans and C. gattii, the capsule is mainly composed of the polysaccharides glucuronoxylomannan (GXM) and galactoxylomannan (GalXM; Zaragoza et al., 2009; Rodrigues et al., 2011). An alteration in the GalXM nomenclature to glucuronoxylomannogalactan (GXMGal) has been recently proposed based on structural aspects and monosaccharide composition (Heiss et al., 2009). The principal capsular polysaccharide component in both species is GXM, which consists of a polymer composed of an α1,3 linked mannosyl backbone with β1,2 and β1,4 xylosyl and glucuronyl substitutions (for details, see Zaragoza et al., 2009). "
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