Galactans biosynthesis

I. A. Hemmingson and R. H. Fumeaux, Manipulation of galactan biosynthesis in Gracilaria chilensis Bird, McLachlan et Oliveira by light deprivation, Bot. Mar., 43 (2000) 285-289. 

KremerL, Dover LG, Morehouse C, Hitchin P, Everett M, Morris HR, Dell A, Brennan PJ, McNeil MR, Flaherty C, Duncan K, Besra GS. Galactan biosynthesis in mycobacterium tuberculosis. Identification of a bifunctional UDP-galactofuransoyltransferase. J. Biol. Chem. 2001 276 26430-26440. 

S.B.E. Hector, Molecular studies of galactan biosynthesis in red algae, PhD thesis. University of Stellenbosch, South Africa, 2013. 

The biosynthesis of other O-specific polysaccharides has still not been investigated. The only additional example of demonstration of such a process is in the formation of (l->3)-a-D-galactan, the Ol antigen of Klebsiella.333 UDP-Gal was identified as the glycosyl donor in the reaction, but further details of the mechanism remain unclear. 

The biosynthesis of such a molecule is theoretically likely to be simple, with the possible exception of the construction of the (unknown) primer. Assembly of the core, which in several peeled galactans has a molecular weight of about 2 X 10 daltons, would require only one galactosyltransferase, while branching would need two arabinosyltransferases to generate LArafl,3Gall- and LArafl,5 Aral-. 

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