Recent advances on the post-translational modifications of EXTs and their roles in plant cell walls

MELINA VELASQUEZ, JUAN SALGADO SALTER, JAVIER GLOAZZO DOROZS, BENT L. PETERSEN & JOSÉ M. ESTEVEZ

Frontiers in Plant Physiology

Frontiers

Año: 2012 vol. 3 p. 93 - 97

1664-462X

The genetic set up and the enzymes that define the O-glycosylation sites and transfer the activated sugars to cell wall glycoprotein Extensins (EXTs) have remained unknown for a long time. We are now beginning to see the emerging components of the molecular machinery that assembles these complex O-glycoproteins on the plant cell wall. Genes conferring the posttranslational modifications, i.e. proline hydroxylation and subsequent O-glycosylation, of the EXTs have been recently identified. In this review we summarize the enzymes that define the O-glycosylation sites on the O-glycoproteins, i.e. the prolyl 4?hydroxylases (P4Hs), the glycosyltransferases that transfer arabinose units (named arabinosyltransferases, AraTs) and the one responsible for transferring a single galactose (galactosyltransferase GalT) on the protein EXT backbones. We discuss the effects of posttranslational modifications on the structure and function of extensins in plant cell walls.