Complex posttranlational modifications in EXT proteins that control root hair tip-growth in Arabidopsis

VELÁSQUEZ SM. ; ELIANA MARZOL; MANGANO S; ESTEVEZ JM

Congreso; 23rd Congress of the International Union of Biochemistry and Molecular Biology (IUBMB) and 44th Annual Meeting of the Brazilian Society for Biochemistry and Molecular Biology ? SBBq; 2014

Root hairs are single cells, responsible for the absorption of water and nutrients in the plant. Their cell walls are composed of polysaccharidesand hydroxyproline (Hyp)-rich glycoproteins that include collagen-like extensins (EXTs) proteins that unlike collagen are highlyO-glycosylated. Through previous work we had demonstrated that O-glycosylation on EXTs is essential for cell-wall self-assembly and,hence, root hair elongation. We successfully determined several players involved in this process that consists of sequential steps ofpost-translational modifications (PMTs): proline hydroxilation and Hyp-O-arabinosylation. We identified 3 prolyl-4-hydroxilases (P4H2, 5and 13) out of the 13 present in Arabidopsis thaliana, 2 arabinosyltransferases (XEG113-2 and RRA3) and several EXTs in the processof root hair growth. In our current study we address the physiological significance of these PMTs present in EXTs together with the characterizationof the enzymes involved.