Putative β-1-2-arabinosyltransferases in Chlamydomonas

Philipp Kaiserand Sabine Waffenschmidt

Institute of Biochemistry, University of Cologne, D-50674 Cologne, Germany

Recently we found that Hydroxyproline-rich glycoproteins (HRGPs) in Chlamydomonas are posttranslationally modified with sugar side chains which all start with a β-1-2-arabinose-β-1-2-arabinose core element linked to hydroxyproline. As Chlamydomonas HRGPs share this core with the extensins of higher plants, we hypothesized that the genome of Chlamydomonas and higher plants share two homologous arabinosyltransferases, which are involved in this posttranslational modification and are unknown so far. In a bioinformatics approach using the data set of genes that are exclusively in Chlamydomonas and plants but not in animal genomes (kindly provided by Susan Dutcher) and two putative sequences of arabinosyl-ransferases provided by Peter Ulkskov, Kopenhagen, we could find three open reading frames that might encode the proteins of interest. All three proteins have a nucleotide-binding site (Rossman fold) and a diagnostic protein motif of glycosyltransferases. The function of these genes is currently studied by RNAi experiments and characterization of the respective mutants.

e-mail address of corresponding author: waff@uni-koeln.de