title: New Family of Ulvan Lyases Identified in Three Isolates from the Alteromonadales Order.
abstract: Ulvan is the main polysaccharide component of the Ulvales (green seaweed) cell wall. It is composed of disaccharide building blocks comprising 3-sulfated rhamnose linked to d-glucuronic acid (GlcUA), l-iduronic acid (IdoUA), or d-xylose (Xyl). The degradation of ulvan requires ulvan lyase, which catalyzes the endolytic cleavage of the glycoside bond between 3-sulfated rhamnose and uronic acid according to a β-elimination mechanism. The first characterized ulvan lyase was identified in Nonlabens ulvanivorans, an ulvanolytic bacterial isolate. In the current study, we have identified and biochemically characterized novel ulvan lyases from three Alteromonadales isolated bacteria. Two homologous ulvan lyases (long and short) were found in each of the bacterial genomes. The protein sequences have no homology to the previously reported ulvan lyases and therefore are the first representatives of a new family of polysaccharide lyases. The enzymes were heterologously expressed in Escherichia coli to determine their mode of action. The heterologous expressed enzymes were secreted into the milieu subsequent to their signal sequence cleavage. An endolytic mode of action was observed and studied using gel permeation chromatography and (1)H NMR. In contrast to N. ulvanivorans ulvan lyase, cleavage occurred specifically at the GlcUA residues. In light of the genomic context and modular structure of the ulvan lyase families identified to date, we propose that two ulvan degradation pathways evolved independently.
authors.affiliation: From the Institute for Nanotechnology and Advanced Materials, The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, 52900 Ramat Gan, Israel and.
authors.forename: Moran
authors.initials: M
authors.lastname: Kopel
authors.affiliation: the Centre de efRecherches sur les Macromolécules Végétales (UPR-CNRS 5301), Université Joseph Fourier and Institut de Chimie Moléculaire de Grenoble (ICMG, FR-CNRS 2607), Grenoble cedex 9, France. Electronic address: helbert@cermav.cnrs.fr.
authors.forename: William
authors.initials: W
authors.lastname: Helbert
authors.affiliation: From the Institute for Nanotechnology and Advanced Materials, The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, 52900 Ramat Gan, Israel and.
authors.forename: Yana
authors.initials: Y
authors.lastname: Belnik
authors.affiliation: From the Institute for Nanotechnology and Advanced Materials, The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, 52900 Ramat Gan, Israel and.
authors.forename: Vitaliy
authors.initials: V
authors.lastname: Buravenkov
authors.affiliation: From the Institute for Nanotechnology and Advanced Materials, The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, 52900 Ramat Gan, Israel and.
authors.forename: Asael
authors.initials: A
authors.lastname: Herman
authors.affiliation: From the Institute for Nanotechnology and Advanced Materials, The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, 52900 Ramat Gan, Israel and. Electronic address: ehud.banin@biu.ac.il.
authors.forename: Ehud
authors.initials: E
authors.lastname: Banin
mesh_terms: D034241:Alteromonadaceae / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D016680:Genome, Bacterial; D007700:Kinetics; D011133:Polysaccharide-Lyases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011134:Polysaccharides / Q000378:metabolism*; D015854:Up-Regulation
chemical_list: D011134:Polysaccharides; C571831:ulvan; D011133:Polysaccharide-Lyases; C110941:ulvan-lyase
keywords: algae; bacteria; enzyme degradation; glycoside hydrolase; polysaccharide; ulvan