title: Maize root lectins mediate the interaction with Herbaspirillum seropedicae via N-acetyl glucosamine residues of lipopolysaccharides.
abstract: Herbaspirillum seropedicae is a plant growth-promoting diazotrophic betaproteobacterium which associates with important crops, such as maize, wheat, rice and sugar-cane. We have previously reported that intact lipopolysaccharide (LPS) is required for H. seropedicae attachment and endophytic colonization of maize roots. In this study, we present evidence that the LPS biosynthesis gene waaL (codes for the O-antigen ligase) is induced during rhizosphere colonization by H. seropedicae. Furthermore a waaL mutant strain lacking the O-antigen portion of the LPS is severely impaired in colonization. Since N-acetyl glucosamine inhibits H. seropedicae attachment to maize roots, lectin-like proteins from maize roots (MRLs) were isolated and mass spectrometry (MS) analysis showed that MRL-1 and MRL-2 correspond to maize proteins with a jacalin-like lectin domain, while MRL-3 contains a B-chain lectin domain. These proteins showed agglutination activity against wild type H. seropedicae, but failed to agglutinate the waaL mutant strain. The agglutination reaction was severely diminished in the presence of N-acetyl glucosamine. Moreover addition of the MRL proteins as competitors in H. seropedicae attachment assays decreased 80-fold the adhesion of the wild type to maize roots. The results suggest that N-acetyl glucosamine residues of the LPS O-antigen bind to maize root lectins, an essential step for efficient bacterial attachment and colonization.
authors.affiliation: Department of Biochemistry and Molecular Biology, Universidade Federal do Paraná, Curitiba, Paraná, Brazil.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Balsanelli
authors.forename: Thalita Regina
authors.initials: TR
authors.lastname: Tuleski
authors.forename: Valter Antonio
authors.initials: VA
authors.lastname: de Baura
authors.forename: Marshall Geoffrey
authors.initials: MG
authors.lastname: Yates
authors.forename: Leda Satie
authors.initials: LS
authors.lastname: Chubatsu
authors.forename: Fabio de Oliveira
authors.initials: Fde O
authors.lastname: Pedrosa
authors.forename: Emanuel Maltempi
authors.initials: EM
authors.lastname: de Souza
authors.forename: Rose Adele
authors.initials: RA
authors.lastname: Monteiro
mesh_terms: D000117:Acetylglucosamine; D001422:Bacterial Adhesion; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D042803:Herbaspirillum / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D054884:Host-Pathogen Interactions; D016296:Mutagenesis; D019081:O Antigens / Q000737:chemistry / Q000378:metabolism*; D037121:Plant Lectins / Q000378:metabolism*; D018517:Plant Roots / Q000378:metabolism / Q000382:microbiology*; D003313:Zea mays / Q000378:metabolism / Q000382:microbiology*
chemical_list: D001426:Bacterial Proteins; D019081:O Antigens; D037121:Plant Lectins; D000117:Acetylglucosamine