title: The succinoglycan endoglycanase encoded by exoK is required for efficient symbiosis of Sinorhizobium meliloti 1021 with the host plants Medicago truncatula and Medicago sativa (Alfalfa).
abstract: The acidic polysaccharide succinoglycan produced by the nitrogen-fixing rhizobial symbiont Sinorhizobium meliloti 1021 is required for this bacterium to invade the host plant Medicago truncatula and to efficiently invade the host plant M. sativa (alfalfa). The β-glucanase enzyme encoded by exoK has previously been demonstrated to cleave succinoglycan and participate in producing the low molecular weight form of this polysaccharide. Here, we show that exoK is required for efficient S. meliloti invasion of both M. truncatula and alfalfa. Deletion mutants of exoK have a substantial reduction in symbiotic productivity on both of these plant hosts. Insertion mutants of exoK have an even less productive symbiosis than the deletion mutants with the host M. truncatula that is caused by a secondary effect of the insertion itself, and may be due to a polar effect on the expression of the downstream exoLAMON genes.
authors: Department of Biological Science, Florida State University, Tallahassee, FL 32306-4370, USA.
authors: Hajeewaka C
authors: HC
authors: Mendis
authors: Clothilde
authors: C
authors: Queiroux
authors: Tess E
authors: TE
authors: Brewer
authors: Olivia M
authors: OM
authors: Davis
authors: Brian K
authors: BK
authors: Washburn
authors: Kathryn M
authors: KM
authors: Jones
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D018533:Biomass; D005816:Genetic Complementation Test; D006026:Glycoside Hydrolases / Q000235:genetics* / Q000378:metabolism; D000455:Medicago sativa / Q000382:microbiology*; D046913:Medicago truncatula / Q000382:microbiology*; D009154:Mutation; D009586:Nitrogen Fixation; D010641:Phenotype; D055170:Plant Root Nodulation; D018517:Plant Roots / Q000382:microbiology; D018520:Plant Shoots / Q000382:microbiology; D011135:Polysaccharides, Bacterial / Q000378:metabolism; D011993:Recombinant Fusion Proteins; D016962:Sinorhizobium meliloti / Q000201:enzymology* / Q000235:genetics / Q000502:physiology; D013559:Symbiosis
chemical_list: D001426:Bacterial Proteins; D011135:Polysaccharides, Bacterial; D011993:Recombinant Fusion Proteins; C056779:succinoglycan; D006026:Glycoside Hydrolases; C020668:glycanase