Biochemical characterization of avirulent exoC mutants of Agrobacterium tumefaciens

The synthesis of periplasmic β(1-2)glucan is required for crown gall tumor formation by Agrobacterium tumefaciens and for effective nodulation of alfalfa by Rhizobium meliloti. The exoC (pscA) gene is required for this synthesis by both bacteria as well as for the synthesis of capsular polysaccharid...

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Autores principales: Uttaro, A.D., Cangelosi, G.A., Geremia, R.A., Nester, E.W., Ugalde, R.A.
Formato: JOUR
Materias:
glucan
phosphoglucomutase
polysaccharide
article
biosynthesis
defective mutant
nonhuman
priority journal
Rhizobium radiobacter
Agrobacterium tumefaciens
Medicago sativa
Rhizobium
Sinorhizobium meliloti
Acceso en línea:http://hdl.handle.net/20.500.12110/paper_00219193_v172_n3_p1640_Uttaro
Aporte de:
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
id todo:paper_00219193_v172_n3_p1640_Uttaro
record_format dspace
spelling todo:paper_00219193_v172_n3_p1640_Uttaro2023-10-03T14:22:46Z Biochemical characterization of avirulent exoC mutants of Agrobacterium tumefaciens Uttaro, A.D. Cangelosi, G.A. Geremia, R.A. Nester, E.W. Ugalde, R.A. glucan phosphoglucomutase polysaccharide article biosynthesis defective mutant nonhuman priority journal Rhizobium radiobacter Agrobacterium tumefaciens Medicago sativa Rhizobium Sinorhizobium meliloti The synthesis of periplasmic β(1-2)glucan is required for crown gall tumor formation by Agrobacterium tumefaciens and for effective nodulation of alfalfa by Rhizobium meliloti. The exoC (pscA) gene is required for this synthesis by both bacteria as well as for the synthesis of capsular polysaccharide and normal lipopolysaccharide. We tested the possibility that the pleiotropic ExoC phenotype is due to a defect in the synthesis of an intermediate common to several polysaccharide biosynthetic pathways. Cytoplasmic extracts from wild-type A. tumefaciens and from exoC mutants of A. tumefaciens containing a cloned wild-type exoC gene synthesized in vitro UDP-glucose from glucose, glucose 1-phosphate, and glucose 6-phosphate. Extracts from exoC mutants synthesized UDP-glucose from glucose 1-phosphate but not from glucose or glucose 6-phosphate. Membranes from exoC mutant cells synthesized β(1-2)glucan in vitro when exogenous UDP-glucose was added and contained the 235-kilodalton protein, which has been shown to carry out this synthesis in wild-type cells. We conclude that the inability of exoC mutants to synthesize β(1-2)glucan is due to a deficiency in the activity of the enzyme phosphoglucomutase (EC 2.7.5.1), which in wild-type bacteria converts glucose 6-phosphate to glucose 1-phosphate, an intermediate in the synthesis of UDP-glucose. This interpretation can account for all of the deficiencies in polysaccharide synthesis which have been observed in these mutants. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_00219193_v172_n3_p1640_Uttaro
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic glucan
phosphoglucomutase
polysaccharide
article
biosynthesis
defective mutant
nonhuman
priority journal
Rhizobium radiobacter
Agrobacterium tumefaciens
Medicago sativa
Rhizobium
Sinorhizobium meliloti
spellingShingle glucan
phosphoglucomutase
polysaccharide
article
biosynthesis
defective mutant
nonhuman
priority journal
Rhizobium radiobacter
Agrobacterium tumefaciens
Medicago sativa
Rhizobium
Sinorhizobium meliloti
Uttaro, A.D.
Cangelosi, G.A.
Geremia, R.A.
Nester, E.W.
Ugalde, R.A.
Biochemical characterization of avirulent exoC mutants of Agrobacterium tumefaciens
topic_facet glucan
phosphoglucomutase
polysaccharide
article
biosynthesis
defective mutant
nonhuman
priority journal
Rhizobium radiobacter
Agrobacterium tumefaciens
Medicago sativa
Rhizobium
Sinorhizobium meliloti
description The synthesis of periplasmic β(1-2)glucan is required for crown gall tumor formation by Agrobacterium tumefaciens and for effective nodulation of alfalfa by Rhizobium meliloti. The exoC (pscA) gene is required for this synthesis by both bacteria as well as for the synthesis of capsular polysaccharide and normal lipopolysaccharide. We tested the possibility that the pleiotropic ExoC phenotype is due to a defect in the synthesis of an intermediate common to several polysaccharide biosynthetic pathways. Cytoplasmic extracts from wild-type A. tumefaciens and from exoC mutants of A. tumefaciens containing a cloned wild-type exoC gene synthesized in vitro UDP-glucose from glucose, glucose 1-phosphate, and glucose 6-phosphate. Extracts from exoC mutants synthesized UDP-glucose from glucose 1-phosphate but not from glucose or glucose 6-phosphate. Membranes from exoC mutant cells synthesized β(1-2)glucan in vitro when exogenous UDP-glucose was added and contained the 235-kilodalton protein, which has been shown to carry out this synthesis in wild-type cells. We conclude that the inability of exoC mutants to synthesize β(1-2)glucan is due to a deficiency in the activity of the enzyme phosphoglucomutase (EC 2.7.5.1), which in wild-type bacteria converts glucose 6-phosphate to glucose 1-phosphate, an intermediate in the synthesis of UDP-glucose. This interpretation can account for all of the deficiencies in polysaccharide synthesis which have been observed in these mutants.
format JOUR
author Uttaro, A.D.
Cangelosi, G.A.
Geremia, R.A.
Nester, E.W.
Ugalde, R.A.
author_facet Uttaro, A.D.
Cangelosi, G.A.
Geremia, R.A.
Nester, E.W.
Ugalde, R.A.
author_sort Uttaro, A.D.
title Biochemical characterization of avirulent exoC mutants of Agrobacterium tumefaciens
title_short Biochemical characterization of avirulent exoC mutants of Agrobacterium tumefaciens
title_full Biochemical characterization of avirulent exoC mutants of Agrobacterium tumefaciens
title_fullStr Biochemical characterization of avirulent exoC mutants of Agrobacterium tumefaciens
title_full_unstemmed Biochemical characterization of avirulent exoC mutants of Agrobacterium tumefaciens
title_sort biochemical characterization of avirulent exoc mutants of agrobacterium tumefaciens
url http://hdl.handle.net/20.500.12110/paper_00219193_v172_n3_p1640_Uttaro
work_keys_str_mv AT uttaroad biochemicalcharacterizationofavirulentexocmutantsofagrobacteriumtumefaciens
AT cangelosiga biochemicalcharacterizationofavirulentexocmutantsofagrobacteriumtumefaciens
AT geremiara biochemicalcharacterizationofavirulentexocmutantsofagrobacteriumtumefaciens
AT nesterew biochemicalcharacterizationofavirulentexocmutantsofagrobacteriumtumefaciens
AT ugaldera biochemicalcharacterizationofavirulentexocmutantsofagrobacteriumtumefaciens
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