Expression of the Agrobacterium tumefaciens chvB virulence region in Azospirillum spp

Altabe, Silvia; Iannino, Nora Iñón de; Mendoza, Diego de; Ugalde, Rodolfo A.

doi:10.1128/jb.172.5.2563-2567.1990

Cited by 17 publications

(15 citation statements)

References 25 publications

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“…We recently reported that Azospirillum brasilense does not synthesize cyclic 13(1-2) glucan (1). In this work, we report that A. brasilense synthesizes instead a periplasmic linear 13(1-3),,B(1-6) glucan, the synthesis of which is regulated by the osmotic strength of the growth medium.…”

mentioning

confidence: 63%

“…The A. brasilense CdRif ATCC 29710 strain was used in this study (1). Bacteria were grown in LB broth supplemented with rifampin (100 jig/ml).…”

Section: Materuils and Methodsmentioning

confidence: 99%

“…On the other hand, in medium of high osmotic strength, the synthesis of glucans is strongly repressed in A. tumefaciens (34). In A. tumefaciens, the inhibition of the formation of 1(1-2) glucan at high osmolarity has been shown to be due to an in vivo inhibition of the activity of 1 (1)(2) glucosyltransferase, since inner membranes prepared from cells grown in medium of high or low osmolarity displayed the same specific activity (34).…”

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confidence: 99%

“…In medium of low osmotic strength, R. meliloti andA. tumefaciens mutants defective in the synthesis of ,B (1)(2) glucans are strongly impaired in their ability to grow, suggesting that the glucan is important for survival under such conditions (34). Growth is restored by raising the osmolarity of the medium (34).…”

mentioning

confidence: 99%

“…A cyclic ,B(1-3),,B (1)(2)(3)(4)(5)(6) glucan was isolated from this bacterium (23,28), and the enzymatic synthesis of this compound was studied in vitro (5,14).…”

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confidence: 99%

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New osmoregulated beta(1-3),beta(1-6) glucosyltransferase(s) in Azospirillum brasilense

Altabe¹,

Iannino²,

Mendoza³

et al. 1994

J Bacteriol

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A linear 0(1-3),P(1-6) glucan was detected in the periplasm of Azospirillum brasilense cells growing in a medium of low osmotic strength. This glucan was produced in vitro by purified bacterial inner membranes with UDP-glucose as the sugar donor in the presence of Mg2e. Growth in a high-osmotic-strength medium strongly reduced the amount of this glucan accumulated in the periplasmic space, and the inhibition was associated with a reduction in the enzymatic activity of the P(1-3),0(1-6) glucosyltransferase(s).Bacteria of the genus Azospirillum have been studied extensively because of their effect in promoting plant growth (21). Under certain conditions, they show moderate host specificity, as reflected by their isolation from a wide variety of, but not all, plants. The ability of azospirilla to colonize the rhizosphere, although not fully understood, is presumed to depend on chemotaxis towards root exudates and several other properties determined by bacterial cell surface polysaccharides (10,21,25).In Rhizobium meliloti, the role of exopolysaccharides in nodule development has been well established, and the genes necessary for their production (exo genes) have been identified and studied (2,18,20). Cyclic 1(1-2) glucans play a key role in plant interaction in most species of the family Rhizobiaceae. The chromosomal regions chvB and chvA in Agrobacterium spp. and ndvB and ndvA in Rhizobium spp. are required for the synthesis and secretion of cyclic 1B(1-2) glucan (9,13,30,36).Mutants of R. meliloti and Agrobacterium tumefaciens deficient in the production of cyclic ,B(1-2) glucan form ineffective empty nodules (12) or are avirulent (27, 36), respectively.It has been shown that cellular cyclic P(1-2) glucan production in some members of the family Rhizobiaceae is osmoregulated (24, 34). In medium of low osmotic strength, R. meliloti andA. tumefaciens mutants defective in the synthesis of ,B(1-2) glucans are strongly impaired in their ability to grow, suggesting that the glucan is important for survival under such conditions (34). Growth is restored by raising the osmolarity of the medium (34). On the other hand, in medium of high osmotic strength, the synthesis of glucans is strongly repressed in A. tumefaciens (34). In A. tumefaciens, the inhibition of the formation of 1(1-2) glucan at high osmolarity has been shown to be due to an in vivo inhibition of the activity of 1 (1-2) glucosyltransferase, since inner membranes prepared from cells grown in medium of high or low osmolarity displayed the same specific activity (34).Bradyrhizobium japonicum, a soybean-nodulating bacterium, does not produce 1(1-2) glucan (14 enzymatic synthesis of this compound was studied in vitro (5, 14).We recently reported that Azospirillum brasilense does not synthesize cyclic 13(1-2) glucan (1). In this work, we report that A. brasilense synthesizes instead a periplasmic linear 13(1-3),,B(1-6) glucan, the synthesis of which is regulated by the osmotic strength of the growth medium. MATERUILS AND METHODSBacterial strains and media. The A....

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mentioning

confidence: 63%

“…The A. brasilense CdRif ATCC 29710 strain was used in this study (1). Bacteria were grown in LB broth supplemented with rifampin (100 jig/ml).…”

Section: Materuils and Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

“…A cyclic ,B(1-3),,B (1)(2)(3)(4)(5)(6) glucan was isolated from this bacterium (23,28), and the enzymatic synthesis of this compound was studied in vitro (5,14).…”

mentioning

confidence: 99%

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