Regulation of urease activity in Rhizobium meliloti

Miksch, Gerhard

doi:10.1016/0378-1097(94)00192-8

Cited by 6 publications

(6 citation statements)

References 8 publications

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“…Obviously, S. pasteurii cultivated with urea showed faster growth and urease production than that without urea, though its maximal urease activity was much lower. This finding was consistent with previous studies that revealed the urease synthesis was repressed in the presence of ammonia in Klebsiella aerogenes, Bacillus subtilis and Rhizobium meliloti [23][24][25]. TSB itself did not produce ammonium, while the addition of urea can generate a high level of ammonium ( Fig.…”

Section: The Effect Of Urea In Culture Medium On S Pasteuriisupporting

confidence: 93%

Beneficial factors for biomineralization by ureolytic bacterium Sporosarcina pasteurii

Pang

Luo

et al. 2020

Microb Cell Fact

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Background: The ureolytic bacterium Sporosarcina pasteurii is well-known for its capability of microbially induced calcite precipitation (MICP), representing a great potential in constructional engineering and material applications. However, the molecular mechanism for its biomineralization remains unresolved, as few studies were carried out. Results: The addition of urea into the culture medium provided an alkaline environment that is suitable for S. pasteurii. As compared to S. pasteurii cultivated without urea, S. pasteurii grown with urea showed faster growth and urease production, better shape, more negative surface charge and higher biomineralization ability. To survive the unfavorable growth environment due to the absence of urea, S. pasteurii up-regulated the expression of genes involved in urease production, ATPase synthesis and flagella, possibly occupying resources that can be deployed for MICP. As compared to non-mineralizing bacteria, S. pasteurii exhibited more negative cell surface charge for binding calcium ions and more robust cell structure as nucleation sites. During MICP process, the genes for ATPase synthesis in S. pasteurii was up-regulated while genes for urease production were unchanged. Interestingly, genes involved in flagella were down-regulated during MICP, which might lead to poor mobility of S. pasteurii. Meanwhile, genes in fatty acid degradation pathway were inhibited to maintain the intact cell structure found in calcite precipitation. Both weak mobility and intact cell structure are advantageous for S. pasteurii to serve as nucleation sites during MICP. Conclusions: Four factors are demonstrated to benefit the super performance of S. pasteurii in MICP. First, the good correlation of biomass growth and urease production of S. pasteurii provides sufficient biomass and urease simultaneously for improved biomineralization. Second, the highly negative cell surface charge of S. pasteurii is good for binding calcium ions. Third, the robust cell structure and fourth, the weak mobility, are key for S. pasteurii to be nucleation sites during MICP.

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Section: The Effect Of Urea In Culture Medium On S Pasteuriisupporting

confidence: 93%

Beneficial factors for biomineralization by ureolytic bacterium Sporosarcina pasteurii

Pang

Luo

et al. 2020

Microb Cell Fact

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“…Urease activity was determined using 100 mL of enzyme extract in 100 mL 0.1 M Tris-maleate buffer containing 1 mM EDTA (pH 7.0) and 50 mM urea, according to Miksch and Eberhardt (1994). Samples were incubated for 30 min at 37°C, and NH 3 concentration was determined spectrophotometrically by modification of the Berthelot reaction (Willis et al, 1993;Yang et al, 1998).…”

Section: Enzyme Assaysmentioning

confidence: 99%

Enzymatic Evidence for the Key Role of Arginine in Nitrogen Translocation by Arbuscular Mycorrhizal Fungi

et al. 2006

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Key enzymes of the urea cycle and 15 N-labeling patterns of arginine (Arg) were measured to elucidate the involvement of Arg in nitrogen translocation by arbuscular mycorrhizal (AM) fungi. Mycorrhiza was established between transformed carrot (Daucus carota) roots and Glomus intraradices in two-compartment petri dishes and three ammonium levels were supplied to the compartment containing the extraradical mycelium (ERM), but no roots. Time courses of specific enzyme activity were obtained for glutamine synthetase, argininosuccinate synthetase, arginase, and urease in the ERM and AM roots.15 NH 4 1 was used to follow the dynamics of nitrogen incorporation into and turnover of Arg. Both the absence of external nitrogen and the presence of L-norvaline, an inhibitor of Arg synthesis, prevented the synthesis of Arg in the ERM and resulted in decreased activity of arginase and urease in the AM root. The catabolic activity of the urea cycle in the roots therefore depends on Arg translocation from the ERM.15 N labeling of Arg in the ERM was very fast and analysis of its time course and isotopomer pattern allowed estimation of the translocation rate of Arg along the mycelium as 0.13 mg Arg mg 21 fresh weight h 21 . The results highlight the synchronization of the spatially separated reactions involved in the anabolic and catabolic arms of the urea cycle. This synchronization is a prerequisite for Arg to be a key component in nitrogen translocation in the AM mycelium.

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“…Nitrogen-limited growth causes high-level expression of urease in Bacillus subtilis, Pseudomonas aeruginosa, Rhizobium meliloti, Klebsiella aerogenes, and Klebsiella pneumoniae (1,8,18,22,23). In K. aerogenes and K. pneumoniae, urease expression is activated during nitrogen-restricted growth by the Ntr regulatory cascade (8,18,28).…”

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confidence: 99%

Expression of the Bacillus subtilis ureABC operon is controlled by multiple regulatory factors including CodY, GlnR, TnrA, and Spo0H

1997

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Microbial ureases are multisubunit metalloenzymes that hydrolyze urea to form carbonic acid and two molecules of ammonia (24). The carbonic acid then dissociates, and the ammonia molecules protonate to form ammonium, causing the pH to increase. Thus, the degradation of urea provides ammonium for incorporation into intracellular metabolites and facilitates survival in acidic environments (7,24). The structural genes encoding both the urease subunits, ureA, ureB, and ureC, and the accessory proteins required for assembly of the urease nickel metallocenter are typically clustered at a single locus (24).

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Regulation of urease activity in Rhizobium meliloti

Cited by 6 publications

References 8 publications

Beneficial factors for biomineralization by ureolytic bacterium Sporosarcina pasteurii

Beneficial factors for biomineralization by ureolytic bacterium Sporosarcina pasteurii

Enzymatic Evidence for the Key Role of Arginine in Nitrogen Translocation by Arbuscular Mycorrhizal Fungi

Expression of the Bacillus subtilis ureABC operon is controlled by multiple regulatory factors including CodY, GlnR, TnrA, and Spo0H

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