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Adaptative biochemical pathways and regulatory networks in Klebsiella oxytoca BAS-10 producing a biotechnologically relevant exopolysaccharide during Fe(III)-citrate fermentation.

Gallo G, Baldi F, Renzone G, Gallo M, Cordaro A, Scaloni A, Puglia AM - Microb. Cell Fact. (2012)

Bottom Line: Unlikely other enterobacteria, BAS-10 is able to grow on Fe(III)-citrate as sole carbon and energy source, yielding acetic acid and CO2 coupled with Fe(III) reduction to Fe(II) and showing unusual physiological characteristics.The protein differential regulation seems to ensure efficient cell growth coupled with EPS production by adapting metabolic and biochemical processes in order to face iron toxicity and to optimize energy production.Differential proteomics provided insights on the molecular mechanisms necessary for anaeorobic utilization of Fe(III)-citrate in a biotechnologically promising enterobacteriun, also revealing genes that can be targeted for the rational design of high-yielding EPS producer strains.

View Article: PubMed Central - HTML - PubMed

Affiliation: Dipartimento di Scienze e Tecnologie Molecolari e Biomolecolari (STEMBIO), Università di Palermo Viale delle Scienze, ed, 16, Parco d'Orleans II, Palermo, 90128, Italy. giumir@msn.com

ABSTRACT

Background: A bacterial strain previously isolated from pyrite mine drainage and named BAS-10 was tentatively identified as Klebsiella oxytoca. Unlikely other enterobacteria, BAS-10 is able to grow on Fe(III)-citrate as sole carbon and energy source, yielding acetic acid and CO2 coupled with Fe(III) reduction to Fe(II) and showing unusual physiological characteristics. In fact, under this growth condition, BAS-10 produces an exopolysaccharide (EPS) having a high rhamnose content and metal-binding properties, whose biotechnological applications were proven as very relevant.

Results: Further phylogenetic analysis, based on 16S rDNA sequence, definitively confirmed that BAS-10 belongs to K. oxytoca species. In order to rationalize the biochemical peculiarities of this unusual enterobacteriun, combined 2D-Differential Gel Electrophoresis (2D-DIGE) analysis and mass spectrometry procedures were used to investigate its proteomic changes: i) under aerobic or anaerobic cultivation with Fe(III)-citrate as sole carbon source; ii) under anaerobic cultivations using Na(I)-citrate or Fe(III)-citrate as sole carbon source. Combining data from these differential studies peculiar levels of outer membrane proteins, key regulatory factors of carbon and nitrogen metabolism and enzymes involved in TCA cycle and sugar biosynthesis or required for citrate fermentation and stress response during anaerobic growth on Fe(III)-citrate were revealed. The protein differential regulation seems to ensure efficient cell growth coupled with EPS production by adapting metabolic and biochemical processes in order to face iron toxicity and to optimize energy production.

Conclusion: Differential proteomics provided insights on the molecular mechanisms necessary for anaeorobic utilization of Fe(III)-citrate in a biotechnologically promising enterobacteriun, also revealing genes that can be targeted for the rational design of high-yielding EPS producer strains.

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Regulatory network controlling the expression or the activity ofK. oxytocaBAS-10 differentially abundant proteins. The relationships are reported according to EcoCyc database [23], Bott (1997) [1], Salmon et al. (2005) [34] and Kumar et al. (2011) [49]. Dashed lines refer to an indirect relationship.
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Figure 5: Regulatory network controlling the expression or the activity ofK. oxytocaBAS-10 differentially abundant proteins. The relationships are reported according to EcoCyc database [23], Bott (1997) [1], Salmon et al. (2005) [34] and Kumar et al. (2011) [49]. Dashed lines refer to an indirect relationship.

Mentions: The proteomic comparison showed down-regulation in anaerobic FEC of EIIAGlc, a component of bacterial phosphoenolpyruvate (PEP): carbohydrate phosphotransferase system (PTS), which was revealed as two protein spots differing for Mw in 2D-maps (Table 1, Figures 2 and 3; Additional file 1 Table S1 and Figure S2). The differential regulation of EIIAGlc may be related to the differential regulation of central carbon metabolism enzymes. In fact, in both Gram-negative and Gram-positive bacteria PTS consists of several factors interacting with different regulatory proteins thus controlling glucose metabolism and many other cellular functions [33]. In particular, EIIAGlc is the central processing unit of carbon metabolism in enteric bacteria since it is involved in the regulation of adenylate cyclase (AC) and therefore in carbon catabolite repression trough the control of the catabolite repressor protein (CRP) (Figure 5). In addition, it also interacts with several non-PTS permeases and glycerol kinase to inhibit their activity (inducer exclusion) [33].


Adaptative biochemical pathways and regulatory networks in Klebsiella oxytoca BAS-10 producing a biotechnologically relevant exopolysaccharide during Fe(III)-citrate fermentation.

Gallo G, Baldi F, Renzone G, Gallo M, Cordaro A, Scaloni A, Puglia AM - Microb. Cell Fact. (2012)

Regulatory network controlling the expression or the activity ofK. oxytocaBAS-10 differentially abundant proteins. The relationships are reported according to EcoCyc database [23], Bott (1997) [1], Salmon et al. (2005) [34] and Kumar et al. (2011) [49]. Dashed lines refer to an indirect relationship.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3539929&req=5

Figure 5: Regulatory network controlling the expression or the activity ofK. oxytocaBAS-10 differentially abundant proteins. The relationships are reported according to EcoCyc database [23], Bott (1997) [1], Salmon et al. (2005) [34] and Kumar et al. (2011) [49]. Dashed lines refer to an indirect relationship.
Mentions: The proteomic comparison showed down-regulation in anaerobic FEC of EIIAGlc, a component of bacterial phosphoenolpyruvate (PEP): carbohydrate phosphotransferase system (PTS), which was revealed as two protein spots differing for Mw in 2D-maps (Table 1, Figures 2 and 3; Additional file 1 Table S1 and Figure S2). The differential regulation of EIIAGlc may be related to the differential regulation of central carbon metabolism enzymes. In fact, in both Gram-negative and Gram-positive bacteria PTS consists of several factors interacting with different regulatory proteins thus controlling glucose metabolism and many other cellular functions [33]. In particular, EIIAGlc is the central processing unit of carbon metabolism in enteric bacteria since it is involved in the regulation of adenylate cyclase (AC) and therefore in carbon catabolite repression trough the control of the catabolite repressor protein (CRP) (Figure 5). In addition, it also interacts with several non-PTS permeases and glycerol kinase to inhibit their activity (inducer exclusion) [33].

Bottom Line: Unlikely other enterobacteria, BAS-10 is able to grow on Fe(III)-citrate as sole carbon and energy source, yielding acetic acid and CO2 coupled with Fe(III) reduction to Fe(II) and showing unusual physiological characteristics.The protein differential regulation seems to ensure efficient cell growth coupled with EPS production by adapting metabolic and biochemical processes in order to face iron toxicity and to optimize energy production.Differential proteomics provided insights on the molecular mechanisms necessary for anaeorobic utilization of Fe(III)-citrate in a biotechnologically promising enterobacteriun, also revealing genes that can be targeted for the rational design of high-yielding EPS producer strains.

View Article: PubMed Central - HTML - PubMed

Affiliation: Dipartimento di Scienze e Tecnologie Molecolari e Biomolecolari (STEMBIO), Università di Palermo Viale delle Scienze, ed, 16, Parco d'Orleans II, Palermo, 90128, Italy. giumir@msn.com

ABSTRACT

Background: A bacterial strain previously isolated from pyrite mine drainage and named BAS-10 was tentatively identified as Klebsiella oxytoca. Unlikely other enterobacteria, BAS-10 is able to grow on Fe(III)-citrate as sole carbon and energy source, yielding acetic acid and CO2 coupled with Fe(III) reduction to Fe(II) and showing unusual physiological characteristics. In fact, under this growth condition, BAS-10 produces an exopolysaccharide (EPS) having a high rhamnose content and metal-binding properties, whose biotechnological applications were proven as very relevant.

Results: Further phylogenetic analysis, based on 16S rDNA sequence, definitively confirmed that BAS-10 belongs to K. oxytoca species. In order to rationalize the biochemical peculiarities of this unusual enterobacteriun, combined 2D-Differential Gel Electrophoresis (2D-DIGE) analysis and mass spectrometry procedures were used to investigate its proteomic changes: i) under aerobic or anaerobic cultivation with Fe(III)-citrate as sole carbon source; ii) under anaerobic cultivations using Na(I)-citrate or Fe(III)-citrate as sole carbon source. Combining data from these differential studies peculiar levels of outer membrane proteins, key regulatory factors of carbon and nitrogen metabolism and enzymes involved in TCA cycle and sugar biosynthesis or required for citrate fermentation and stress response during anaerobic growth on Fe(III)-citrate were revealed. The protein differential regulation seems to ensure efficient cell growth coupled with EPS production by adapting metabolic and biochemical processes in order to face iron toxicity and to optimize energy production.

Conclusion: Differential proteomics provided insights on the molecular mechanisms necessary for anaeorobic utilization of Fe(III)-citrate in a biotechnologically promising enterobacteriun, also revealing genes that can be targeted for the rational design of high-yielding EPS producer strains.

Show MeSH
Related in: MedlinePlus