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Polysialic and colanic acids metabolism in Escherichia coli K92 is regulated by RcsA and RcsB.

Navasa N, Rodríguez-Aparicio L, Ferrero MÁ, Monteagudo-Mera A, Martínez-Blanco H - Biosci. Rep. (2013)

Bottom Line: Deletion of either rcsA or rcsB genes resulted in decreased expression of cps (CA biosynthesis cluster) at 19°C and 37°C, but only CA production was reduced at 19°C.Concerning PA, both deletions enhanced its synthesis at 37°C, which does not correlate with the reduced kps (PA biosynthesis cluster) expression observed in the rcsB mutant.Although RcsA and RcsB acted as negative regulators of PA synthesis at 37°C, their absence did not reestablish PA expression at low temperatures, despite the deletion of rcsB resulting in enhanced kps expression.

View Article: PubMed Central - PubMed

Affiliation: Departamento de Biología Molecular, Área de Bioquímica y Biología Molecular, Universidad de León, Campus de Vegazana, 24071 León, Spain.

ABSTRACT
We have shown previously that Escherichia coli K92 produces two different capsular polymers known as CA (colanic acid) and PA (polysialic acid) in a thermoregulated manner. The complex Rcs phosphorelay is largely related to the regulation of CA synthesis. Through deletion of rscA and rscB genes, we show that the Rcs system is involved in the regulation of both CA and PA synthesis in E. coli K92. Deletion of either rcsA or rcsB genes resulted in decreased expression of cps (CA biosynthesis cluster) at 19°C and 37°C, but only CA production was reduced at 19°C. Concerning PA, both deletions enhanced its synthesis at 37°C, which does not correlate with the reduced kps (PA biosynthesis cluster) expression observed in the rcsB mutant. Under this condition, expression of the nan operon responsible for PA catabolism was greatly reduced. Although RcsA and RcsB acted as negative regulators of PA synthesis at 37°C, their absence did not reestablish PA expression at low temperatures, despite the deletion of rcsB resulting in enhanced kps expression. Finally, our results revealed that RcsB controlled the expression of several genes (dsrA, rfaH, h-ns and slyA) involved in the thermoregulation of CA and PA synthesis, indicating that RcsB is part of a complex regulatory mechanism governing the surface appearance in E. coli.

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PA production by E. coli K92, E. coli K92ΔrcsA and E. coli K92ΔrcsB growth in MM containing Xyl–Asn (A) or Glc–Pro (B) at 37°CNS, no statistically significant differences; *P<0.05, **P=0.005 by Student's t test.
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Figure 5: PA production by E. coli K92, E. coli K92ΔrcsA and E. coli K92ΔrcsB growth in MM containing Xyl–Asn (A) or Glc–Pro (B) at 37°CNS, no statistically significant differences; *P<0.05, **P=0.005 by Student's t test.

Mentions: Deletion of either rcsA or rcsB resulted in increased PA production under all conditions tested (Figure 5). This increment was not significant when E. coli K92ΔrcsA was grown in Xyl–Asn MM. Dialysis of the supernatants ensured that all sialic acid detected belonged to a high molecular mass structure. These results show that RcsA and RcsB act, directly or indirectly, to repress PA synthesis in E. coli K92. However, this effect was insufficient to overcome inhibition of PA capsule synthesis at low temperatures, since neither E. coli K92ΔrcsA nor E. coli K92ΔrcsB were able to generate PA synthesis at 19°C (results not shown).


Polysialic and colanic acids metabolism in Escherichia coli K92 is regulated by RcsA and RcsB.

Navasa N, Rodríguez-Aparicio L, Ferrero MÁ, Monteagudo-Mera A, Martínez-Blanco H - Biosci. Rep. (2013)

PA production by E. coli K92, E. coli K92ΔrcsA and E. coli K92ΔrcsB growth in MM containing Xyl–Asn (A) or Glc–Pro (B) at 37°CNS, no statistically significant differences; *P<0.05, **P=0.005 by Student's t test.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3673037&req=5

Figure 5: PA production by E. coli K92, E. coli K92ΔrcsA and E. coli K92ΔrcsB growth in MM containing Xyl–Asn (A) or Glc–Pro (B) at 37°CNS, no statistically significant differences; *P<0.05, **P=0.005 by Student's t test.
Mentions: Deletion of either rcsA or rcsB resulted in increased PA production under all conditions tested (Figure 5). This increment was not significant when E. coli K92ΔrcsA was grown in Xyl–Asn MM. Dialysis of the supernatants ensured that all sialic acid detected belonged to a high molecular mass structure. These results show that RcsA and RcsB act, directly or indirectly, to repress PA synthesis in E. coli K92. However, this effect was insufficient to overcome inhibition of PA capsule synthesis at low temperatures, since neither E. coli K92ΔrcsA nor E. coli K92ΔrcsB were able to generate PA synthesis at 19°C (results not shown).

Bottom Line: Deletion of either rcsA or rcsB genes resulted in decreased expression of cps (CA biosynthesis cluster) at 19°C and 37°C, but only CA production was reduced at 19°C.Concerning PA, both deletions enhanced its synthesis at 37°C, which does not correlate with the reduced kps (PA biosynthesis cluster) expression observed in the rcsB mutant.Although RcsA and RcsB acted as negative regulators of PA synthesis at 37°C, their absence did not reestablish PA expression at low temperatures, despite the deletion of rcsB resulting in enhanced kps expression.

View Article: PubMed Central - PubMed

Affiliation: Departamento de Biología Molecular, Área de Bioquímica y Biología Molecular, Universidad de León, Campus de Vegazana, 24071 León, Spain.

ABSTRACT
We have shown previously that Escherichia coli K92 produces two different capsular polymers known as CA (colanic acid) and PA (polysialic acid) in a thermoregulated manner. The complex Rcs phosphorelay is largely related to the regulation of CA synthesis. Through deletion of rscA and rscB genes, we show that the Rcs system is involved in the regulation of both CA and PA synthesis in E. coli K92. Deletion of either rcsA or rcsB genes resulted in decreased expression of cps (CA biosynthesis cluster) at 19°C and 37°C, but only CA production was reduced at 19°C. Concerning PA, both deletions enhanced its synthesis at 37°C, which does not correlate with the reduced kps (PA biosynthesis cluster) expression observed in the rcsB mutant. Under this condition, expression of the nan operon responsible for PA catabolism was greatly reduced. Although RcsA and RcsB acted as negative regulators of PA synthesis at 37°C, their absence did not reestablish PA expression at low temperatures, despite the deletion of rcsB resulting in enhanced kps expression. Finally, our results revealed that RcsB controlled the expression of several genes (dsrA, rfaH, h-ns and slyA) involved in the thermoregulation of CA and PA synthesis, indicating that RcsB is part of a complex regulatory mechanism governing the surface appearance in E. coli.

Show MeSH
Related in: MedlinePlus