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PimT, an amino acid exporter controls polyene production via secretion of the quorum sensing pimaricin-inducer PI-factor in Streptomyces natalensis.

Vicente CM, Santos-Aberturas J, Guerra SM, Payero TD, Martín JF, Aparicio JF - Microb. Cell Fact. (2009)

Bottom Line: Interestingly, the mutant displayed 65% loss of pimaricin production, and also 50% decrease in the production of PI, indicating that PimT is used as PI-factor exporter, and suggesting that the effect in antifungal production might be due to limited secretion of the inducer.This report describes the involvement of an amino acid exporter (encoded by pimT in the vicinity of the pimaricin cluster) in modulating the expression of antibiotic biosynthetic genes via secretion of the quorum-sensing pimaricin-inducer PI-factor.The discovery of the participation of amino acid exporters in a signal transduction cascade for the production of polyene macrolides is unexpected, and represents an important step forward towards understanding the regulatory network for polyene regulation.

View Article: PubMed Central - HTML - PubMed

Affiliation: Instituto de Biotecnología INBIOTEC, 24006 León, Spain. jesus.aparicio@unileon.es.

ABSTRACT

Background: Polyenes represent a major class of antifungal agents characterised by the presence of a series of conjugated double bonds in their planar hydroxylated macrolide ring structure. Despite their general interest, very little is known about the factors that modulate their biosynthesis. Among these factors, we have recently discovered a new inducing compound (PI-factor) in the pimaricin producer Streptomyces natalensis, which elicits polyene production in a manner characteristic of quorum sensing. Here, we describe the involvement of an amino-acid exporter from S. natalensis in modulating the expression of pimaricin biosynthetic genes via secretion of the quorum-sensing pimaricin-inducer PI-factor.

Results: Adjacent to the pimaricin gene cluster lies a member of the RhtB family of amino-acid exporters. Gene deletion and complementation experiments provided evidence for a role for PimT in the export of L-homoserine, L-serine, and L-homoserine lactone. Expression of the gene was shown to be induced by homoserine and by the quorum-sensing pimaricin-inducer PI-factor. Interestingly, the mutant displayed 65% loss of pimaricin production, and also 50% decrease in the production of PI, indicating that PimT is used as PI-factor exporter, and suggesting that the effect in antifungal production might be due to limited secretion of the inducer.

Conclusion: This report describes the involvement of an amino acid exporter (encoded by pimT in the vicinity of the pimaricin cluster) in modulating the expression of antibiotic biosynthetic genes via secretion of the quorum-sensing pimaricin-inducer PI-factor. The discovery of the participation of amino acid exporters in a signal transduction cascade for the production of polyene macrolides is unexpected, and represents an important step forward towards understanding the regulatory network for polyene regulation. Additionally, this finding constitutes the first detailed characterization of an amino-acid exporter in an Actinomycete, and to our knowledge, the first evidence for the implication of this type of exporters in quorum sensing.

No MeSH data available.


Related in: MedlinePlus

Replacement of PimT reduces pimaricin production and gene complementation restores antifungal biosynthesis. Production of pimaricin in YEME medium (right panels). A) solid triangles indicate production by the wild type strain, open triangles the production by the ΔpimT strain. B) black squares indicate the production by the wild type strain harboring pSET152neo (control), white squares the production by the ΔpimT strain complemented with pimT, and grey squares the production by the ΔpimT strain harboring pSET152neo. Data are the average of three triplicate flasks. Vertical bars indicate the standard deviation values. Growth curves are shown at the left panels.
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Figure 4: Replacement of PimT reduces pimaricin production and gene complementation restores antifungal biosynthesis. Production of pimaricin in YEME medium (right panels). A) solid triangles indicate production by the wild type strain, open triangles the production by the ΔpimT strain. B) black squares indicate the production by the wild type strain harboring pSET152neo (control), white squares the production by the ΔpimT strain complemented with pimT, and grey squares the production by the ΔpimT strain harboring pSET152neo. Data are the average of three triplicate flasks. Vertical bars indicate the standard deviation values. Growth curves are shown at the left panels.

Mentions: The fermentation broth produced by the mutant strain generated by gene replacement, S. natalensis ΔpimT, was extracted with butanol and analyzed for the presence of pimaricin. The high performance liquid chromatography (HPLC) analysis indicated that pimaricin production in the mutant strain ΔpimT, was only about 35% of the pimaricin accumulated by the wild type strain at 96 h (0.73 g/l) (Fig. 4A). Given that both strains showed identical growth curves, this result prompted further investigation of the possible reasons for the markedly lower pimaricin production.


PimT, an amino acid exporter controls polyene production via secretion of the quorum sensing pimaricin-inducer PI-factor in Streptomyces natalensis.

Vicente CM, Santos-Aberturas J, Guerra SM, Payero TD, Martín JF, Aparicio JF - Microb. Cell Fact. (2009)

Replacement of PimT reduces pimaricin production and gene complementation restores antifungal biosynthesis. Production of pimaricin in YEME medium (right panels). A) solid triangles indicate production by the wild type strain, open triangles the production by the ΔpimT strain. B) black squares indicate the production by the wild type strain harboring pSET152neo (control), white squares the production by the ΔpimT strain complemented with pimT, and grey squares the production by the ΔpimT strain harboring pSET152neo. Data are the average of three triplicate flasks. Vertical bars indicate the standard deviation values. Growth curves are shown at the left panels.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2698837&req=5

Figure 4: Replacement of PimT reduces pimaricin production and gene complementation restores antifungal biosynthesis. Production of pimaricin in YEME medium (right panels). A) solid triangles indicate production by the wild type strain, open triangles the production by the ΔpimT strain. B) black squares indicate the production by the wild type strain harboring pSET152neo (control), white squares the production by the ΔpimT strain complemented with pimT, and grey squares the production by the ΔpimT strain harboring pSET152neo. Data are the average of three triplicate flasks. Vertical bars indicate the standard deviation values. Growth curves are shown at the left panels.
Mentions: The fermentation broth produced by the mutant strain generated by gene replacement, S. natalensis ΔpimT, was extracted with butanol and analyzed for the presence of pimaricin. The high performance liquid chromatography (HPLC) analysis indicated that pimaricin production in the mutant strain ΔpimT, was only about 35% of the pimaricin accumulated by the wild type strain at 96 h (0.73 g/l) (Fig. 4A). Given that both strains showed identical growth curves, this result prompted further investigation of the possible reasons for the markedly lower pimaricin production.

Bottom Line: Interestingly, the mutant displayed 65% loss of pimaricin production, and also 50% decrease in the production of PI, indicating that PimT is used as PI-factor exporter, and suggesting that the effect in antifungal production might be due to limited secretion of the inducer.This report describes the involvement of an amino acid exporter (encoded by pimT in the vicinity of the pimaricin cluster) in modulating the expression of antibiotic biosynthetic genes via secretion of the quorum-sensing pimaricin-inducer PI-factor.The discovery of the participation of amino acid exporters in a signal transduction cascade for the production of polyene macrolides is unexpected, and represents an important step forward towards understanding the regulatory network for polyene regulation.

View Article: PubMed Central - HTML - PubMed

Affiliation: Instituto de Biotecnología INBIOTEC, 24006 León, Spain. jesus.aparicio@unileon.es.

ABSTRACT

Background: Polyenes represent a major class of antifungal agents characterised by the presence of a series of conjugated double bonds in their planar hydroxylated macrolide ring structure. Despite their general interest, very little is known about the factors that modulate their biosynthesis. Among these factors, we have recently discovered a new inducing compound (PI-factor) in the pimaricin producer Streptomyces natalensis, which elicits polyene production in a manner characteristic of quorum sensing. Here, we describe the involvement of an amino-acid exporter from S. natalensis in modulating the expression of pimaricin biosynthetic genes via secretion of the quorum-sensing pimaricin-inducer PI-factor.

Results: Adjacent to the pimaricin gene cluster lies a member of the RhtB family of amino-acid exporters. Gene deletion and complementation experiments provided evidence for a role for PimT in the export of L-homoserine, L-serine, and L-homoserine lactone. Expression of the gene was shown to be induced by homoserine and by the quorum-sensing pimaricin-inducer PI-factor. Interestingly, the mutant displayed 65% loss of pimaricin production, and also 50% decrease in the production of PI, indicating that PimT is used as PI-factor exporter, and suggesting that the effect in antifungal production might be due to limited secretion of the inducer.

Conclusion: This report describes the involvement of an amino acid exporter (encoded by pimT in the vicinity of the pimaricin cluster) in modulating the expression of antibiotic biosynthetic genes via secretion of the quorum-sensing pimaricin-inducer PI-factor. The discovery of the participation of amino acid exporters in a signal transduction cascade for the production of polyene macrolides is unexpected, and represents an important step forward towards understanding the regulatory network for polyene regulation. Additionally, this finding constitutes the first detailed characterization of an amino-acid exporter in an Actinomycete, and to our knowledge, the first evidence for the implication of this type of exporters in quorum sensing.

No MeSH data available.


Related in: MedlinePlus