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Characterisation of porin genes from Mycobacterium fortuitum and their impact on growth.

Sharbati S, Schramm K, Rempel S, Wang H, Andrich R, Tykiel V, Kunisch R, Lewin A - BMC Microbiol. (2009)

Bottom Line: Comparative expression analysis of porM genes revealed divergent porin expression among analysed M. fortuitum strains.Repression of the expression of porins by antisense technique decreased the growth rates of different M. fortuitum.The effects of over-expression of porM1 as well as porM2 varied depending on the strain and the concentration of antibiotic added to the medium and indicated that PorM1 and PorM2 enhance the growth of M. fortuitum strains, but also the diffusion of the antibiotic kanamycin into the cells.

View Article: PubMed Central - HTML - PubMed

Affiliation: Freie Universit├Ąt Berlin, Institute of Veterinary Biochemistry, Berlin, Germany. sharbati@zedat.fu-berlin.de

ABSTRACT

Background: Highly pathogenic mycobacteria like Mycobacterium tuberculosis are characterised by their slow growth and their ability to reside and multiply in the very hostile phagosomal environment and a correlation between the growth rate of mycobacteria and their pathogenicity has been hypothesised. Here, porin genes from M. fortuitum were cloned and characterised to address their impact on the growth rate of fast-growing and pathogenic mycobacteria.

Results: Two genes encoding porins orthologous to MspA from M. smegmatis, porM1 and porM2, were cloned from M. fortuitum strains, which were originally isolated from human patients. Both porin genes were at least partially able to complement the mutations of a M. smegmatis mutant strain lacking the genes mspA and mspC with respect to the growth rate. PorM1 and porM2 were present in different strains of M. fortuitum including the type strain. Comparative expression analysis of porM genes revealed divergent porin expression among analysed M. fortuitum strains. Repression of the expression of porins by antisense technique decreased the growth rates of different M. fortuitum. The effects of over-expression of porM1 as well as porM2 varied depending on the strain and the concentration of antibiotic added to the medium and indicated that PorM1 and PorM2 enhance the growth of M. fortuitum strains, but also the diffusion of the antibiotic kanamycin into the cells.

Conclusion: This study demonstrates the important role of porin expression in growth as well as antibiotic susceptibility of the opportunistic bacterium M. fortuitum.

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Related in: MedlinePlus

Growth rate of the M. fortuitum strains 10851/03, 10860/03 and DSM 46621. The growth rate of the strains was measured by quantification of the ATP-content [displayed as relative light units (RLU)] in broth cultures.
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Figure 1: Growth rate of the M. fortuitum strains 10851/03, 10860/03 and DSM 46621. The growth rate of the strains was measured by quantification of the ATP-content [displayed as relative light units (RLU)] in broth cultures.

Mentions: Comparison of growth rates of the employed strains was performed in broth by measuring the ATP content of the cultures. Compared to other methods for growth measurements such as OD-measurement, cfu-counting or quantification of DNA, the quantification of the ATP-content has the advantage of not being biased by clumping of cultures or by inability of viable bacteria to grow on agar if plated from a broth culture or by occurrence of dead bacteria. We therefore chose this method for the comparison of the growth rates of the three strains. However, the ATP content of bacteria may vary depending on their physiological state and it therefore has to be considered as a surrogate growth marker. As shown in Figure 1 (also see Additional file 1), strain 10851/03 only grew very poorly, while strains 10860/03 and DSM 46621 multiplied strongly from day ten until day 14 or until day 15, respectively.


Characterisation of porin genes from Mycobacterium fortuitum and their impact on growth.

Sharbati S, Schramm K, Rempel S, Wang H, Andrich R, Tykiel V, Kunisch R, Lewin A - BMC Microbiol. (2009)

Growth rate of the M. fortuitum strains 10851/03, 10860/03 and DSM 46621. The growth rate of the strains was measured by quantification of the ATP-content [displayed as relative light units (RLU)] in broth cultures.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2651896&req=5

Figure 1: Growth rate of the M. fortuitum strains 10851/03, 10860/03 and DSM 46621. The growth rate of the strains was measured by quantification of the ATP-content [displayed as relative light units (RLU)] in broth cultures.
Mentions: Comparison of growth rates of the employed strains was performed in broth by measuring the ATP content of the cultures. Compared to other methods for growth measurements such as OD-measurement, cfu-counting or quantification of DNA, the quantification of the ATP-content has the advantage of not being biased by clumping of cultures or by inability of viable bacteria to grow on agar if plated from a broth culture or by occurrence of dead bacteria. We therefore chose this method for the comparison of the growth rates of the three strains. However, the ATP content of bacteria may vary depending on their physiological state and it therefore has to be considered as a surrogate growth marker. As shown in Figure 1 (also see Additional file 1), strain 10851/03 only grew very poorly, while strains 10860/03 and DSM 46621 multiplied strongly from day ten until day 14 or until day 15, respectively.

Bottom Line: Comparative expression analysis of porM genes revealed divergent porin expression among analysed M. fortuitum strains.Repression of the expression of porins by antisense technique decreased the growth rates of different M. fortuitum.The effects of over-expression of porM1 as well as porM2 varied depending on the strain and the concentration of antibiotic added to the medium and indicated that PorM1 and PorM2 enhance the growth of M. fortuitum strains, but also the diffusion of the antibiotic kanamycin into the cells.

View Article: PubMed Central - HTML - PubMed

Affiliation: Freie Universit├Ąt Berlin, Institute of Veterinary Biochemistry, Berlin, Germany. sharbati@zedat.fu-berlin.de

ABSTRACT

Background: Highly pathogenic mycobacteria like Mycobacterium tuberculosis are characterised by their slow growth and their ability to reside and multiply in the very hostile phagosomal environment and a correlation between the growth rate of mycobacteria and their pathogenicity has been hypothesised. Here, porin genes from M. fortuitum were cloned and characterised to address their impact on the growth rate of fast-growing and pathogenic mycobacteria.

Results: Two genes encoding porins orthologous to MspA from M. smegmatis, porM1 and porM2, were cloned from M. fortuitum strains, which were originally isolated from human patients. Both porin genes were at least partially able to complement the mutations of a M. smegmatis mutant strain lacking the genes mspA and mspC with respect to the growth rate. PorM1 and porM2 were present in different strains of M. fortuitum including the type strain. Comparative expression analysis of porM genes revealed divergent porin expression among analysed M. fortuitum strains. Repression of the expression of porins by antisense technique decreased the growth rates of different M. fortuitum. The effects of over-expression of porM1 as well as porM2 varied depending on the strain and the concentration of antibiotic added to the medium and indicated that PorM1 and PorM2 enhance the growth of M. fortuitum strains, but also the diffusion of the antibiotic kanamycin into the cells.

Conclusion: This study demonstrates the important role of porin expression in growth as well as antibiotic susceptibility of the opportunistic bacterium M. fortuitum.

Show MeSH
Related in: MedlinePlus