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A TatABC-type Tat translocase is required for unimpaired aerobic growth of Corynebacterium glutamicum ATCC13032.

Oertel D, Schmitz S, Freudl R - PLoS ONE (2015)

Bottom Line: Furthermore, our results clearly show that TatB, besides TatA and TatC, is strictly required for unimpaired aerobic growth.In addition, TatB was also found to be essential for the secretion of a heterologous Tat-dependent model protein into the C. glutamicum culture supernatant.Together with our finding that expression of the C. glutamicum TatB in an E. coli ΔtatB mutant strain resulted in the formation of an active Tat translocase, our results clearly indicate that a TatABC translocase is used as the physiologically relevant functional unit for Tat-dependent protein translocation in C. glutamicum and, most likely, also in other TatB-containing Actinobacteria.

View Article: PubMed Central - PubMed

Affiliation: Institut für Bio- und Geowissenschaften 1, IBG1: Biotechnologie, Forschungszentrum Jülich GmbH, Jülich, Germany.

ABSTRACT
The twin-arginine translocation (Tat) system transports folded proteins across the cytoplasmic membrane of bacteria and the thylakoid membrane of plant chloroplasts. Escherichia coli and other Gram-negative bacteria possess a TatABC-type Tat translocase in which each of the three inner membrane proteins TatA, TatB, and TatC performs a mechanistically distinct function. In contrast, low-GC Gram-positive bacteria, such as Bacillus subtilis, use a TatAC-type minimal Tat translocase in which the TatB function is carried out by a bifunctional TatA. In high-GC Gram-positive Actinobacteria, such as Mycobacterium tuberculosis and Corynebacterium glutamicum, tatA, tatB, and tatC genes can be identified, suggesting that these organisms, just like E. coli, might use TatABC-type Tat translocases as well. However, since contrary to this view a previous study has suggested that C. glutamicum might in fact use a TatAC translocase with TatB only playing a minor role, we reexamined the requirement of TatB for Tat-dependent protein translocation in this microorganism. Under aerobic conditions, the misassembly of the Rieske iron-sulfur protein QcrA was identified as a major reason for the severe growth defect of Tat-defective C. glutamicum mutant strains. Furthermore, our results clearly show that TatB, besides TatA and TatC, is strictly required for unimpaired aerobic growth. In addition, TatB was also found to be essential for the secretion of a heterologous Tat-dependent model protein into the C. glutamicum culture supernatant. Together with our finding that expression of the C. glutamicum TatB in an E. coli ΔtatB mutant strain resulted in the formation of an active Tat translocase, our results clearly indicate that a TatABC translocase is used as the physiologically relevant functional unit for Tat-dependent protein translocation in C. glutamicum and, most likely, also in other TatB-containing Actinobacteria.

No MeSH data available.


Related in: MedlinePlus

The correct membrane assembly of the physiologically important Tat substrate QcrA is required for unimpaired growth of C. glutamicum.Cells were inoculated to an OD600 of 0.5 in 750 μl BHIS medium containing 100 μM IPTG and cultivated in 48-well FlowerPlates in a BioLector system for 48 h at 30°C, 1100 rpm under constant 85% relative humidity. Growth of the respective C. glutamicum strains, as indicated in the figure, was monitored as backscattered light (620 nm; signal gain factor 20) in 15 min intervals. The growth curves show one representative experiment of three independent biological replicates. Standard deviations are given for 10 selected time points. a.u.: arbitrary units.
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pone.0123413.g004: The correct membrane assembly of the physiologically important Tat substrate QcrA is required for unimpaired growth of C. glutamicum.Cells were inoculated to an OD600 of 0.5 in 750 μl BHIS medium containing 100 μM IPTG and cultivated in 48-well FlowerPlates in a BioLector system for 48 h at 30°C, 1100 rpm under constant 85% relative humidity. Growth of the respective C. glutamicum strains, as indicated in the figure, was monitored as backscattered light (620 nm; signal gain factor 20) in 15 min intervals. The growth curves show one representative experiment of three independent biological replicates. Standard deviations are given for 10 selected time points. a.u.: arbitrary units.

Mentions: To experimentally address these assumptions, we first compared the growth of a C. glutamicum wild-type strain possessing the pEKEx2 empty vector with the growth of pEKEx2-containing mutant strains C. glutamicum ΔqcrA and C. glutamicum ΔtatB using the BioLector micro-reactor cultivation device. As shown in Fig 4, compared to C. glutamicum wild-type, both mutant strains show a severely impaired growth under aerobic conditions. Notably, the growth behavior of both mutant strains is almost identical, a finding that would be consistent with mislocalization of QcrA being the actual cause for the growth defect associated with C. glutamicum tat mutant strains.


A TatABC-type Tat translocase is required for unimpaired aerobic growth of Corynebacterium glutamicum ATCC13032.

Oertel D, Schmitz S, Freudl R - PLoS ONE (2015)

The correct membrane assembly of the physiologically important Tat substrate QcrA is required for unimpaired growth of C. glutamicum.Cells were inoculated to an OD600 of 0.5 in 750 μl BHIS medium containing 100 μM IPTG and cultivated in 48-well FlowerPlates in a BioLector system for 48 h at 30°C, 1100 rpm under constant 85% relative humidity. Growth of the respective C. glutamicum strains, as indicated in the figure, was monitored as backscattered light (620 nm; signal gain factor 20) in 15 min intervals. The growth curves show one representative experiment of three independent biological replicates. Standard deviations are given for 10 selected time points. a.u.: arbitrary units.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4383559&req=5

pone.0123413.g004: The correct membrane assembly of the physiologically important Tat substrate QcrA is required for unimpaired growth of C. glutamicum.Cells were inoculated to an OD600 of 0.5 in 750 μl BHIS medium containing 100 μM IPTG and cultivated in 48-well FlowerPlates in a BioLector system for 48 h at 30°C, 1100 rpm under constant 85% relative humidity. Growth of the respective C. glutamicum strains, as indicated in the figure, was monitored as backscattered light (620 nm; signal gain factor 20) in 15 min intervals. The growth curves show one representative experiment of three independent biological replicates. Standard deviations are given for 10 selected time points. a.u.: arbitrary units.
Mentions: To experimentally address these assumptions, we first compared the growth of a C. glutamicum wild-type strain possessing the pEKEx2 empty vector with the growth of pEKEx2-containing mutant strains C. glutamicum ΔqcrA and C. glutamicum ΔtatB using the BioLector micro-reactor cultivation device. As shown in Fig 4, compared to C. glutamicum wild-type, both mutant strains show a severely impaired growth under aerobic conditions. Notably, the growth behavior of both mutant strains is almost identical, a finding that would be consistent with mislocalization of QcrA being the actual cause for the growth defect associated with C. glutamicum tat mutant strains.

Bottom Line: Furthermore, our results clearly show that TatB, besides TatA and TatC, is strictly required for unimpaired aerobic growth.In addition, TatB was also found to be essential for the secretion of a heterologous Tat-dependent model protein into the C. glutamicum culture supernatant.Together with our finding that expression of the C. glutamicum TatB in an E. coli ΔtatB mutant strain resulted in the formation of an active Tat translocase, our results clearly indicate that a TatABC translocase is used as the physiologically relevant functional unit for Tat-dependent protein translocation in C. glutamicum and, most likely, also in other TatB-containing Actinobacteria.

View Article: PubMed Central - PubMed

Affiliation: Institut für Bio- und Geowissenschaften 1, IBG1: Biotechnologie, Forschungszentrum Jülich GmbH, Jülich, Germany.

ABSTRACT
The twin-arginine translocation (Tat) system transports folded proteins across the cytoplasmic membrane of bacteria and the thylakoid membrane of plant chloroplasts. Escherichia coli and other Gram-negative bacteria possess a TatABC-type Tat translocase in which each of the three inner membrane proteins TatA, TatB, and TatC performs a mechanistically distinct function. In contrast, low-GC Gram-positive bacteria, such as Bacillus subtilis, use a TatAC-type minimal Tat translocase in which the TatB function is carried out by a bifunctional TatA. In high-GC Gram-positive Actinobacteria, such as Mycobacterium tuberculosis and Corynebacterium glutamicum, tatA, tatB, and tatC genes can be identified, suggesting that these organisms, just like E. coli, might use TatABC-type Tat translocases as well. However, since contrary to this view a previous study has suggested that C. glutamicum might in fact use a TatAC translocase with TatB only playing a minor role, we reexamined the requirement of TatB for Tat-dependent protein translocation in this microorganism. Under aerobic conditions, the misassembly of the Rieske iron-sulfur protein QcrA was identified as a major reason for the severe growth defect of Tat-defective C. glutamicum mutant strains. Furthermore, our results clearly show that TatB, besides TatA and TatC, is strictly required for unimpaired aerobic growth. In addition, TatB was also found to be essential for the secretion of a heterologous Tat-dependent model protein into the C. glutamicum culture supernatant. Together with our finding that expression of the C. glutamicum TatB in an E. coli ΔtatB mutant strain resulted in the formation of an active Tat translocase, our results clearly indicate that a TatABC translocase is used as the physiologically relevant functional unit for Tat-dependent protein translocation in C. glutamicum and, most likely, also in other TatB-containing Actinobacteria.

No MeSH data available.


Related in: MedlinePlus