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Role of dihydrolipoamide dehydrogenase in regulation of raffinose transport in Streptococcus pneumoniae

Tyx, Robert E; Roche-Hakansson, Hazeline and Hakansson, Anders P LU (2011) In Journal of Bacteriology 193(14). p.24-3512
Abstract

Streptococcus pneumoniae strains lacking the enzyme dihydrolipoamide dehydrogenase (DLDH) show markedly reduced ability to grow on raffinose and stachyose as sole carbon sources. Import of these sugars occurs through the previously characterized raffinose ATP-binding cassette (ABC) transport system, encoded by the raf operon, that lacks the necessary ATP-binding protein. In this study, we identified the raffinose ATP-binding protein RafK and showed that it was directly involved in raffinose and stachyose import. RafK carries a C-terminal regulatory domain present in a subset of ATP-binding proteins that has been involved in both direct regulation of transporter activity (inducer exclusion) and transcription of transporter genes.... (More)

Streptococcus pneumoniae strains lacking the enzyme dihydrolipoamide dehydrogenase (DLDH) show markedly reduced ability to grow on raffinose and stachyose as sole carbon sources. Import of these sugars occurs through the previously characterized raffinose ATP-binding cassette (ABC) transport system, encoded by the raf operon, that lacks the necessary ATP-binding protein. In this study, we identified the raffinose ATP-binding protein RafK and showed that it was directly involved in raffinose and stachyose import. RafK carries a C-terminal regulatory domain present in a subset of ATP-binding proteins that has been involved in both direct regulation of transporter activity (inducer exclusion) and transcription of transporter genes. Pneumococci lacking RafK showed a 50- to 80-fold reduction in expression of the raf operon genes aga (alpha-galactosidase) and rafEFG (raffinose substrate binding and permease genes), and both glucose and sucrose inhibited raffinose uptake through inducer exclusion. Like RafK, the presence of DLDH also activated the expression of raf operon genes, as DLDH-negative pneumococci showed a significantly decreased expression of aga and rafEFG, but DLDH did not regulate rafK or the putative regulatory genes rafR and rafS. DLDH also bound directly to RafK both in vitro and in vivo, indicating the possibility that DLDH regulates raffinose transport by a direct interaction with the regulatory domain of the transporter. Finally, although not as attenuated as DLDH-negative bacteria, pneumococci lacking RafK were significantly outcompeted by wild-type bacteria in colonization experiments of murine lung and nasopharynx, indicating a role for raffinose and stachyose transport in vivo.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Animals, Bacterial Proteins, Biological Transport, Dihydrolipoamide Dehydrogenase, Gene Expression Regulation, Bacterial, Humans, Mice, Pneumococcal Infections, Raffinose, Streptococcus pneumoniae
in
Journal of Bacteriology
volume
193
issue
14
pages
13 pages
publisher
American Society for Microbiology
external identifiers
  • scopus:79960412412
ISSN
0021-9193
DOI
10.1128/JB.01410-10
language
English
LU publication?
yes
id
a76e0f7e-a93c-4606-8e7f-cf87c1a9a358
date added to LUP
2016-05-21 10:50:32
date last changed
2017-01-08 05:54:36
@article{a76e0f7e-a93c-4606-8e7f-cf87c1a9a358,
  abstract     = {<p>Streptococcus pneumoniae strains lacking the enzyme dihydrolipoamide dehydrogenase (DLDH) show markedly reduced ability to grow on raffinose and stachyose as sole carbon sources. Import of these sugars occurs through the previously characterized raffinose ATP-binding cassette (ABC) transport system, encoded by the raf operon, that lacks the necessary ATP-binding protein. In this study, we identified the raffinose ATP-binding protein RafK and showed that it was directly involved in raffinose and stachyose import. RafK carries a C-terminal regulatory domain present in a subset of ATP-binding proteins that has been involved in both direct regulation of transporter activity (inducer exclusion) and transcription of transporter genes. Pneumococci lacking RafK showed a 50- to 80-fold reduction in expression of the raf operon genes aga (alpha-galactosidase) and rafEFG (raffinose substrate binding and permease genes), and both glucose and sucrose inhibited raffinose uptake through inducer exclusion. Like RafK, the presence of DLDH also activated the expression of raf operon genes, as DLDH-negative pneumococci showed a significantly decreased expression of aga and rafEFG, but DLDH did not regulate rafK or the putative regulatory genes rafR and rafS. DLDH also bound directly to RafK both in vitro and in vivo, indicating the possibility that DLDH regulates raffinose transport by a direct interaction with the regulatory domain of the transporter. Finally, although not as attenuated as DLDH-negative bacteria, pneumococci lacking RafK were significantly outcompeted by wild-type bacteria in colonization experiments of murine lung and nasopharynx, indicating a role for raffinose and stachyose transport in vivo.</p>},
  author       = {Tyx, Robert E and Roche-Hakansson, Hazeline and Hakansson, Anders P},
  issn         = {0021-9193},
  keyword      = {Animals,Bacterial Proteins,Biological Transport,Dihydrolipoamide Dehydrogenase,Gene Expression Regulation, Bacterial,Humans,Mice,Pneumococcal Infections,Raffinose,Streptococcus pneumoniae},
  language     = {eng},
  number       = {14},
  pages        = {24--3512},
  publisher    = {American Society for Microbiology},
  series       = {Journal of Bacteriology},
  title        = {Role of dihydrolipoamide dehydrogenase in regulation of raffinose transport in Streptococcus pneumoniae},
  url          = {http://dx.doi.org/10.1128/JB.01410-10},
  volume       = {193},
  year         = {2011},
}