A <named-content content-type="genus-species">Rhodobacter sphaeroides</named-content> Protein Mechanistically Similar to <named-content content-type="genus-species">Escherichia coli</named-content> DksA Regulates Photosynthetic Growth

ABSTRACT DksA is a global regulatory protein that, together with the alarmone ppGpp, is required for the “stringent response” to nutrient starvation in the gammaproteobacterium Escherichia coli and for more moderate shifts between growth conditions. DksA modulates the expression of hundreds of genes...

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Autores principales: Christopher W. Lennon, Kimberly C. Lemmer, Jessica L. Irons, Max I. Sellman, Timothy J. Donohue, Richard L. Gourse, Wilma Ross
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Publicado: American Society for Microbiology 2014
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spelling oai:doaj.org-article:70153861838541a9926f5f4b38b4d5992021-11-15T15:47:38ZA <named-content content-type="genus-species">Rhodobacter sphaeroides</named-content> Protein Mechanistically Similar to <named-content content-type="genus-species">Escherichia coli</named-content> DksA Regulates Photosynthetic Growth10.1128/mBio.01105-142150-7511https://doaj.org/article/70153861838541a9926f5f4b38b4d5992014-07-01T00:00:00Zhttps://journals.asm.org/doi/10.1128/mBio.01105-14https://doaj.org/toc/2150-7511ABSTRACT DksA is a global regulatory protein that, together with the alarmone ppGpp, is required for the “stringent response” to nutrient starvation in the gammaproteobacterium Escherichia coli and for more moderate shifts between growth conditions. DksA modulates the expression of hundreds of genes, directly or indirectly. Mutants lacking a DksA homolog exhibit pleiotropic phenotypes in other gammaproteobacteria as well. Here we analyzed the DksA homolog RSP2654 in the more distantly related Rhodobacter sphaeroides, an alphaproteobacterium. RSP2654 is 42% identical and similar in length to E. coli DksA but lacks the Zn finger motif of the E. coli DksA globular domain. Deletion of the RSP2654 gene results in defects in photosynthetic growth, impaired utilization of amino acids, and an increase in fatty acid content. RSP2654 complements the growth and regulatory defects of an E. coli strain lacking the dksA gene and modulates transcription in vitro with E. coli RNA polymerase (RNAP) similarly to E. coli DksA. RSP2654 reduces RNAP-promoter complex stability in vitro with RNAPs from E. coli or R. sphaeroides, alone and synergistically with ppGpp, suggesting that even though it has limited sequence identity to E. coli DksA (DksAEc), it functions in a mechanistically similar manner. We therefore designate the RSP2654 protein DksARsp. Our work suggests that DksARsp has distinct and important physiological roles in alphaproteobacteria and will be useful for understanding structure-function relationships in DksA and the mechanism of synergy between DksA and ppGpp. IMPORTANCE The role of DksA has been analyzed primarily in the gammaproteobacteria, in which it is best understood for its role in control of the synthesis of the translation apparatus and amino acid biosynthesis. Our work suggests that DksA plays distinct and important physiological roles in alphaproteobacteria, including the control of photosynthesis in Rhodobacter sphaeroides. The study of DksARsp, should be useful for understanding structure-function relationships in the protein, including those that play a role in the little-understood synergy between DksA and ppGpp.Christopher W. LennonKimberly C. LemmerJessica L. IronsMax I. SellmanTimothy J. DonohueRichard L. GourseWilma RossAmerican Society for MicrobiologyarticleMicrobiologyQR1-502ENmBio, Vol 5, Iss 3 (2014)
institution DOAJ
collection DOAJ
language EN
topic Microbiology
QR1-502
spellingShingle Microbiology
QR1-502
Christopher W. Lennon
Kimberly C. Lemmer
Jessica L. Irons
Max I. Sellman
Timothy J. Donohue
Richard L. Gourse
Wilma Ross
A <named-content content-type="genus-species">Rhodobacter sphaeroides</named-content> Protein Mechanistically Similar to <named-content content-type="genus-species">Escherichia coli</named-content> DksA Regulates Photosynthetic Growth
description ABSTRACT DksA is a global regulatory protein that, together with the alarmone ppGpp, is required for the “stringent response” to nutrient starvation in the gammaproteobacterium Escherichia coli and for more moderate shifts between growth conditions. DksA modulates the expression of hundreds of genes, directly or indirectly. Mutants lacking a DksA homolog exhibit pleiotropic phenotypes in other gammaproteobacteria as well. Here we analyzed the DksA homolog RSP2654 in the more distantly related Rhodobacter sphaeroides, an alphaproteobacterium. RSP2654 is 42% identical and similar in length to E. coli DksA but lacks the Zn finger motif of the E. coli DksA globular domain. Deletion of the RSP2654 gene results in defects in photosynthetic growth, impaired utilization of amino acids, and an increase in fatty acid content. RSP2654 complements the growth and regulatory defects of an E. coli strain lacking the dksA gene and modulates transcription in vitro with E. coli RNA polymerase (RNAP) similarly to E. coli DksA. RSP2654 reduces RNAP-promoter complex stability in vitro with RNAPs from E. coli or R. sphaeroides, alone and synergistically with ppGpp, suggesting that even though it has limited sequence identity to E. coli DksA (DksAEc), it functions in a mechanistically similar manner. We therefore designate the RSP2654 protein DksARsp. Our work suggests that DksARsp has distinct and important physiological roles in alphaproteobacteria and will be useful for understanding structure-function relationships in DksA and the mechanism of synergy between DksA and ppGpp. IMPORTANCE The role of DksA has been analyzed primarily in the gammaproteobacteria, in which it is best understood for its role in control of the synthesis of the translation apparatus and amino acid biosynthesis. Our work suggests that DksA plays distinct and important physiological roles in alphaproteobacteria, including the control of photosynthesis in Rhodobacter sphaeroides. The study of DksARsp, should be useful for understanding structure-function relationships in the protein, including those that play a role in the little-understood synergy between DksA and ppGpp.
format article
author Christopher W. Lennon
Kimberly C. Lemmer
Jessica L. Irons
Max I. Sellman
Timothy J. Donohue
Richard L. Gourse
Wilma Ross
author_facet Christopher W. Lennon
Kimberly C. Lemmer
Jessica L. Irons
Max I. Sellman
Timothy J. Donohue
Richard L. Gourse
Wilma Ross
author_sort Christopher W. Lennon
title A <named-content content-type="genus-species">Rhodobacter sphaeroides</named-content> Protein Mechanistically Similar to <named-content content-type="genus-species">Escherichia coli</named-content> DksA Regulates Photosynthetic Growth
title_short A <named-content content-type="genus-species">Rhodobacter sphaeroides</named-content> Protein Mechanistically Similar to <named-content content-type="genus-species">Escherichia coli</named-content> DksA Regulates Photosynthetic Growth
title_full A <named-content content-type="genus-species">Rhodobacter sphaeroides</named-content> Protein Mechanistically Similar to <named-content content-type="genus-species">Escherichia coli</named-content> DksA Regulates Photosynthetic Growth
title_fullStr A <named-content content-type="genus-species">Rhodobacter sphaeroides</named-content> Protein Mechanistically Similar to <named-content content-type="genus-species">Escherichia coli</named-content> DksA Regulates Photosynthetic Growth
title_full_unstemmed A <named-content content-type="genus-species">Rhodobacter sphaeroides</named-content> Protein Mechanistically Similar to <named-content content-type="genus-species">Escherichia coli</named-content> DksA Regulates Photosynthetic Growth
title_sort <named-content content-type="genus-species">rhodobacter sphaeroides</named-content> protein mechanistically similar to <named-content content-type="genus-species">escherichia coli</named-content> dksa regulates photosynthetic growth
publisher American Society for Microbiology
publishDate 2014
url https://doaj.org/article/70153861838541a9926f5f4b38b4d599
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