TY  - JOUR
AU  - McDonald, Christopher
AU  - Jovanović, Goran
AU  - Wallace, B. A.
AU  - Ces, Oscar
AU  - Buck, Martin
PY  - 2017
UR  - https://imagine.imgge.bg.ac.rs/handle/123456789/1067
AB  - The phage shock protein (Psp) response maintains integrity of the inner membrane (IM) in response to extracytoplasmic stress conditions and is widely distributed amongst enterobacteria. Its central component PspA, a member of the IM30 peripheral membrane protein family, acts as a major effector of the system through its direct association with the IM. Under non-stress conditions PspA also negatively regulates its own expression via direct interaction with the AAA+ ATPase PspF. PspA has a counterpart in cyanobacteria called Vipp1, which is implicated in protection of the thylakoid membranes. PspA's and Vipp1's conserved N-terminal regions contain a putative amphipathic helix a (AHa) required for membrane binding. An adjacent amphipathic helix b (AHb) in PspA is required for imposing negative control upon PspF. Here, purified peptides derived from the putative AH regions of PspA and Vipp1 were used to directly probe their effector and regulatory functions. We observed direct membrane-binding of AHa derived peptides and an accompanying change in secondary structure from unstructured to alpha-helical establishing them as bona fide membrane-sensing AH's. The peptide-binding specificities and their effects on membrane stability depend on membrane anionic lipid content and stored curvature elastic stress, in agreement with full length PspA and Vipp1 protein functionalities. AHb of PspA inhibited the ATPase activity of PspF demonstrating its direct regulatory role. These findings provide new insight into the membrane binding and function of PspA and Vipp1 and establish that synthetic peptides can be used to probe the structure-function of the IM30 protein family.
PB  - Elsevier Science Bv, Amsterdam
T2  - Biochimica Et Biophysica Acta-Biomembranes
T1  - Structure and function of PspA and Vipp1 N-terminal peptides: Insights into the membrane stress sensing and mitigation
EP  - 39
IS  - 1
SP  - 28
VL  - 1859
DO  - 10.1016/j.bbamem.2016.10.018
ER  - 

@article{
author = "McDonald, Christopher and Jovanović, Goran and Wallace, B. A. and Ces, Oscar and Buck, Martin",
year = "2017",
abstract = "The phage shock protein (Psp) response maintains integrity of the inner membrane (IM) in response to extracytoplasmic stress conditions and is widely distributed amongst enterobacteria. Its central component PspA, a member of the IM30 peripheral membrane protein family, acts as a major effector of the system through its direct association with the IM. Under non-stress conditions PspA also negatively regulates its own expression via direct interaction with the AAA+ ATPase PspF. PspA has a counterpart in cyanobacteria called Vipp1, which is implicated in protection of the thylakoid membranes. PspA's and Vipp1's conserved N-terminal regions contain a putative amphipathic helix a (AHa) required for membrane binding. An adjacent amphipathic helix b (AHb) in PspA is required for imposing negative control upon PspF. Here, purified peptides derived from the putative AH regions of PspA and Vipp1 were used to directly probe their effector and regulatory functions. We observed direct membrane-binding of AHa derived peptides and an accompanying change in secondary structure from unstructured to alpha-helical establishing them as bona fide membrane-sensing AH's. The peptide-binding specificities and their effects on membrane stability depend on membrane anionic lipid content and stored curvature elastic stress, in agreement with full length PspA and Vipp1 protein functionalities. AHb of PspA inhibited the ATPase activity of PspF demonstrating its direct regulatory role. These findings provide new insight into the membrane binding and function of PspA and Vipp1 and establish that synthetic peptides can be used to probe the structure-function of the IM30 protein family.",
publisher = "Elsevier Science Bv, Amsterdam",
journal = "Biochimica Et Biophysica Acta-Biomembranes",
title = "Structure and function of PspA and Vipp1 N-terminal peptides: Insights into the membrane stress sensing and mitigation",
pages = "39-28",
number = "1",
volume = "1859",
doi = "10.1016/j.bbamem.2016.10.018"
}

McDonald, C., Jovanović, G., Wallace, B. A., Ces, O.,& Buck, M.. (2017). Structure and function of PspA and Vipp1 N-terminal peptides: Insights into the membrane stress sensing and mitigation. in Biochimica Et Biophysica Acta-Biomembranes
Elsevier Science Bv, Amsterdam., 1859(1), 28-39.
https://doi.org/10.1016/j.bbamem.2016.10.018

McDonald C, Jovanović G, Wallace BA, Ces O, Buck M. Structure and function of PspA and Vipp1 N-terminal peptides: Insights into the membrane stress sensing and mitigation. in Biochimica Et Biophysica Acta-Biomembranes. 2017;1859(1):28-39.
doi:10.1016/j.bbamem.2016.10.018 .

McDonald, Christopher, Jovanović, Goran, Wallace, B. A., Ces, Oscar, Buck, Martin, "Structure and function of PspA and Vipp1 N-terminal peptides: Insights into the membrane stress sensing and mitigation" in Biochimica Et Biophysica Acta-Biomembranes, 1859, no. 1 (2017):28-39,
https://doi.org/10.1016/j.bbamem.2016.10.018 . .

TY  - JOUR
AU  - Mehta, Parul
AU  - Jovanović, Goran
AU  - Ying, Liming
AU  - Buck, Martin
PY  - 2015
UR  - https://imagine.imgge.bg.ac.rs/handle/123456789/881
AB  - The bacterial cell envelope retains a highly dense cytoplasm. The properties of the cytoplasm change with the metabolic state of the cell, the logarithmic phase (log) being highly active and the stationary phase metabolically much slower. Under the differing growth phases, many different types of stress mechanisms are activated in order to maintain cellular integrity. One such response in enterobacteria is the phage shock protein (Psp) response that enables adaptation to the inner membrane (IM) stress. The Psp system consists of a transcriptional activator PspF, negative regulator PspA, signal sensors PspBC, with PspA and PspG acting as effectors. The single molecule imaging of the PspF showed the existence of dynamic communication between the nucleoid-bound states of PspF and membrane via negative regulator PspA and PspBC sensors. The movement of proteins in the cytoplasm of bacterial cells is often by passive diffusion. It is plausible that the dynamics of the biomolecules differs with the state of the cytoplasm depending on the growth phase. Therefore, the Psp response proteins might encounter the densely packed glass-like properties of the cytoplasm in the stationary phase, which can influence their cellular dynamics and function. By comparing the properties of the log and stationary phases, we find that the dynamics of PspF are influenced by the growth phase and may be controlled by the changes in the cytoplasmic fluidity.
PB  - Portland Press Ltd, London
T2  - Biochemical Society Transactions
T1  - Is the cellular and molecular machinery docile in the stationary phase of Escherichia coli?
EP  - 171
SP  - 168
VL  - 43
DO  - 10.1042/BST20140267
ER  - 

@article{
author = "Mehta, Parul and Jovanović, Goran and Ying, Liming and Buck, Martin",
year = "2015",
abstract = "The bacterial cell envelope retains a highly dense cytoplasm. The properties of the cytoplasm change with the metabolic state of the cell, the logarithmic phase (log) being highly active and the stationary phase metabolically much slower. Under the differing growth phases, many different types of stress mechanisms are activated in order to maintain cellular integrity. One such response in enterobacteria is the phage shock protein (Psp) response that enables adaptation to the inner membrane (IM) stress. The Psp system consists of a transcriptional activator PspF, negative regulator PspA, signal sensors PspBC, with PspA and PspG acting as effectors. The single molecule imaging of the PspF showed the existence of dynamic communication between the nucleoid-bound states of PspF and membrane via negative regulator PspA and PspBC sensors. The movement of proteins in the cytoplasm of bacterial cells is often by passive diffusion. It is plausible that the dynamics of the biomolecules differs with the state of the cytoplasm depending on the growth phase. Therefore, the Psp response proteins might encounter the densely packed glass-like properties of the cytoplasm in the stationary phase, which can influence their cellular dynamics and function. By comparing the properties of the log and stationary phases, we find that the dynamics of PspF are influenced by the growth phase and may be controlled by the changes in the cytoplasmic fluidity.",
publisher = "Portland Press Ltd, London",
journal = "Biochemical Society Transactions",
title = "Is the cellular and molecular machinery docile in the stationary phase of Escherichia coli?",
pages = "171-168",
volume = "43",
doi = "10.1042/BST20140267"
}

Mehta, P., Jovanović, G., Ying, L.,& Buck, M.. (2015). Is the cellular and molecular machinery docile in the stationary phase of Escherichia coli?. in Biochemical Society Transactions
Portland Press Ltd, London., 43, 168-171.
https://doi.org/10.1042/BST20140267

Mehta P, Jovanović G, Ying L, Buck M. Is the cellular and molecular machinery docile in the stationary phase of Escherichia coli?. in Biochemical Society Transactions. 2015;43:168-171.
doi:10.1042/BST20140267 .

Mehta, Parul, Jovanović, Goran, Ying, Liming, Buck, Martin, "Is the cellular and molecular machinery docile in the stationary phase of Escherichia coli?" in Biochemical Society Transactions, 43 (2015):168-171,
https://doi.org/10.1042/BST20140267 . .

TY  - JOUR
AU  - McDonald, Christopher
AU  - Jovanović, Goran
AU  - Ces, Oscar
AU  - Buck, Martin
PY  - 2015
UR  - https://imagine.imgge.bg.ac.rs/handle/123456789/838
AB  - Phage shock protein A (PspA), which is responsible for maintaining inner membrane integrity under stress in enterobacteria, and vesicle-inducting protein in plastids 1 (Vipp1), which functions for membrane maintenance and thylakoid biogenesis in cyanobacteria and plants, are similar peripheral membrane-binding proteins. Their homologous N-terminal amphipathic helices are required for membrane binding; however, the membrane features recognized and required for expressing their functionalities have remained largely uncharacterized. Rigorously controlled, in vitro methodologies with lipid vesicles and purified proteins were used in this study and provided the first biochemical and biophysical characterizations of membrane binding by PspA and Vipp1. Both proteins are found to sense stored curvature elastic (SCE) stress and anionic lipids within the membrane. PspA has an enhanced sensitivity for SCE stress and a higher affinity for the membrane than Vipp1. These variations in binding may be crucial for some of the proteins' differing roles in vivo. Assays probing the transcriptional regulatory function of PspA in the presence of vesicles showed that a relief of transcription inhibition occurs in an SCE stress-specific manner. This in vitro recapitulation of membrane stress-dependent transcription control suggests that the Psp response may be mounted in vivo when a cell's inner membrane experiences increased SCE stress. IMPORTANCE All cell types maintain the integrity of their membrane systems. One widely distributed membrane stress response system in bacteria is the phage shock protein (Psp) system. The central component, peripheral membrane protein PspA, which mitigates inner membrane stress in bacteria, has a counterpart, Vipp1, which functions for membrane maintenance and thylakoid biogenesis in plants and photosynthetic bacteria. Membrane association of both these proteins is accepted as playing a pivotal role in their functions. Here we show that direct membrane binding by PspA and Vipp1 is driven by two physio-chemical signals, one of which is membrane stress specific. Our work points to alleviation of membrane stored curvature elastic stress by amphipathic helix insertions as an attractive mechanism for membrane maintenance by PspA and Vipp1. Furthermore, the identification of a physical, stress-related membrane signal suggests a unilateral mechanism that promotes both binding of PspA and induction of the Psp response.
PB  - Amer Soc Microbiology, Washington
T2  - MBIO
T1  - Membrane Stored Curvature Elastic Stress Modulates Recruitment of Maintenance Proteins PspA and Vipp1
IS  - 5
VL  - 6
DO  - 10.1128/mBio.01188-15
ER  - 

@article{
author = "McDonald, Christopher and Jovanović, Goran and Ces, Oscar and Buck, Martin",
year = "2015",
abstract = "Phage shock protein A (PspA), which is responsible for maintaining inner membrane integrity under stress in enterobacteria, and vesicle-inducting protein in plastids 1 (Vipp1), which functions for membrane maintenance and thylakoid biogenesis in cyanobacteria and plants, are similar peripheral membrane-binding proteins. Their homologous N-terminal amphipathic helices are required for membrane binding; however, the membrane features recognized and required for expressing their functionalities have remained largely uncharacterized. Rigorously controlled, in vitro methodologies with lipid vesicles and purified proteins were used in this study and provided the first biochemical and biophysical characterizations of membrane binding by PspA and Vipp1. Both proteins are found to sense stored curvature elastic (SCE) stress and anionic lipids within the membrane. PspA has an enhanced sensitivity for SCE stress and a higher affinity for the membrane than Vipp1. These variations in binding may be crucial for some of the proteins' differing roles in vivo. Assays probing the transcriptional regulatory function of PspA in the presence of vesicles showed that a relief of transcription inhibition occurs in an SCE stress-specific manner. This in vitro recapitulation of membrane stress-dependent transcription control suggests that the Psp response may be mounted in vivo when a cell's inner membrane experiences increased SCE stress. IMPORTANCE All cell types maintain the integrity of their membrane systems. One widely distributed membrane stress response system in bacteria is the phage shock protein (Psp) system. The central component, peripheral membrane protein PspA, which mitigates inner membrane stress in bacteria, has a counterpart, Vipp1, which functions for membrane maintenance and thylakoid biogenesis in plants and photosynthetic bacteria. Membrane association of both these proteins is accepted as playing a pivotal role in their functions. Here we show that direct membrane binding by PspA and Vipp1 is driven by two physio-chemical signals, one of which is membrane stress specific. Our work points to alleviation of membrane stored curvature elastic stress by amphipathic helix insertions as an attractive mechanism for membrane maintenance by PspA and Vipp1. Furthermore, the identification of a physical, stress-related membrane signal suggests a unilateral mechanism that promotes both binding of PspA and induction of the Psp response.",
publisher = "Amer Soc Microbiology, Washington",
journal = "MBIO",
title = "Membrane Stored Curvature Elastic Stress Modulates Recruitment of Maintenance Proteins PspA and Vipp1",
number = "5",
volume = "6",
doi = "10.1128/mBio.01188-15"
}

McDonald, C., Jovanović, G., Ces, O.,& Buck, M.. (2015). Membrane Stored Curvature Elastic Stress Modulates Recruitment of Maintenance Proteins PspA and Vipp1. in MBIO
Amer Soc Microbiology, Washington., 6(5).
https://doi.org/10.1128/mBio.01188-15

McDonald C, Jovanović G, Ces O, Buck M. Membrane Stored Curvature Elastic Stress Modulates Recruitment of Maintenance Proteins PspA and Vipp1. in MBIO. 2015;6(5).
doi:10.1128/mBio.01188-15 .

McDonald, Christopher, Jovanović, Goran, Ces, Oscar, Buck, Martin, "Membrane Stored Curvature Elastic Stress Modulates Recruitment of Maintenance Proteins PspA and Vipp1" in MBIO, 6, no. 5 (2015),
https://doi.org/10.1128/mBio.01188-15 . .

TY  - JOUR
AU  - Jovanović, Goran
AU  - Mehta, Parul
AU  - McDonald, Christopher
AU  - Davidson, Anthony C.
AU  - Uzdavinys, Povilas
AU  - Ying, Liming
AU  - Buck, Martin
PY  - 2014
UR  - https://imagine.imgge.bg.ac.rs/handle/123456789/782
AB  - The phage shock protein (Psp) systems found in bacteria, archaea and higher plants respond to extracytoplasmic stresses that damage the cytoplasmic membrane and enable cells to repair their membranes. The conserved membrane-associated effector protein PspA has four a-helical domains (HD1- HD4) and helps to repair the membrane as a high-order oligomer. In enterobacteria, under non-stress conditions, PspA as a low-order assembly directly inhibits its cognate transcription activator PspF. Here we show that N-terminal amphipathic helices ahA and ahB in PspA HD1 are functional determinants involved in negative gene control and stress signal perception and its transduction via interactions with the PspBC membrane stress sensors and the inner membrane (IM). The amphipathic helices enable PspA to switch from a low-order gene regulator into an IM-bound high-order effector complex under membrane stress. Conserved residue proline 25 is involved in sequential use of the amphipathic helices and ahA IM interaction. Single molecule imaging of eGFP-PspA and its amphipathic helices variants in live Escherichia coli cells show distinct spatial and temporal organisations of PspA corresponding to its negative control and effector functions. These findings inform studies on the role of the Psp system in persister cell formation and cell envelope protection in bacterial pathogens and provide a basis for exploring the specialised roles of PspA homologues such as YjfJ, LiaH and Vipp1.
PB  - Academic Press Ltd- Elsevier Science Ltd, London
T2  - Journal of Molecular Biology
T1  - The N-Terminal Amphipathic Helices Determine Regulatory and Effector Functions of Phage Shock Protein A (PspA) in Escherichia coli
EP  - 1511
IS  - 7
SP  - 1498
VL  - 426
DO  - 10.1016/j.jmb.2013.12.016
ER  - 

@article{
author = "Jovanović, Goran and Mehta, Parul and McDonald, Christopher and Davidson, Anthony C. and Uzdavinys, Povilas and Ying, Liming and Buck, Martin",
year = "2014",
abstract = "The phage shock protein (Psp) systems found in bacteria, archaea and higher plants respond to extracytoplasmic stresses that damage the cytoplasmic membrane and enable cells to repair their membranes. The conserved membrane-associated effector protein PspA has four a-helical domains (HD1- HD4) and helps to repair the membrane as a high-order oligomer. In enterobacteria, under non-stress conditions, PspA as a low-order assembly directly inhibits its cognate transcription activator PspF. Here we show that N-terminal amphipathic helices ahA and ahB in PspA HD1 are functional determinants involved in negative gene control and stress signal perception and its transduction via interactions with the PspBC membrane stress sensors and the inner membrane (IM). The amphipathic helices enable PspA to switch from a low-order gene regulator into an IM-bound high-order effector complex under membrane stress. Conserved residue proline 25 is involved in sequential use of the amphipathic helices and ahA IM interaction. Single molecule imaging of eGFP-PspA and its amphipathic helices variants in live Escherichia coli cells show distinct spatial and temporal organisations of PspA corresponding to its negative control and effector functions. These findings inform studies on the role of the Psp system in persister cell formation and cell envelope protection in bacterial pathogens and provide a basis for exploring the specialised roles of PspA homologues such as YjfJ, LiaH and Vipp1.",
publisher = "Academic Press Ltd- Elsevier Science Ltd, London",
journal = "Journal of Molecular Biology",
title = "The N-Terminal Amphipathic Helices Determine Regulatory and Effector Functions of Phage Shock Protein A (PspA) in Escherichia coli",
pages = "1511-1498",
number = "7",
volume = "426",
doi = "10.1016/j.jmb.2013.12.016"
}

Jovanović, G., Mehta, P., McDonald, C., Davidson, A. C., Uzdavinys, P., Ying, L.,& Buck, M.. (2014). The N-Terminal Amphipathic Helices Determine Regulatory and Effector Functions of Phage Shock Protein A (PspA) in Escherichia coli. in Journal of Molecular Biology
Academic Press Ltd- Elsevier Science Ltd, London., 426(7), 1498-1511.
https://doi.org/10.1016/j.jmb.2013.12.016

Jovanović G, Mehta P, McDonald C, Davidson AC, Uzdavinys P, Ying L, Buck M. The N-Terminal Amphipathic Helices Determine Regulatory and Effector Functions of Phage Shock Protein A (PspA) in Escherichia coli. in Journal of Molecular Biology. 2014;426(7):1498-1511.
doi:10.1016/j.jmb.2013.12.016 .

Jovanović, Goran, Mehta, Parul, McDonald, Christopher, Davidson, Anthony C., Uzdavinys, Povilas, Ying, Liming, Buck, Martin, "The N-Terminal Amphipathic Helices Determine Regulatory and Effector Functions of Phage Shock Protein A (PspA) in Escherichia coli" in Journal of Molecular Biology, 426, no. 7 (2014):1498-1511,
https://doi.org/10.1016/j.jmb.2013.12.016 . .