Membrane Stored Curvature Elastic Stress Modulates Recruitment of Maintenance Proteins PspA and Vipp1

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

Effects of social defeat on iK-ba inflammatory signaling in male c57BL/6J

An estimated 30 million people in the United States have been diagnosed with mood and anxiety disorders. Unfortunately, many of these patients do not adequately respond to current pharmacotherapies, so developing new drugs and strategies to treat such disorders is critically important. There are only a few drugs on the market that target neuroinflammation. Thus, it's critical that we identify anti-inflammatory agents that effectively reduce neuroinflammatory responses, hereby expanding or augmenting available options for treating neurological disorders. Previous work has shown that the derivative of naltrexone, B-funaltrexamine (B-FNA), inhibits inflammatory signaling in human astrocytes in reduced expression of proinflammatory chemokines. IKBa is one of the specific signaling proteins in the inflammation pathway

Structure and function of PspA and Vipp1 N-terminal peptides: Insights into the membrane stress sensing and mitigation

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

Virus-like particle vaccines against BK and JC polyomaviruses

Nearly all healthy adults are asymptomatically infected with human polyomaviruses. In immunosuppressed individuals, the infection can reactivate and cause disease. BK polyomavirus (BKV) frequently damages transplanted kidneys and causes severe bladder disease in bone marrow transplant patients. JC polyomavirus (JCV) causes a lethal brain disease, PML, in individuals on various immunosuppressive therapies. PML also affects immunodeficient individuals, including AIDS patients. The outer capsid proteins of polyomaviruses are structurally similar to the capsids of human papillomaviruses (HPVs). Building on the success of the NCI’s HPV virus-like particle (VLP) vaccine technologies, we have developed VLP vaccines targeting BKV and JCV. Preclinical testing in a monkey model indicates that the BKV and JCV VLP vaccines share the HPV vaccines’ exceptionally potent immunogenicity. Given our knowledge of the role that antibodies play in ameliorating polyomavirus pathologies, the new VLP vaccines are likely to protect at-risk patients against the development of BKV-induced urinary tract disease and JCV-induced brain disease. Each year, roughly 30,000 Americans join wait-lists for kidney transplantation. Additionally, roughly 300,000 Americans per year are diagnosed with diseases that might be treated with bone marrow transplantation. Emerging evidence indicates that antibody-producing plasma cells elicited by the BKV vaccine will persist after bone marrow transplantation and the vaccine should thus provide protection against post-transplant hemorrhagic cystitis. The highly effective multiple sclerosis therapy Tysabri (natalizumab) is associated with up to 2% risk of PML side effects. Rituxan (rituximab), which is used for treatment of rheumatoid arthritis and certain types of lymphoma, carries a black box warning for PML and a dozen additional immunosuppressive therapies are also known or suspected to have PML side effects. The JCV vaccine should be a useful preventive adjunct for these popular immunotherapies. Since there are currently no effective treatments for BKV or JCV diseases, the candidate vaccines seem likely to qualify for FDA’s Accelerated Approval Program. The NCI is currently seeking industry partners

Transcription Regulation and Membrane Stress Management in Enterobacterial Pathogens

Transcription regulation in a temporal and conditional manner underpins the lifecycle of enterobacterial pathogens. Upon exposure to a wide array of environmental cues, these pathogens modulate their gene expression via the RNA polymerase and associated sigma factors. Different sigma factors, either involved in general 'house-keeping' or specific responses, guide the RNA polymerase to their cognate promoter DNAs. The major alternative sigma54 factor when activated helps pathogens manage stresses and proliferate in their ecological niches. In this chapter, we review the function and regulation of the sigma54-dependent Phage shock protein (Psp) system-a major stress response when Gram-negative pathogens encounter damages to their inner membranes. We discuss the recent development on mechanisms of gene regulation, signal transduction and stress mitigation in light of different biophysical and biochemical approaches.This is the peer reviewed version of the paper: Zhang, N., Jovanovic, G., McDonald, C., Ces, O., Zhang, X., & Buck, M. (2016). Transcription Regulation and Membrane Stress Management in Enterobacterial Pathogens. У M. C. Leake (Ур.), Biophysics of Infection (стр. 207–230). Springer International Publishing. [https://doi.org/10.1007/978-3-319-32189-9_13

Characterization of the binding and neutralizing properties of monoclonal antibodies against JCV

Antibody-based immunity to JC polyomavirus (JCV) is not well understood and monoclonal Antibodies (mAbs) that functionally neutralize the infectivity of JCV have not been documented. (1). Virus Like Particles (VLP)-based ELISAs can detect JCV-binding antibodies that do not necessarily neutralize the infectivity of JCV. Therefore, functional neutralization-based serology will be needed to validate candidate JCV VLP vaccines and therapeutic McAbs. (2). The neutralizing activity of McAbs can be specific for particular genotypes and clinical strains. Hence, VLPs from multiple genotypes may be needed to formulate a vaccine that could protect against diverse JCV strains circulating in patients with progressive multifocal encephalopathy (PML)

Expression of the small T antigen of Lymphotropic Papovavirus is sufficient to transform primary mouse embryo fibroblasts

AbstractPolyomaviruses induce cell proliferation and transformation through different oncoproteins encoded within the early region (ER): large T antigen (LT), small T antigen (sT) and, in some cases, additional components. Each virus utilizes different mechanisms to achieve transformation. For instance, the LTs of Simian virus 40 (SV40), BK and/or JC virus can induce transformation; but Merkel Cell Polyomavirus (MCPyV) requires expression of sT. Lymphotropic Papovavirus (LPV) is closely related to Human Polyomavirus 9 (HuPyV9) and, under similar conditions, mice expressing LPV.ER exhibit higher rates of tumor formation than mice expressing SV40.ER. We have investigated the contributions of individual LPV.ER components to cell transformation. In contrast to SV40, LPV.ER transforms mouse embryonic fibroblasts (MEFs), but expression of LPV LT is insufficient to transform MEFs. Furthermore, LPV sT induces immortalization and transformation of MEFs. Thus, in the case of LPV, sT is the main mediator of oncogenesis