scholarly journals Stress-Responsive Periplasmic Chaperones in Bacteria

2021 ◽  
Vol 8 ◽  
Author(s):  
Hyunhee Kim ◽  
Kevin Wu ◽  
Changhan Lee
Keyword(s):  
Outer Membrane ◽  
Protein Unfolding ◽  
Protein Quality ◽  
Environmental Changes ◽  
Outer Membrane Proteins ◽  
Acid Stress ◽  
Bacterial Survival ◽  
Wide Range ◽  
Periplasmic Proteins ◽  
Periplasmic Chaperones

Periplasmic proteins are involved in a wide range of bacterial functions, including motility, biofilm formation, sensing environmental cues, and small-molecule transport. In addition, a wide range of outer membrane proteins and proteins that are secreted into the media must travel through the periplasm to reach their final destinations. Since the porous outer membrane allows for the free diffusion of small molecules, periplasmic proteins and those that travel through this compartment are more vulnerable to external environmental changes, including those that result in protein unfolding, than cytoplasmic proteins are. To enable bacterial survival under various stress conditions, a robust protein quality control system is required in the periplasm. In this review, we focus on several periplasmic chaperones that are stress responsive, including Spy, which responds to envelope-stress, DegP, which responds to temperature to modulate chaperone/protease activity, HdeA and HdeB, which respond to acid stress, and UgpB, which functions as a bile-responsive chaperone.

Cell envelope proteases and peptidases of Pseudomonas aeruginosa: multiple roles, multiple mechanisms

2020 ◽  
Vol 44 (6) ◽  
pp. 857-873
Author(s):  
Astra Heywood ◽  
Iain L Lamont
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Outer Membrane ◽  
Protein Quality ◽  
Environmental Changes ◽  
Cell Envelope ◽  
Opportunistic Pathogen ◽  
Multiple Roles ◽  
Current State ◽  
Wide Range ◽  
Membrane Cell

ABSTRACT Pseudomonas aeruginosa is a Gram-negative bacterium that is commonly isolated from damp environments. It is also a major opportunistic pathogen, causing a wide range of problematic infections. The cell envelope of P. aeruginosa, comprising the cytoplasmic membrane, periplasmic space, peptidoglycan layer and outer membrane, is critical to the bacteria's ability to adapt and thrive in a wide range of environments. Over 40 proteases and peptidases are located in the P. aeruginosa cell envelope. These enzymes play many crucial roles. They are required for protein secretion out of the cytoplasm to the periplasm, outer membrane, cell surface or the environment; for protein quality control and removal of misfolded proteins; for controlling gene expression, allowing adaptation to environmental changes; for modification and remodelling of peptidoglycan; and for metabolism of small molecules. The key roles of cell envelope proteases in ensuring normal cell functioning have prompted the development of inhibitors targeting some of these enzymes as potential new anti-Pseudomonas therapies. In this review, we summarise the current state of knowledge across the breadth of P. aeruginosa cell envelope proteases and peptidases, with an emphasis on recent findings, and highlight likely future directions in their study.

scholarly journals Periplasmic Chaperones Play Hot Potato With Unfolded Outer Membrane Proteins

2017 ◽  
Vol 31 (S1) ◽  
Author(s):  
Karen G Fleming ◽  
Shawn M Costello ◽  
Ashlee M Plummer ◽  
Patrick J Fleming
Keyword(s):  
Membrane Proteins ◽  
Outer Membrane ◽  
Outer Membrane Proteins ◽  
Periplasmic Chaperones

Periplasmic quality control in biogenesis of outer membrane proteins

2015 ◽  
Vol 43 (2) ◽  
pp. 133-138 ◽  
Author(s):  
Zhi Xin Lyu ◽  
Xin Sheng Zhao
Keyword(s):  
Quality Control ◽  
Membrane Proteins ◽  
Outer Membrane ◽  
Outer Membrane Proteins ◽  
Diverse Range ◽  
Multifunctional Protein ◽  
Proposed Model ◽  
Periplasmic Proteins ◽  
Basic Functions ◽  
Biochemical Analyses

The β-barrel outer membrane proteins (OMPs) are integral membrane proteins that reside in the outer membrane of Gram-negative bacteria and perform a diverse range of biological functions. Synthesized in the cytoplasm, OMPs must be transported across the inner membrane and through the periplasmic space before they are assembled in the outer membrane. In Escherichia coli, Skp, SurA and DegP are the most prominent factors identified to guide OMPs across the periplasm and to play the role of quality control. Although extensive genetic and biochemical analyses have revealed many basic functions of these periplasmic proteins, the mechanism of their collaboration in assisting the folding and insertion of OMPs is much less understood. Recently, biophysical approaches have shed light on the identification of the intricate network. In the present review, we summarize recent advances in the characterization of these key factors, with a special emphasis on the multifunctional protein DegP. In addition, we present our proposed model on the periplasmic quality control in biogenesis of OMPs.

scholarly journals Classifying β-Barrel Assembly Substrates by Manipulating Essential Bam Complex Members

2016 ◽  
Vol 198 (14) ◽  
pp. 1984-1992 ◽  
Author(s):  
Tara F. Mahoney ◽  
Dante P. Ricci ◽  
Thomas J. Silhavy
Keyword(s):  
Escherichia Coli ◽  
Outer Membrane ◽  
Mechanistic Model ◽  
Outer Membrane Proteins ◽  
Permeability Barrier ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Content Type ◽  
Bam Complex ◽  
Periplasmic Chaperones

ABSTRACTThe biogenesis of the outer membrane (OM) ofEscherichia coliis a conserved and vital process. The assembly of integral β-barrel outer membrane proteins (OMPs), which represent a major component of the OM, depends on periplasmic chaperones and the heteropentameric β-barrel assembly machine (Bam complex) in the OM. However, not all OMPs are affected by null mutations in the same chaperones or nonessential Bam complex members, suggesting there are categories of substrates with divergent requirements for efficient assembly. We have previously demonstrated two classes of substrates, one comprising large, low-abundance, and difficult-to-assemble substrates that are heavily dependent on SurA and also Skp and FkpA, and the other comprising relatively simple and abundant substrates that are not as dependent on SurA but are strongly dependent on BamB for assembly. Here, we describe novel mutations inbamDthat lower levels of BamD 10-fold and >25-fold without altering the sequence of the mature protein. We utilized these mutations, as well as a previously characterized mutation that lowers wild-type BamA levels, to reveal a third class of substrates. These mutations preferentially cause a marked decrease in the levels of multimeric proteins. This susceptibility of multimers to lowered quantities of Bam machines in the cell may indicate that multiple Bam complexes are needed to efficiently assemble multimeric proteins into the OM.IMPORTANCEThe outer membrane (OM) of Gram-negative bacteria, such asEscherichia coli, serves as a selective permeability barrier that prevents the uptake of toxic molecules and antibiotics. Integral β-barrel proteins (OMPs) are assembled by the β-barrel assembly machine (Bam), components of which are conserved in mitochondria, chloroplasts, and all Gram-negative bacteria, including many clinically relevant pathogenic species. Bam is essential for OM biogenesis and accommodates a diverse array of client proteins; however, a mechanistic model that accounts for the selectivity and broad substrate range of Bam is lacking. Here, we show that the assembly of multimeric OMPs is more strongly affected than that of monomeric OMPs when essential Bam complex components are limiting, suggesting that multiple Bam complexes are needed to assemble multimeric proteins.

scholarly journals Characterization of the Outer Membrane Proteome of Leptospira interrogans Expressed during Acute Lethal Infection

2006 ◽  
Vol 75 (2) ◽  
pp. 766-773 ◽  
Author(s):  
Jarlath E. Nally ◽  
Julian P. Whitelegge ◽  
Sara Bassilian ◽  
David R. Blanco ◽  
Michael A. Lovett
Keyword(s):  
Membrane Proteins ◽  
Outer Membrane ◽  
Disease Transmission ◽  
Guinea Pigs ◽  
Outer Membrane Proteins ◽  
Acute Infection ◽  
Hydrophobic Membrane ◽  
Lethal Infection ◽  
Wide Range

ABSTRACT Pathogenic Leptospira species adapt to a wide range of environmental conditions during disease transmission and infection. While the proteome of in vitro cultivated Leptospira has been characterized in several studies to date, relatively little is known of the proteome as expressed by Leptospira during disease processes. Isolates of Leptospira obtained from patients suffering the severe pulmonary form of leptospirosis cause acute lethal infection in guinea pigs and chronic asymptomatic infection in rats. Recent studies have demonstrated that protein and lipopolysaccharide constituents of Leptospira recovered from acutely infected guinea pig tissue differ from that of Leptospira in chronically infected rat tissue and in vitro cultivated Leptospira (J. E. Nally, E. Chow, M. C. Fishbein, D. R. Blanco, and M. A. Lovett, Infect. Immun. 73:3251-3260, 2005). In the current study, the proteome of Leptospira expressed during disease processes was characterized relative to that of in vitro cultivated Leptospira (IVCL) after enrichment for hydrophobic membrane proteins with Triton X-114. Protein samples were separated by two-dimensional gel electrophoresis, and antigens expressed during infection were identified by immunoblotting with monospecific antiserum and convalescent rat serum in addition to mass spectrometry. Results suggest a significant increase in the expression of the outer membrane protein Loa22 during acute infection of guinea pigs relative to other outer membrane proteins, whose expression is generally diminished relative to expression in IVCL. Significant amounts of LipL32 are also expressed by Leptospira during acute infection of guinea pigs.

scholarly journals Contribution of the Clp Protease to Bacterial Survival and Mitochondrial Homoeostasis

2021 ◽  
pp. 1-20
Author(s):  
Astrid Illigmann ◽  
Yvonne Thoma ◽  
Stefan Pan ◽  
Laura Reinhardt ◽  
Heike Brötz-Oesterhelt
Keyword(s):  
Quality Control ◽  
Regulatory Networks ◽  
Protein Quality ◽  
Environmental Changes ◽  
Protein Quality Control ◽  
Adaptor Proteins ◽  
Degradation Process ◽  
Eukaryotic Cells ◽  
Bacterial Survival ◽  
Clp Protease

Fast adaptation to environmental changes ensures bacterial survival, and proteolysis represents a key cellular process in adaptation. The Clp protease system is a multi-component machinery responsible for protein homoeostasis, protein quality control, and targeted proteolysis of transcriptional regulators in prokaryotic cells and prokaryote-derived organelles of eukaryotic cells. A functional Clp protease complex consists of the tetradecameric proteolytic core ClpP and a hexameric ATP-consuming Clp-ATPase, several of which can associate with the same proteolytic core. Clp-ATPases confer substrate specificity by recognising specific degradation tags, and further selectivity is conferred by adaptor proteins, together allowing for a fine-tuned degradation process embedded in elaborate regulatory networks. This review focuses on the contribution of the Clp protease system to prokaryotic survival and summarises the current state of knowledge for exemplary bacteria in an increasing degree of interaction with eukaryotic cells. Starting from free-living bacteria as exemplified by a non-pathogenic and a pathogenic member of the Firmicutes, i.e., <i>Bacillus subtilis</i> and <i>Staphylococcus aureus</i>, respectively, we turn our attention to facultative and obligate intracellular bacterial pathogens, i.e., <i>Mycobacterium tuberculosis, Listeria monocytogenes,</i> and <i>Chlamydia trachomatis</i>, and conclude with mitochondria. Under stress conditions, the Clp protease system exerts its pivotal role in the degradation of damaged proteins and controls the timing and extent of the heat-shock response by regulatory proteolysis. Key regulators of developmental programmes like natural competence, motility, and sporulation are also under Clp proteolytic control. In many pathogenic species, the Clp system is required for the expression of virulence factors and essential for colonising the host. In accordance with its evolutionary origin, the human mitochondrial Clp protease strongly resembles its bacterial counterparts, taking a central role in protein quality control and homoeostasis, energy metabolism, and apoptosis in eukaryotic cells, and several cancer cell types depend on it for proliferation.

scholarly journals Identification of Immunogenic Linear B-Cell Epitopes in C. burnetii Outer Membrane Proteins Using Immunoinformatics Approaches Reveals Potential Targets of Persistent Infections

Pathogens ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 1250
Author(s):  
Sílvia da Silva Fontes ◽  
Fernanda de Moraes Maia ◽  
Laura Santa’Anna Ataides ◽  
Fernando Paiva Conte ◽  
Josué da Costa Lima-Junior ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
B Cell ◽  
Outer Membrane ◽  
Q Fever ◽  
Outer Membrane Proteins ◽  
Humoral Response ◽  
Neglected Diseases ◽  
B Cell Epitopes ◽  
Wide Range ◽  
Linear B

Coxiella burnetii is a global, highly infectious intracellular bacterium, able to infect a wide range of hosts and to persist for months in the environment. It is the etiological agent of Q fever—a zoonosis of global priority. Currently, there are no national surveillance data on C. burnetii’s seroprevalence for any South American country, reinforcing the necessity of developing novel and inexpensive serological tools to monitor the prevalence of infections among humans and animals—especially cattle, goats, and sheep. In this study, we used immunoinformatics and computational biology tools to predict specific linear B-cell epitopes in three C. burnetii outer membrane proteins: OMP-H (CBU_0612), Com-1 (CBU_1910), and OMP-P1 (CBU_0311). Furthermore, predicted epitopes were tested by ELISA, as synthetic peptides, against samples of patients reactive to C. burnetii in indirect immunofluorescence assay, in order to evaluate their natural immunogenicity. In this way, two linear B-cell epitopes were identified in each studied protein (OMP-H(51–59), OMP-H(91–106), Com-1(57–76), Com-1(191–206), OMP-P1(197–209), and OMP-P1(215–227)); all of them were confirmed as naturally immunogenic by the presence of specific antibodies in 77% of studied patients against at least one of the identified epitopes. Remarkably, a higher frequency of endocarditis cases was observed among patients who presented an intense humoral response to OMP-H and Com-1 epitopes. These data confirm that immunoinformatics applied to the identification of specific B-cell epitopes can be an effective strategy to improve and accelerate the development of surveillance tools against neglected diseases.

scholarly journals Differential Effects of yfgL Mutation on Escherichia coli Outer Membrane Proteins and Lipopolysaccharide

2006 ◽  
Vol 188 (20) ◽  
pp. 7186-7194 ◽  
Author(s):  
Emily S. Charlson ◽  
John N. Werner ◽  
Rajeev Misra
Keyword(s):  
Escherichia Coli ◽  
Membrane Proteins ◽  
Outer Membrane ◽  
Outer Membrane Proteins ◽  
Protein Assembly ◽  
Synthetic Lethal ◽  
Negative Effect ◽  
Periplasmic Chaperones ◽  
Sigma E ◽  
Assembly Pathways

ABSTRACT YfgL together with NlpB, YfiO, and YaeT form a protein complex to facilitate the insertion of proteins into the outer membrane of Escherichia coli. Without YfgL, the levels of OmpA, OmpF, and LamB are significantly reduced, while OmpC levels are slightly reduced. In contrast, the level of TolC significantly increases in a yfgL mutant. When cells are depleted of YaeT or YfiO, levels of all outer membrane proteins examined, including OmpC and TolC, are severely reduced. Thus, while the assembly pathways of various nonlipoprotein outer membrane proteins may vary through the step involving YfgL, all assembly pathways in Escherichia coli converge at the step involving the YaeT/YfiO complex. The negative effect of yfgL mutation on outer membrane proteins may in part be due to elevated sigma E activity, which has been shown to downregulate the synthesis of various outer membrane proteins while upregulating the synthesis of periplasmic chaperones, foldases, and lipopolysaccharide. The data presented here suggest that the yfgL effect on outer membrane proteins also stems from a defective assembly apparatus, leading to aberrant outer membrane protein assembly, except for TolC, which assembles independent of YfgL. Consistent with this view, the simultaneous absence of YfgL and the major periplasmic protease DegP confers a synthetic lethal phenotype, presumably due to the toxic accumulation of unfolded outer membrane proteins. The results support the hypothesis that TolC and major outer membrane proteins compete for the YaeT/YfiO complex, since mutations that adversely affect synthesis or assembly of major outer membrane proteins lead to elevated TolC levels.

scholarly journals VirK Is a Periplasmic Protein Required for Efficient Secretion of Plasmid-Encoded Toxin from Enteroaggregative Escherichia coli

2012 ◽  
Vol 80 (7) ◽  
pp. 2276-2285 ◽  
Author(s):  
Gabriela Tapia-Pastrana ◽  
Lucia Chavez-Dueñas ◽  
Humberto Lanz-Mendoza ◽  
Ken Teter ◽  
Fernando Navarro-García
Keyword(s):  
Escherichia Coli ◽  
Outer Membrane ◽  
Cytotoxic Effect ◽  
Periplasmic Protein ◽  
Passenger Domain ◽  
Content Type ◽  
Periplasmic Proteins ◽  
Porin Proteins ◽  
Periplasmic Chaperones ◽  
Domain Insertion

ABSTRACTDespite the autotransporter (AT) moniker, AT secretion appears to involve the function of periplasmic chaperones. We identified four periplasmic proteins that specifically bound to plasmid-encoded toxin (Pet), an AT produced by enteroaggregativeEscherichia coli(EAEC). These proteins include the 17-kDa Skp chaperone and the 37-kDa VirK protein. We found that thevirKgene is present in differentEnterobacteriaceae. VirK bound to misfolded conformations of the Pet passenger domain, but it did not bind to the folded passenger domain or to the β domain of Pet. Assays with an EAECΔvirKmutant and its complemented version showed that, in the absence of VirK, Pet was not secreted but was instead retained in the periplasm as proteolytic fragments. In contrast, Pet was secreted from a Δskpmutant. VirK was not required for the insertion of porin proteins into the outer membrane but assisted with insertion of the Pet β domain into the outer membrane. Loss of VirK function blocked the EAEC-mediated cytotoxic effect against HEp-2 cells. Thus, VirK facilitates the secretion of the AT Pet by maintaining the passenger domain in a conformation that both avoids periplasmic proteolysis and facilitates β-domain insertion into the outer membrane.

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