scholarly journals Novel Outer Membrane Protein Involved in Cellulose and Cellooligosaccharide Degradation by Cytophaga hutchinsonii

2014 ◽  
Vol 80 (15) ◽  
pp. 4511-4518 ◽  
Author(s):  
Xiaofei Ji ◽  
Ying Wang ◽  
Cong Zhang ◽  
Xinfeng Bai ◽  
Weican Zhang ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Cell Surface ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Cellulose Degradation ◽  
Outer Membrane Proteins ◽  
Cellulolytic Enzymes ◽  
Content Type ◽  
Cytophaga Hutchinsonii ◽  
Glucosidase Activity

ABSTRACTCytophaga hutchinsoniiis an aerobic cellulolytic soil bacterium which was reported to use a novel contact-dependent strategy to degrade cellulose. It was speculated that cellooligosaccharides were transported into the periplasm for further digestion. In this study, we reported that most of the endoglucanase and β-glucosidase activity was distributed on the cell surface ofC. hutchinsonii. Cellobiose and part of the cellulose could be hydrolyzed to glucose on the cell surface. However, the cell surface cellulolytic enzymes were not sufficient for cellulose degradation byC. hutchinsonii. An outer membrane protein, CHU_1277, was disrupted by insertional mutation. Although the mutant maintained the same endoglucanase activity and most of the β-glucosidase activity, it failed to digest cellulose, and its cellooligosaccharide utilization ability was significantly reduced, suggesting that CHU_1277 was essential for cellulose degradation and played an important role in cellooligosaccharide utilization. Further study of cellobiose hydrolytic ability of the mutant on the enzymatic level showed that the β-glucosidase activity in the outer membrane of the mutant was not changed. It revealed that CHU_1277 played an important role in assisting cell surface β-glucosidase to exhibit its activity sufficiently. Studies on the outer membrane proteins involved in cellulose and cellooligosaccharide utilization could shed light on the mechanism of cellulose degradation byC. hutchinsonii.

scholarly journals An Outer Membrane Protein Involved in the Uptake of Glucose Is Essential for Cytophaga hutchinsonii Cellulose Utilization

2016 ◽  
Vol 82 (6) ◽  
pp. 1933-1944 ◽  
Author(s):  
Hong Zhou ◽  
Xia Wang ◽  
Tengteng Yang ◽  
Weixin Zhang ◽  
Guanjun Chen ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Cellulose Degradation ◽  
Expression Profiles ◽  
Transcriptional Profiling ◽  
Hydrolysis Product ◽  
Transcriptional Responses ◽  
Content Type ◽  
Cytophaga Hutchinsonii

ABSTRACTCytophaga hutchinsoniispecializes in cellulose digestion by employing a collection of novel cell-associated proteins. Here, we identified a novel gene locus, CHU_1276, that is essential forC. hutchinsoniicellulose utilization. Disruption of CHU_1276 inC. hutchinsoniiresulted in complete deficiency in cellulose degradation, as well as compromised assimilation of cellobiose or glucose at a low concentration. Further analysis showed that CHU_1276 was an outer membrane protein that could be induced by cellulose and low concentrations of glucose. Transcriptional profiling revealed that CHU_1276 exerted a profound effect on the genome-wide response to both glucose and Avicel and that the mutant lacking CHU_1276 displayed expression profiles very different from those of the wild-type strain under different culture conditions. Specifically, comparison of their transcriptional responses to cellulose led to the identification of a gene set potentially regulated by CHU_1276. These results suggest that CHU_1276 plays an essential role in cellulose utilization, probably by coordinating the extracellular hydrolysis of cellulose substrate with the intracellular uptake of the hydrolysis product inC. hutchinsonii.

scholarly journals An Extracytoplasmic Function Sigma Factor Controls Cellulose Utilization by Regulating the Expression of an Outer Membrane Protein inCytophaga hutchinsonii

2018 ◽  
Vol 85 (5) ◽  
Author(s):  
Xia Wang ◽  
Weixin Zhang ◽  
Hong Zhou ◽  
Guanjun Chen ◽  
Weifeng Liu
Keyword(s):  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Regulatory Mechanism ◽  
Outer Membrane Proteins ◽  
Cellulolytic Bacterium ◽  
Content Type ◽  
Cytophaga Hutchinsonii ◽  
Σ Factor ◽  
The Common

ABSTRACTThe common soil cellulolytic bacterium known asCytophaga hutchinsoniimakes use of a unique but poorly understood strategy in order to utilize cellulose. While several genes have been identified as being an active part of the utilization of cellulose, the mechanism(s) by whichC. hutchinsoniiboth (i) senses its environment and (ii) regulates the expression of those genes are not as yet known. In this study, we identified and characterized the geneCHU_3097encoding an extracytoplasmic function (ECF) σ factor (σcel1), the disruption of which compromisedC. hutchinsoniicellulose assimilation to a large degree. The σcel1and its putative partner anti-σcel1, encoded by theCHU_3096gene found immediately downstream fromCHU_3097, copurifiedin vitro. The σcel1was discovered to be associated with inner membrane when cells were cultured on glucose and yet was partially released from the membrane in response to cellulose. This release was found to occur on glucose when the anti-σcel1was absent. Transcriptome analyses found a σcel1-regulated, cellulose-responsive gene regulon, within which an outer membrane protein encoding the geneCHU_1276, essential for cellulose utilization, was discovered to be significantly downregulated byCHU_3097disruption. The expression of CHU_1276 almost fully restored cellulose utilization to theCHU_3097mutant, demonstrating that CHU_1276 represents a critical regulatory target of σcel1. In this way, our study provided insights into the role of an ECF σ factor in coordinating the cellulolytic response ofC. hutchinsonii.IMPORTANCEThe common cellulolytic bacteriumCytophaga hutchinsoniiuses a unique but poorly understood strategy in order to make use of cellulose. Throughout the process of cellulosic biomass breakdown, outer membrane proteins are thought to play key roles; this is evidenced by CHU_1276, which is required for the utilization of cellulose. However, the regulatory mechanism of its expression is not yet known. We found and characterized an extracytoplasmic function σ factor that is involved in coordinating the cellulolytic response ofC. hutchinsoniiby directly regulating the expression ofCHU_1276. This study makes a contribution to our understanding of the regulatory mechanism used byC. hutchinsoniiin order to adjust its genetic programs and so deal with novel environmental cues.

scholarly journals A Disulfide Oxidoreductase (CHU_1165) Is Essential for Cellulose Degradation by Affecting Outer Membrane Proteins in Cytophaga hutchinsonii

2020 ◽  
Vol 86 (8) ◽  
Author(s):  
Dong Zhao ◽  
Ying Wang ◽  
Sen Wang ◽  
Weican Zhang ◽  
Qingsheng Qi ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Outer Membrane ◽  
Disulfide Bond ◽  
Cellulose Degradation ◽  
Outer Membrane Proteins ◽  
Hypothetical Protein ◽  
Pleiotropic Effect ◽  
Content Type ◽  
Cytophaga Hutchinsonii ◽  
Disulfide Oxidoreductase

ABSTRACT Cytophaga hutchinsonii cells can bind to the surface of insoluble cellulose and degrade it by utilizing a novel cell contact-dependent mechanism, in which the outer membrane proteins may play important roles. In this study, the deletion of a gene locus, chu_1165, which encodes a hypothetical protein with 32% identity with TlpB, a disulfide oxidoreductase in Flavobacterium psychrophilum, caused a complete cellulolytic defect in C. hutchinsonii. Further study showed that cells of the Δ1165 strain could not bind to cellulose, and the levels of many outer membrane proteins that can bind to cellulose were significantly decreased. The N-terminal region of CHU_1165 is anchored to the cytoplasmic membrane with five predicted transmembrane helices, and the C-terminal region is predicted to stretch to the periplasm and has a similar thioredoxin (Trx) fold containing a Cys-X-X-Cys motif that is conserved in disulfide oxidoreductases. Recombinant CHU_1165His containing the Cys-X-X-Cys motif was able to reduce the disulfide bonds of insulin in vitro. Site-directed mutation showed that the cysteines in the Cys-X-X-Cys motif and at residues 106 and 108 were indispensable for the function of CHU_1165. Western blotting showed that CHU_1165 was in an oxidized state in vivo, suggesting that it may act as an oxidase to catalyze disulfide bond formation. However, many of the decreased outer membrane proteins that were essential for cellulose degradation contained no or one cysteine, and mutation of the cysteine in these proteins did not affect cellulose degradation, indicating that CHU_1165 may have an indirect or pleiotropic effect on the function of these outer membrane proteins. IMPORTANCE Cytophaga hutchinsonii can rapidly digest cellulose in a contact-dependent manner, in which the outer membrane proteins may play important roles. In this study, a hypothetical protein, CHU_1165, characterized as a disulfide oxidoreductase, is essential for cellulose degradation by affecting the cellulose binding ability of many outer membrane proteins in C. hutchinsonii. Disulfide oxidoreductases are involved in disulfide bond formation. However, our studies show that many of the decreased outer membrane proteins that were essential for cellulose degradation contained no or one cysteine, and mutation of cysteine did not affect their function, indicating that CHU_1165 did not facilitate the formation of a disulfide bond in these proteins. It may have an indirect or pleiotropic effect on the function of these outer membrane proteins. Our study provides an orientation for exploring the proteins that assist in the appropriate conformation of many outer membrane proteins essential for cellulose degradation, which is important for exploring the novel mechanism of cellulose degradation in C. hutchinsonii.

scholarly journals Periplasmic Cytophaga hutchinsonii Endoglucanases Are Required for Use of Crystalline Cellulose as the Sole Source of Carbon and Energy

2016 ◽  
Vol 82 (15) ◽  
pp. 4835-4845 ◽  
Author(s):  
Yongtao Zhu ◽  
Lanlan Han ◽  
Kathleen L. Hefferon ◽  
Nicholas R. Silvaggi ◽  
David B. Wilson ◽  
...  
Keyword(s):  
Cell Surface ◽  
Outer Membrane ◽  
Soluble Sugars ◽  
Surface Proteins ◽  
Cellulolytic Enzymes ◽  
Crystalline Cellulose ◽  
Cell Fractionation ◽  
Unknown Mechanism ◽  
Content Type ◽  
Cytophaga Hutchinsonii

ABSTRACTThe soil bacteriumCytophaga hutchinsoniiactively digests crystalline cellulose by a poorly understood mechanism. Genome analyses identified nine genes predicted to encode endoglucanases with roles in this process. No predicted cellobiohydrolases, which are usually involved in the utilization of crystalline cellulose, were identified. Chromosomal deletions were performed in eight of the endoglucanase-encoding genes:cel5A,cel5B,cel5C,cel9A,cel9B,cel9C,cel9E, andcel9F. Each mutant retained the ability to digest crystalline cellulose, although the deletion ofcel9Ccaused a modest decrease in cellulose utilization. Strains with multiple deletions were constructed to identify the critical cellulases. Cells of a mutant lacking bothcel5Bandcel9Cwere completely deficient in growth on cellulose. Cell fractionation and biochemical analyses indicate that Cel5B and Cel9C are periplasmic nonprocessive endoglucanases. The requirement of periplasmic endoglucanases for cellulose utilization suggests that cellodextrins are transported across the outer membrane during this process. Bioinformatic analyses predict that Cel5A, Cel9A, Cel9B, Cel9D, and Cel9E are secreted across the outer membrane by the type IX secretion system, which has been linked to cellulose utilization. These secreted endoglucanases may perform the initial digestion within amorphous regions on the cellulose fibers, releasing oligomers that are transported into the periplasm for further digestion by Cel5B and Cel9C. The results suggest that both cell surface and periplasmic endoglucanases are required for the growth ofC. hutchinsoniion cellulose and that novel cell surface proteins may solubilize and transport cellodextrins across the outer membrane.IMPORTANCEThe bacteriumCytophaga hutchinsoniidigests crystalline cellulose by an unknown mechanism. It lacks processive cellobiohydrolases that are often involved in cellulose digestion. Critical cellulolytic enzymes were identified by genetic analyses. Intracellular (periplasmic) nonprocessive endoglucanases performed an important role in cellulose utilization. The results suggest a model involving partial digestion at the cell surface, solubilization and uptake of cellodextrins across the outer membrane by an unknown mechanism, and further digestion within the periplasm. The ability to sequester cellodextrins and digest them intracellularly may limit losses of soluble cellobiose to other organisms.C. hutchinsoniiuses an unusual approach to digest cellulose and is a potential source of novel proteins to increase the efficiency of conversion of cellulose into soluble sugars and biofuels.

scholarly journals Phase Variation of PorA, a Major Outer Membrane Protein, Mediates Escape of Bactericidal Antibodies by Neisseria meningitidis

2013 ◽  
Vol 81 (4) ◽  
pp. 1374-1380 ◽  
Author(s):  
Isfahan Tauseef ◽  
Youssif M. Ali ◽  
Christopher D. Bayliss
Keyword(s):  
Membrane Protein ◽  
Neisseria Meningitidis ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Outer Membrane Proteins ◽  
Phase Variation ◽  
Surface Expression ◽  
Content Type ◽  
Repeat Tract ◽  
Fold Reduction

ABSTRACTSeveral outer membrane proteins ofNeisseria meningitidisare subject to phase variation due to alterations in simple sequence repeat tracts. The PorA protein is a major outer membrane protein and a target for protective host immune responses. Phase variation of PorA is mediated by a poly-G repeat tract present within the promoter, leading to alterations in protein expression levels.N. meningitidisstrain 8047 was subjected to serial passage in the presence of P1.2, a PorA-specific bactericidal monoclonal antibody. Rapid development of resistance to bactericidal activity was associated with a switch in the PorA repeat tract from 11G to 10G. Phase variants with a 10G repeat tract exhibited a 2-fold reduction in surface expression of PorA protein. AmutSmutant of strain 8047, with an elevated phase variation rate, exhibited a higher rate of escape and an association of escape with 10G and 9G variants, the latter having a 13-fold reduction in surface expression of PorA. We conclude that graduated reductions in the surface expression of outer membrane proteins mediated by phase variation enable meningococci to escape killingin vitroby bactericidal antibodies. These findings indicate how phase variation could have a major impact on immune escape and host persistence of meningococci.

scholarly journals Evaluation of Protective Potential of Yersinia pestis Outer Membrane Protein Antigens as Possible Candidates for a New-Generation Recombinant Plague Vaccine

2012 ◽  
Vol 20 (2) ◽  
pp. 227-238 ◽  
Author(s):  
Tatiana E. Erova ◽  
Jason A. Rosenzweig ◽  
Jian Sha ◽  
Giovanni Suarez ◽  
Johanna C. Sierra ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Yersinia Pestis ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Outer Membrane Proteins ◽  
Spectrometric Analysis ◽  
Protein Antigens ◽  
Pneumonic Plague ◽  
Content Type ◽  
New Generation

ABSTRACTPlague caused byYersinia pestismanifests itself in bubonic, septicemic, and pneumonic forms. Although the U.S. Food and Drug Administration recently approved levofloxacin, there is no approved human vaccine against plague. The capsular antigen F1 and the low-calcium-response V antigen (LcrV) ofY. pestisrepresent excellent vaccine candidates; however, the inability of the immune responses to F1 and LcrV to provide protection againstY. pestisF1−strains or those which harbor variants of LcrV is a significant concern. Here, we show that the passive transfer of hyperimmune sera from rats infected with the plague bacterium and rescued by levofloxacin protected naive animals against pneumonic plague. Furthermore, 10 to 12 protein bands from wild-type (WT)Y. pestisCO92 reacted with the aforementioned hyperimmune sera upon Western blot analysis. Based on mass spectrometric analysis, four of these proteins were identified as attachment invasion locus (Ail/OmpX), plasminogen-activating protease (Pla), outer membrane protein A (OmpA), and F1. The genes encoding these proteins were cloned, and the recombinant proteins purified fromEscherichia colifor immunization purposes before challenging mice and rats with either the F1−mutant or WT CO92 in bubonic and pneumonic plague models. Although antibodies to Ail and OmpA protected mice against bubonic plague when challenged with the F1−CO92 strain, Pla antibodies were protective against pneumonic plague. In the rat model, antibodies to Ail provided protection only against pneumonic plague after WT CO92 challenge. Together, the addition ofY. pestisouter membrane proteins to a new-generation recombinant vaccine could provide protection against a wide variety ofY. pestisstrains.

scholarly journals Two Protein Lysine Methyltransferases Methylate Outer Membrane Protein B from Rickettsia

2012 ◽  
Vol 194 (23) ◽  
pp. 6410-6418 ◽  
Author(s):  
Amila H. Abeykoon ◽  
Chien-Chung Chao ◽  
Guanghui Wang ◽  
Marjan Gucek ◽  
David C. H. Yang ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Outer Membrane ◽  
Dna Sequences ◽  
Outer Membrane Protein ◽  
Specific Activity ◽  
Outer Membrane Proteins ◽  
Enzymatic System ◽  
Content Type ◽  
Lysine Methyltransferases ◽  
Protein B

ABSTRACTRickettsia prowazekii, the etiologic agent of epidemic typhus, is a potential biological threat agent. Its outer membrane protein B (OmpB) is an immunodominant antigen and plays roles as protective envelope and as adhesins. The observation of the correlation between methylation of lysine residues in rickettsial OmpB and bacterial virulence has suggested the importance of an enzymatic system for the methylation of OmpB. However, no rickettsial lysine methyltransferase has been characterized. Bioinformatic analysis of genomic DNA sequences ofRickettsiaidentified putative lysine methyltransferases. The genes of the potential methyltransferases were synthesized, cloned, and expressed inEscherichia coli, and expressed proteins were purified by nickel-nitrilotriacetic acid (Ni-NTA) affinity chromatography. The methyltransferase activities of the purified proteins were analyzed by methyl incorporation of radioactively labeledS-adenosylmethionine into recombinant fragments of OmpB. Two putative recombinant methyltransferases (rRP789 and rRP027-028) methylated recombinant OmpB fragments. The specific activity of rRP789 is 10- to 30-fold higher than that of rRP027-028. Western blot analysis using specific antibodies against trimethyl lysine showed that both rRP789 and rRP027-028 catalyzed trimethylation of recombinant OmpB fragments. Liquid chromatography-tandem mass spectrometry (LC/MS-MS) analysis showed that rRP789 catalyzed mono-, di-, and trimethylation of lysine, while rRP027-028 catalyzed exclusively trimethylation. To our knowledge, rRP789 and rRP027-028 are the first biochemically characterized lysine methyltransferases of outer membrane proteins from Gram-negative bacteria. The production and characterization of rickettsial lysine methyltransferases provide new tools to investigate the mechanism of methylation of OmpB, effects of methylation on the structure and function of OmpB, and development of methylated OmpB-based diagnostic assays and vaccine candidates.

scholarly journals Anaplasma phagocytophilum Outer Membrane Protein A Interacts with Sialylated Glycoproteins To Promote Infection of Mammalian Host Cells

2012 ◽  
Vol 80 (11) ◽  
pp. 3748-3760 ◽  
Author(s):  
Nore Ojogun ◽  
Amandeep Kahlon ◽  
Stephanie A. Ragland ◽  
Matthew J. Troese ◽  
Juliana E. Mastronunzio ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Anaplasma Phagocytophilum ◽  
Protein A ◽  
Host Cells ◽  
Mammalian Host ◽  
Content Type ◽  
Outer Membrane Protein A ◽  
Sialylated Glycoproteins

ABSTRACTAnaplasma phagocytophilumis the tick-transmitted obligate intracellular bacterium that causes human granulocytic anaplasmosis (HGA).A. phagocytophilumbinding to sialyl Lewis x (sLex) and other sialylated glycans that decorate P selectin glycoprotein 1 (PSGL-1) and other glycoproteins is critical for infection of mammalian host cells. Here, we demonstrate the importance ofA. phagocytophilumouter membrane protein A (OmpA) APH_0338 in infection of mammalian host cells. OmpA is transcriptionally induced during transmission feeding ofA. phagocytophilum-infected ticks on mice and is upregulated during invasion of HL-60 cells. OmpA is presented on the pathogen's surface. Sera from HGA patients and experimentally infected mice recognize recombinant OmpA. Pretreatment ofA. phagocytophilumorganisms with OmpA antiserum reduces their abilities to infect HL-60 cells. The OmpA N-terminal region is predicted to contain the protein's extracellular domain. GlutathioneS-transferase (GST)-tagged versions of OmpA and OmpA amino acids 19 to 74 (OmpA19-74) but not OmpA75-205bind to, and competitively inhibitA. phagocytophiluminfection of, host cells. Pretreatment of host cells with sialidase or trypsin reduces or nearly eliminates, respectively, GST-OmpA adhesion. Therefore, OmpA interacts with sialylated glycoproteins. This study identifies the firstA. phagocytophilumadhesin-receptor pair and delineates the region of OmpA that is critical for infection.

scholarly journals The Helicobacter pylori Autotransporter ImaA (HP0289) Modulates the Immune Response and Contributes to Host Colonization

2012 ◽  
Vol 80 (7) ◽  
pp. 2286-2296 ◽  
Author(s):  
William E. Sause ◽  
Andrea R. Castillo ◽  
Karen M. Ottemann
Keyword(s):  
Immune Response ◽  
Helicobacter Pylori ◽  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Dependent Manner ◽  
Wild Type ◽  
Content Type ◽  
H Pylori ◽  
Murine Infections

ABSTRACTThe human pathogenHelicobacter pyloriemploys a diverse collection of outer membrane proteins to colonize, persist, and drive disease within the acidic gastric environment. In this study, we sought to elucidate the function of the host-induced geneHP0289, which encodes an uncharacterized outer membrane protein. We first generated an isogenicH. pylorimutant that lacksHP0289and found that the mutant has a colonization defect in single-strain infections and is greatly outcompeted in mouse coinfection experiments with wild-typeH. pylori. Furthermore, we used protease assays and biochemical fractionation coupled with an HP0289-targeted peptide antibody to verify that the HP0289 protein resides in the outer membrane. Our previous findings showed that theHP0289promoter is upregulated in the mouse stomach, and here we demonstrate thatHP0289expression is induced under acidic conditions in an ArsRS-dependent manner. Finally, we have shown that theHP0289mutant induces greater expression of the chemokine interleukin-8 (IL-8) and the cytokine tumor necrosis factor alpha (TNF-α) in gastric carcinoma cells (AGS). Similarly, transcription of the IL-8 homolog keratinocyte-derived chemokine (KC) is elevated in murine infections with the HP0289 mutant than in murine infections with wild-typeH. pylori. On the basis of this phenotype, we renamed HP0289 ImaA forimmunomodulatoryautotransporter protein. Our work has revealed that genes inducedin vivoplay an important role inH. pyloripathogenesis. Specifically, the outer membrane protein ImaA modulates a component of the host inflammatory response, and thus may allowH. pylorito fine tune the host immune response based on ImaA expression.

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