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https://www.readbyqxmd.com/read/28214390/robust-peptidoglycan-growth-by-dynamic-and-variable-multi-protein-complexes
#1
REVIEW
Manuel Pazos, Katharina Peters, Waldemar Vollmer
In Gram-negative bacteria such as Escherichia coli the peptidoglycan sacculus resides in the periplasm, a compartment that experiences changes in pH value, osmolality, ion strength and other parameters depending on the cell's environment. Hence, the cell needs robust peptidoglycan growth mechanisms to grow and divide under different conditions. Here we propose a model according to which the cell achieves robust peptidoglycan growth by employing dynamic multi-protein complexes, which assemble with variable composition from freely diffusing sets of peptidoglycan synthases, hydrolases and their regulators, whereby the composition of the active complexes depends on the cell cycle state - cell elongation or division - and the periplasmic growth conditions...
February 15, 2017: Current Opinion in Microbiology
https://www.readbyqxmd.com/read/28211111/regulation-of-nrf-operon-expression-in-pathogenic-enteric-bacteria-sequence-divergence-reveals-new-regulatory-complexity
#2
Rita E Godfrey, David J Lee, Stephen J W Busby, Douglas F Browning
The Escherichia coli K-12 nrf operon encodes a periplasmic nitrite reductase, the expression of which is driven from a single promoter, pnrf. Expression from pnrf is activated by the FNR transcription factor in response to anaerobiosis and further increased in response to nitrite by the response regulator proteins, NarL and NarP. FNR-dependent transcription is suppressed by the binding of two nucleoid associated proteins, IHF and Fis. As Fis levels increase in cells grown in rich medium, the positioning of its binding site, overlapping the promoter -10 element, ensures that pnrf is sharply repressed...
February 17, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28198457/identification-of-a-novel-type-iii-secretion-associated-outer-membrane-bound-protein-from-xanthomonas-campestris-pv-campestris
#3
Lei Li, Rui-Fang Li, Zhen-Hua Ming, Guang-Tao Lu, Ji-Liang Tang
Many bacterial pathogens employ the type III secretion system (T3SS) to translocate effector proteins into eukaryotic cells to overcome host defenses. To date, most of our knowledge about the T3SS molecular architecture comes from the studies on animal pathogens. In plant pathogens, nine Hrc proteins are believed to be structural components of the T3SS, of which HrcC and HrcJ form the outer and inner rings of the T3SS, respectively. Here, we demonstrated that a novel outer membrane-bound protein (HpaM) of Xanthomonas campestris pv...
February 15, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28194143/novel-immunity-proteins-associated-with-colicin-m-like-bacteriocins-exhibit-promiscuous-protection-in-pseudomonas
#4
Maarten G K Ghequire, Lieselore Kemland, René De Mot
Bacteriocins related to colicin M, acting via cleavage of the cell wall precursor lipid II, have been characterized in γ- and β-proteobacteria. Depending on the species, immunity is provided by either an inner membrane-anchored periplasmic protein or by an integral membrane protein. In Pseudomonas however, the immunity partner of colicin M-like bacteriocins remains unknown. Based on an in silico analysis in pseudomonad genomes, we here identify a gene encoding a putative immunity partner that represents a novel type of integral membrane protein (PmiA, Pseudomonas colicin M-like immunity type A)...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28193899/structure-of-a-lipid-a-phosphoethanolamine-transferase-suggests-how-conformational-changes-govern-substrate-binding
#5
Anandhi Anandan, Genevieve L Evans, Karmen Condic-Jurkic, Megan L O'Mara, Constance M John, Nancy J Phillips, Gary A Jarvis, Siobhan S Wills, Keith A Stubbs, Isabel Moraes, Charlene M Kahler, Alice Vrielink
Multidrug-resistant (MDR) gram-negative bacteria have increased the prevalence of fatal sepsis in modern times. Colistin is a cationic antimicrobial peptide (CAMP) antibiotic that permeabilizes the bacterial outer membrane (OM) and has been used to treat these infections. The OM outer leaflet is comprised of endotoxin containing lipid A, which can be modified to increase resistance to CAMPs and prevent clearance by the innate immune response. One type of lipid A modification involves the addition of phosphoethanolamine to the 1 and 4' headgroup positions by phosphoethanolamine transferases...
February 13, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28192658/iiron-release-from-the-siderophore-pyoverdine-in-pseudomonas-aeruginosa-involves-three-new-actors-fpvc-fpvg-and-fpvh
#6
Géraldine Ganne, Karl Brillet, Beata Basta, Beatrice Roche, Françoise Hoegy, Véronique Gasser, Isabelle J Schalk
Siderophores are iron chelators produced by bacteria to access iron, an essential nutriment. Pyoverdine (PVDI), the major siderophore produced by Pseudomonas aeruginosa PAO1, consists of a fluorescent chromophore linked to an octapeptide. The ferric-form of PVDI is transported from the extracellular environment into the periplasm by the outer membrane transporter, FpvA. Iron is then released from the siderophore in the periplasm by a mechanism that does not involve chemical modification of the chelator, but an iron reduction step...
February 13, 2017: ACS Chemical Biology
https://www.readbyqxmd.com/read/28191562/fbpa-iron-storage-and-release-are-governed-by-periplasmic-microenvironments
#7
Ozge Sensoy, Ali Rana Atilgan, Canan Atilgan
Ferric binding protein (FbpA) is part of an elaborate iron piracy mechanism evolved in Gram-negative bacteria, shuttling iron in the periplasmic space, from the outer to the cytoplasmic membrane side. We address how the dissociation process of iron is facilitated, since the binding constant of iron is on the order of 10(18) M(-1) at 6.5 pH and 200 mM ionic strength (IS). We monitor the conformational preferences of FbpA by extensive molecular dynamics (MD) simulations under conditions where IS, charge states of iron coordinating tyrosines and pH are varied, as well as when a mutation is introduced at an allosteric site...
February 13, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28188291/negative-stain-single-particle-em-of-the-maltose-transporter-in-nanodiscs-reveals-asymmetric-closure-of-malk2-and-catalytic-roles-of-atp-male-and-maltose
#8
Lucien Fabre, Huan Bao, James Innes, Franck Duong, Isabelle Rouiller
The Escherichia coli MalE-MalFGK2 complex is one of the best characterized members of the large and ubiquitous family of ATP-binding cassette (ABC) transporters. It is composed of a membrane-spanning heterodimer, MalF-MalG; a homodimeric ATPase, MalK2; and a periplasmic maltose receptor, MalE. Opening and closure of MalK2 is coupled to conformational changes in MalF-MalG and the alternate exposition of the substrate-binding site to either side of the membrane. To further define this alternate access mechanism and the impact of ATP, MalE and maltose on the conformation of the transporter during the transport cycle, we have reconstituted MalFGK2 in nanodiscs and analyzed its conformations under 10 different biochemical conditions using negative stain single particle EM...
February 10, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28186406/substrate-trapping-in-the-siderophore-tailoring-enzyme-pvdq
#9
Kenneth D Clevenger, Romila Mascarenhas, Daniel Catlin, Rui Wu, Neil L Kelleher, Eric J Drake, Andrew M Gulick, Dali Liu, Walter Fast
Siderophore biosynthesis by Pseudomonas aeruginosa enhances virulence and represents an attractive drug target. PvdQ functions in the type-1 pyoverdine biosynthetic pathway by removing a myristoyl anchor from a pyoverdine precursor, allowing eventual release from the periplasm. A circularly permuted version of PvdQ bypasses the self-processing step of this Ntn-hydrolase and retains the activity, selectivity, and structure of wild-type PvdQ, as revealed by a 1.8 Å resolution X-ray crystal structure. A 2.55 Å resolution structure of the inactive S1A/N269D-cpPvdQ mutant in complex with the pyoverdine precursor PVDIq reveals a specific binding pocket for the d-Tyr of this modified peptide substrate...
February 15, 2017: ACS Chemical Biology
https://www.readbyqxmd.com/read/28177793/biocontrol-of-i-burkholderia-cepacia-i-complex-bacteria-and-bacterial-phytopathogens-by-i-bdellovibrio-bacteriovorus-i
#10
Damian McNeely, Ryan M Chanyi, James S Dooley, John E Moore, Susan F Koval
<i>Bdellovibrio</i> and like organisms are predatory bacteria that have the unusual property of using the cytoplasmic constituents of other Gram-negative bacteria as nutrients. These predators may thus provide an alternative approach to the biocontrol of human and plant pathogens. Predators were isolated in enrichment cultures with soil and sewage on <i>Burkholderia cenocepacia</i> strains K56-2 and J2315 as prey cells. Three isolates (DM7C, DM8A and DM11A) were identified as <i>Bdellovibrio bacteriovorus</i> based on morphology, a periplasmic life cycle and 16S rRNA gene sequencing...
December 22, 2016: Canadian Journal of Microbiology
https://www.readbyqxmd.com/read/28168783/a-novel-signal-transduction-protein-combination-of-solute-binding-and-tandem-pas-like-sensor-domains-in-one-polypeptide-chain
#11
R Wu, R Wilton, M Cuff, M Endres, G Babnigg, J N Edirisinghe, C S Henry, A Joachimiak, M Schiffer, And P R Pokkuluri
We report the structural and biochemical characterization of a novel periplasmic ligand-binding protein, Dret_0059, from Desulfohalobium retbaense DSM 5692, an organism isolated from the Salt Lake Retba in Senegal. The structure of the protein consists of a unique combination of a periplasmic solute binding protein (SBP) domain at the N-terminal and a tandem PAS-like sensor domain at the C-terminal region. SBP domains are found ubiquitously and their best known function is in solute transport across membranes...
February 7, 2017: Protein Science: a Publication of the Protein Society
https://www.readbyqxmd.com/read/28168761/functional-clues-from-the-crystal-structure-of-an-orphan-periplasmic-ligand-binding-protein-from-treponema-pallidum
#12
Chad A Brautigam, Ranjit K Deka, Wei Z Liu, Diana R Tomchick, Michael V Norgard
The spirochete Treponema pallidum is the causative agent of syphilis, a sexually transmitted infection of major global importance. Other closely related subspecies of Treponema also are the etiological agents of the endemic treponematoses, such as yaws, pinta, and bejel. The inability of T. pallidum and its close relatives to be cultured in vitro has prompted efforts to characterize T. pallidum's proteins structurally and biophysically, particularly those potentially relevant to treponemal membrane biology, with the goal of possibly revealing the functions of those proteins...
February 7, 2017: Protein Science: a Publication of the Protein Society
https://www.readbyqxmd.com/read/28167520/a-new-essential-cell-division-protein-in-caulobacter-crescentus
#13
Aurora Osorio, Laura Camarena, Miguel Angel Cevallos, Sebastian Poggio
: Bacterial cell division is a complex process that relies on a multiprotein complex composed of a core of widely conserved and generally essential proteins and on accessory proteins that vary in number and identity in different bacteria. The assembly of this complex and in particular, the initiation of constriction is a regulated process that has come under intensive study. In this work, we characterize the function of DipI, a protein conserved in alpha and beta proteobacteria that is essential in Caulobacter crescentus Our results show that DipI is a periplasmic protein that is recruited late to the division site and that is required for the initiation of constriction...
February 6, 2017: Journal of Bacteriology
https://www.readbyqxmd.com/read/28167162/disparate-response-to-microoxia-and-nitrogen-oxides-of-the-bradyrhizobium-japonicum-napedabc-nirk-and-norcbqd-denitrification-genes
#14
Emilio Bueno, Eloy F Robles, María J Torres, Tino Krell, Eulogio J Bedmar, María J Delgado, Socorro Mesa
Expression of the Bradyrhizobium japonicum napEDABC, nirK and norCBQD denitrification genes requires low oxygen (O2) tension and nitrate (NO3(-)), through a regulatory network comprised of two coordinated cascades, FixLJ-FixK2-NnrR and RegSR-NifA. To precisely understand how these signals are integrated in the FixLJ-FixK2-NnrR circuit, we analyzed β-Galactosidase activities from napE-lacZ, nirK-lacZ and norC-lacZ fusions and performed analyses of NapC and NorC levels as well as periplasmic nitrate reductase (Nap) activity, in B...
February 3, 2017: Nitric Oxide: Biology and Chemistry
https://www.readbyqxmd.com/read/28159891/an-amidase-is-required-for-proper-intercellular-communication-in-the-filamentous-cyanobacterium-anabaena-sp-pcc-7120
#15
Zhenggao Zheng, Amin Omairi-Nasser, Xiying Li, Chunxia Dong, Yan Lin, Robert Haselkorn, Jindong Zhao
Channels that cross cell walls and connect the cytoplasm of neighboring cells in multicellular cyanobacteria are pivotal for intercellular communication. We find that the product of the gene all1140 of the filamentous cyanobacterium Anabaena sp. PCC 7120 is required for proper channel formation. All1140 encodes an amidase that hydrolyses purified peptidoglycans. An All1140-GFP fusion protein is located at the Z-ring in the periplasmic space during most of the cell cycle. An all1140-null mutant (M40) was unable to grow diazotrophically, and no mature heterocysts were observed in the absence of combined nitrogen...
February 3, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28159581/recombinant-expression-of-intrepicalcin-from-the-scorpion-vaejovis-intrepidus-and-its-effect-on-skeletal-ryanodine-receptors
#16
Leonel Vargas-Jaimes, Liang Xiao, Jing Zhang, Lourival D Possani, Héctor H Valdivia, Verónica Quintero-Hernández
BACKGROUND: Scorpion venoms contain toxins that modulate ionic channels, among which are the calcins, a small group of short, basic peptides with an Inhibitor Cystine Knot (ICK) motif that target calcium release channels/ryanodine receptors (RyRs) with high affinity and selectivity. Here we describe the heterologous expression of Intrepicalcin, identified by transcriptomic analysis of venomous glands from Vaejovis intrepidus. METHODS: Recombinant Intrepicalcin was obtained in Escherichia coli BL21-DE3 (periplasm) by fusing the Intrepicalcin gene to sequences coding for signal-peptide, thioredoxin, His-tag and enterokinase cleavage site...
January 31, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28157627/modeling-and-simulation-of-bacterial-outer-membranes-and-interactions-with-membrane-proteins
#17
REVIEW
Dhilon S Patel, Yifei Qi, Wonpil Im
The outer membrane (OM) of Gram-negative bacteria is composed of phospholipids in the periplasmic leaflet and lipopolysaccharides (LPS) in the external leaflet, along with β-barrel OM proteins (OMPs) and lipidated periplasmic lipoproteins. As a defensive barrier to toxic compounds, an LPS molecule has high antigenic diversity and unique combination of OM-anchored lipid A with core oligosaccharides and O-antigen polysaccharides, creating dynamic protein-LPS and LPS-LPS interactions. Here, we review recent efforts on modeling and simulation of native-like bacterial OMs to explore structures, dynamics, and interactions of different OM components and their roles in transportation of ions, substrates, and antibiotics across the OM and accessibility of monoclonal antibodies (mAbs) to surface epitopes...
January 31, 2017: Current Opinion in Structural Biology
https://www.readbyqxmd.com/read/28144238/cj1199-affect-the-development-of-erythromycin-resistance-in-campylobacter-jejuni-through-regulation-of-leucine-biosynthesis
#18
Haihong Hao, Fei Li, Jing Han, Steven L Foley, Menghong Dai, Xu Wang, Yulian Wang, Lingli Huang, Yawei Sun, Zhenli Liu, Zonghui Yuan
The aim of this study was to reveal the biological function of Cj1199 which was overexpressed in the laboratory induced erythromycin resistant strains. The Cj1199 deletion mutant (ΦCj1199) was constructed via insertional inactivation from its parent strain Campylobacter jejuni NCTC11168. The ΦCj1199 and NCTC11168 were then subjected to microarray and real-time PCR to find gene pathway of Cj1199. The antimicrobial susceptibility, antimicrobial resistance development, growth characteristics and leucine metabolism were examined to confirm the biological function of Cj1199...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28138098/genetic-and-mechanistic-analyses-of-the-periplasmic-domain-of-the-enterohemorrhagic-e-coli-ehec-qsec-histidine-sensor-kinase
#19
Christopher T Parker, Regan Russell, Jacqueline W Njoroge, Angel G Jimenez, Ron Taussig, Vanessa Sperandio
: The histidine sensor kinase (HK) QseC, senses autoinducer-3 (AI-3), and the adrenergic hormones epinephrine and norepinephrine. Upon sensing these signals, QseC acts through three response regulators (RRs) to regulate expression of virulence genes in enterohemorrhagic E. coli (EHEC). The QseB, QseF and KdpE RRs that are phosphorylated by QseC constitute a tripartite signaling cascade having different and overlapping targets, including flagella and motility, the type three secretion system encoded by the locus of enterocyte effacement (LEE), and Shiga toxin...
January 30, 2017: Journal of Bacteriology
https://www.readbyqxmd.com/read/28131879/heterologous-expression-of-halomonas-halodenitrificans-nitric-oxide-reductase-and-its-n-terminally-truncated-norc-subunit-in-escherichia-coli
#20
Nobuhiko Sakurai, Kunishige Kataoka, Noriko Sugaya, Takaki Shimodaira, Mie Iwamoto, Munehiro Shoda, Hajime Horiuchi, Miyuki Kiyono, Yasuke Ohta, Bambang Triwiyono, Daisuke Seo, Takeshi Sakurai
Halomonas halodenitrificans nitric oxide reductase (NOR) is the membrane-bound heterodimer complex of NorC, which contains a low-spin heme c center, and NorB, which contains a low-spin heme b center, a high-spin heme b3 center, and a non-heme FeB center. The soluble domain of NorC, NorC* (ΔMet1-Val37) was heterologously expressed in Escherichia coli using expression plasmids harboring the truncated norC gene deleted of its 84 5'-terminal nucleotides. Analogous scission of the N-terminal helix as the membrane anchor took place when the whole norC gene was used...
January 21, 2017: Journal of Inorganic Biochemistry
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