scholarly journals Glycosylation and biogenesis of a family of serine-rich bacterial adhesins

Microbiology ◽  
2009 ◽  
Vol 155 (2) ◽  
pp. 317-327 ◽  
Author(s):  
Meixian Zhou ◽  
Hui Wu
Keyword(s):  
Biosynthetic Pathway ◽  
Protein Glycosylation ◽  
Second Step ◽  
Complex Nature ◽  
Bacterial Physiology ◽  
Bacterial Proteins ◽  
New Family ◽  
Bacterial Adhesins ◽  
Platelet Binding ◽  
Associated Proteins

Glycosylation of bacterial proteins is an important process for bacterial physiology and pathophysiology. Both O- and N-linked glycan moieties have been identified in bacterial glycoproteins. The N-linked glycosylation pathways are well established in Gram-negative bacteria. However, the O-linked glycosylation pathways are not well defined due to the complex nature of known O-linked glycoproteins in bacteria. In this review, we examine a new family of serine-rich O-linked glycoproteins which are represented by fimbriae-associated adhesin Fap1 of Streptococcus parasanguinis and human platelet-binding protein GspB of Streptococcus gordonii. This family of glycoproteins is conserved in streptococcal and staphylococcal species. A gene cluster coding for glycosyltransferases and accessory Sec proteins has been implicated in the protein glycosylation. A two-step glycosylation model is proposed. Two glycosyltransferases interact with each other and catalyse the first step of the protein glycosylation in the cytoplasm; the cross-talk between glycosylation-associated proteins and accessory Sec components mediates the second step of the protein glycosylation, an emerging mechanism for bacterial O-linked protein glycosylation. Dissecting the molecular mechanism of this conserved biosynthetic pathway offers opportunities to develop new therapeutic strategies targeting this previously unrecognized pathway, as serine-rich glycoproteins have been shown to play a role in bacterial pathogenesis.

Dependence of heme biosynthesis on iron-sulfur cluster biogenesis: human ALAD is an unrecognized iron-sulfur protein

2020 ◽  
Author(s):  
Gang Liu ◽  
Debangsu Sil ◽  
Wing-Hang Tong ◽  
Nunziata Maio ◽  
J. Martin Bollinger ◽  
...  
Keyword(s):  
Metabolic Pathways ◽  
Biosynthetic Pathway ◽  
Aminolevulinic Acid ◽  
Heme Biosynthesis ◽  
Second Step ◽  
Iron Sulfur Cluster ◽  
Sulfur Cluster ◽  
Iron Sulfur ◽  
Sulfur Protein ◽  
Iron Sulfur Protein

Abstract Heme biosynthesis and iron-sulfur cluster (ISC) biogenesis are two major mammalian metabolic pathways that require iron. It has long been known that these two pathways interconnect, but the previously described interactions do not fully explain why heme biosynthesis depends on intact ISC biogenesis. Herein we have identified a previously unrecognized connection between these two pathways through our discovery that human aminolevulinic acid dehydratase (ALAD), which catalyzes the second step of heme biosynthesis, is an Fe-S protein. We found that several highly conserved cysteines and an Ala306-Phe307-Arg308 motif of human ALAD are important for [Fe4S4] cluster acquisition and coordination. The enzymatic activity of human ALAD was greatly reduced upon loss of its Fe-S cluster, which resulted in reduced heme biosynthesis in human cells. Our findings explain why heme biosynthesis depends on intact ISC biogenesis, as ALAD provides an early Fe-S-dependent checkpoint in the heme biosynthetic pathway.

scholarly journals Crosstalk among Indoleamines, Neuropeptides and JH/20E in Regulation of Reproduction in the American Cockroach, Periplaneta americana

Insects ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 155 ◽  
Author(s):  
A. S. M. Kamruzzaman ◽  
Azam Mikani ◽  
Amr A. Mohamed ◽  
Azza M. Elgendy ◽  
Makio Takeda
Keyword(s):  
Oocyte Maturation ◽  
Biosynthetic Pathway ◽  
Periplaneta Americana ◽  
American Cockroach ◽  
Second Step ◽  
Double Stranded Rna ◽  
Vitellogenin Receptor ◽  
Genes Encoding ◽  
Key Enzyme ◽  
Indoleamine Metabolism

Although the regulation of vitellogenesis in insects has been mainly discussed in terms of ‘classical’ lipid hormones, juvenile hormone (JH), and 20-hydroxyecdysone (20E), recent data support the notion that this process must be adjusted in harmony with a nutritional input/reservoir and involvement of certain indoleamines and neuropeptides in regulation of such process. This study focuses on crosstalks among these axes, lipid hormones, monoamines, and neuropeptides in regulation of vitellogenesis in the American cockroach Periplaneta americana with novel aspects in the roles of arylalkylamine N-acetyltransferase (aaNAT), a key enzyme in indoleamine metabolism, and the enteroendocrine peptides; crustacean cardioactive peptide (CCAP) and short neuropeptide F (sNPF). Double-stranded RNA against aaNAT (dsRNAaaNAT) was injected into designated-aged females and the effects were monitored including the expressions of aaNAT itself, vitellogenin 1 and 2 (Vg1 and Vg2) and the vitellogenin receptor (VgR) mRNAs, oocyte maturation and changes in the hemolymph peptide concentrations. Effects of peptides application and 20E were also investigated. Injection of dsRNAaaNAT strongly suppressed oocyte maturation, transcription of Vg1, Vg2, VgR, and genes encoding JH acid- and farnesoate O-methyltransferases (JHAMT and FAMeT, respectively) acting in the JH biosynthetic pathway. However, it did not affect hemolymph concentrations of CCAP and sNPF. Injection of CCAP stimulated, while sNPF suppressed oocyte maturation and Vgs/VgR transcription, i.e., acting as allatomedins. Injection of CCAP promoted, while sNPF repressed ecdysteroid (20E) synthesis, particularly at the second step of Vg uptake. 20E also affected the JH biosynthetic pathway and Vg/VgR synthesis. The results revealed that on the course of vitellogenesis, JH- and 20E-mediated regulation occurs downstream to indoleamines- and peptides-mediated regulations. Intricate mutual interactions of these regulatory routes must orchestrate reproduction in this species at the highest potency.

The structure of SAV1646 fromStaphylococcus aureusbelonging to a new `ribosome-associated' subfamily of bacterial proteins

2015 ◽  
Vol 71 (2) ◽  
pp. 332-337 ◽  
Author(s):  
Yuri N. Chirgadze ◽  
Teresa E. Clarke ◽  
Vladimir Romanov ◽  
Gera Kisselman ◽  
Jean Wu-Brown ◽  
...  
Keyword(s):  
Ribosomal Proteins ◽  
Rotation Axis ◽  
Genomic Structure ◽  
Large Subunit ◽  
Functional Model ◽  
Homology Search ◽  
Bacterial Proteins ◽  
Bacterial Ribosome ◽  
Acid Protein ◽  
Associated Proteins

The crystal structure of the SAV1646 protein from the pathogenic microorganismStaphylococcus aureushas been determined at 1.7 Å resolution. The 106-amino-acid protein forms a two-layer sandwich with α/β topology. The protein molecules associate as dimers in the crystal and in solution, with the monomers related by a pseudo-twofold rotation axis. A sequence-homology search identified the protein as a member of a new subfamily of yet uncharacterized bacterial `ribosome-associated' proteins with at least 13 members to date. A detailed analysis of the crystal protein structure along with the genomic structure of the operon containing thesav1646gene allowed a tentative functional model of this protein to be proposed. The SAV1646 dimer is assumed to form a complex with ribosomal proteins L21 and L27 which could help to complete the assembly of the large subunit of the ribosome.

scholarly journals Heteromeric Interactions among Nucleoid-Associated Bacterial Proteins: Localization of StpA-Stabilizing Regions in H-NS of Escherichia coli

2001 ◽  
Vol 183 (7) ◽  
pp. 2343-2347 ◽  
Author(s):  
Jörgen Johansson ◽  
Sven Eriksson ◽  
Berit Sondén ◽  
Sun Nyunt Wai ◽  
Bernt Eric Uhlin
Keyword(s):  
Escherichia Coli ◽  
Stable Form ◽  
Lon Protease ◽  
Wild Type ◽  
Bacterial Proteins ◽  
Regulatory Systems ◽  
Associated Proteins ◽  
Gene Regulatory

ABSTRACT The nucleoid-associated proteins H-NS and StpA inEscherichia coli bind DNA as oligomers and are implicated in gene regulatory systems. There is evidence for both homomeric and heteromeric H-NS–StpA complexes. The two proteins show differential turnover, and StpA was previously found to be subject to protease-mediated degradation by the Lon protease. We investigated which regions of the H-NS protein are able to prevent degradation of StpA. A set of truncated H-NS derivatives was tested for their ability to mediate StpA stability and to form heteromers in vitro. The data indicate that H-NS interacts with StpA at two regions and that the presence of at least one of the H-NS regions is necessary for StpA stability. Our results also suggest that a proteolytically stable form of StpA, StpAF21C, forms dimers, whereas wild-type StpA in the absence of H-NS predominantly forms tetramers or oligomers, which are more susceptible to proteolysis.

scholarly journals The HMGB chromatin protein Nhp6A can bypass obstacles when traveling on DNA

2020 ◽  
Vol 48 (19) ◽  
pp. 10820-10831
Author(s):  
Kiyoto Kamagata ◽  
Kana Ouchi ◽  
Cheng Tan ◽  
Eriko Mano ◽  
Sridhar Mandali ◽  
...  
Keyword(s):  
Dna Binding ◽  
Single Molecule ◽  
Binding Proteins ◽  
Dna Binding Proteins ◽  
Binding Modes ◽  
Dna Structures ◽  
Bacterial Proteins ◽  
Associated Proteins ◽  
Diffusion Mechanisms ◽  
Dynamics Simulations

Abstract DNA binding proteins rapidly locate their specific DNA targets through a combination of 3D and 1D diffusion mechanisms, with the 1D search involving bidirectional sliding along DNA. However, even in nucleosome-free regions, chromosomes are highly decorated with associated proteins that may block sliding. Here we investigate the ability of the abundant chromatin-associated HMGB protein Nhp6A from Saccharomyces cerevisiae to travel along DNA in the presence of other architectural DNA binding proteins using single-molecule fluorescence microscopy. We observed that 1D diffusion by Nhp6A molecules is retarded by increasing densities of the bacterial proteins Fis and HU and by Nhp6A, indicating these structurally diverse proteins impede Nhp6A mobility on DNA. However, the average travel distances were larger than the average distances between neighboring proteins, implying Nhp6A is able to bypass each of these obstacles. Together with molecular dynamics simulations, our analyses suggest two binding modes: mobile molecules that can bypass barriers as they seek out DNA targets, and near stationary molecules that are associated with neighboring proteins or preferred DNA structures. The ability of mobile Nhp6A molecules to bypass different obstacles on DNA suggests they do not block 1D searches by other DNA binding proteins.

Phytoene photoinduction in a carotenoid mutant of Neurospora crassa

1976 ◽  
Vol 54 (21) ◽  
pp. 2445-2448 ◽  
Author(s):  
J. C. Lansbergen ◽  
R. L. Renaud ◽  
R. E. Subden
Keyword(s):  
Neurospora Crassa ◽  
Mutant Strain ◽  
Biosynthetic Pathway ◽  
Dry Weight ◽  
Carotenoid Content ◽  
Second Step ◽  
Light Induction ◽  
Wild Type

The dynamics of carotenoid photoinduction in N. crassa have been studied by comparing a wild type and a mutant strain lacking the second step (phytoene dehydrogenation) in the carotene biosynthetic pathway. The data indicate that dark-grown cultures contain 113 to 150 μg carotenoid per gram dry weight and that light induction can double the carotenoid content. Phytoene synthesis and phytoene dehydrogenations are photoregulated independently.

scholarly journals Functional Characterization of Bacterial Oligosaccharyltransferases Involved in O-Linked Protein Glycosylation

2007 ◽  
Vol 189 (22) ◽  
pp. 8088-8098 ◽  
Author(s):  
Amirreza Faridmoayer ◽  
Messele A. Fentabil ◽  
Dominic C. Mills ◽  
John S. Klassen ◽  
Mario F. Feldman
Keyword(s):  
Sequence Similarity ◽  
Functional Characterization ◽  
Protein Glycosylation ◽  
Structural Components ◽  
En Bloc ◽  
E Coli ◽  
New Family ◽  
Type Iv ◽  
Domains Of Life

ABSTRACT Protein glycosylation is an important posttranslational modification that occurs in all domains of life. Pilins, the structural components of type IV pili, are O glycosylated in Neisseria meningitidis, Neisseria gonorrhoeae, and some strains of Pseudomonas aeruginosa. In this work, we characterized the P. aeruginosa 1244 and N. meningitidis MC58 O glycosylation systems in Escherichia coli. In both cases, sugars are transferred en bloc by an oligosaccharyltransferase (OTase) named PglL in N. meningitidis and PilO in P. aeruginosa. We show that, like PilO, PglL has relaxed glycan specificity. Both OTases are sufficient for glycosylation, but they require translocation of the undecaprenol-pyrophosphate-linked oligosaccharide substrates into the periplasm for activity. Whereas PilO activity is restricted to short oligosaccharides, PglL is able to transfer diverse oligo- and polysaccharides. This functional characterization supports the concept that despite their low sequence similarity, PilO and PglL belong to a new family of “O-OTases” that transfer oligosaccharides from lipid carriers to hydroxylated amino acids in proteins. To date, such activity has not been identified for eukaryotes. To our knowledge, this is the first report describing recombinant O glycoproteins synthesized in E. coli.

scholarly journals Neutron structures of theHelicobacter pylori5′-methylthioadenosine nucleosidase highlight proton sharing and protonation states

2016 ◽  
Vol 113 (48) ◽  
pp. 13756-13761 ◽  
Author(s):  
Michael T. Banco ◽  
Vidhi Mishra ◽  
Andreas Ostermann ◽  
Tobias E. Schrader ◽  
Gary B. Evans ◽  
...  
Keyword(s):  
Biosynthetic Pathway ◽  
Catalytic Mechanism ◽  
Enzymatic Reaction ◽  
Second Step ◽  
Binding Affinities ◽  
Wild Type ◽  
Protonation State ◽  
X Ray ◽  
Hydrolysis Of ◽  
Unconventional Hydrogen Bond

MTAN (5′-methylthioadenosine nucleosidase) catalyzes the hydrolysis of theN-ribosidic bond of a variety of adenosine-containing metabolites. TheHelicobacter pyloriMTAN (HpMTAN) hydrolyzes 6-amino-6-deoxyfutalosine in the second step of the alternative menaquinone biosynthetic pathway. Substrate binding of the adenine moiety is mediated almost exclusively by hydrogen bonds, and the proposed catalytic mechanism requires multiple proton-transfer events. Of particular interest is the protonation state of residue D198, which possesses a pKaabove 8 and functions as a general acid to initiate the enzymatic reaction. In this study we present three corefined neutron/X-ray crystal structures of wild-type HpMTAN cocrystallized withS-adenosylhomocysteine (SAH), Formycin A (FMA), and (3R,4S)-4-(4-Chlorophenylthiomethyl)-1-[(9-deaza-adenin-9-yl)methyl]-3-hydroxypyrrolidine (p-ClPh-Thio-DADMe-ImmA) as well as one neutron/X-ray crystal structure of an inactive variant (HpMTAN-D198N) cocrystallized with SAH. These results support a mechanism of D198 pKa elevation through the unexpected sharing of a proton with atom N7 of the adenine moiety possessing unconventional hydrogen-bond geometry. Additionally, the neutron structures also highlight active site features that promote the stabilization of the transition state and slight variations in these interactions that result in 100-fold difference in binding affinities between the DADMe-ImmA and ImmA analogs.

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