scholarly journals Identification and Characterization of Porphyromonas gingivalis Client Proteins That Bind to Streptococcus oralis Glyceraldehyde-3-Phosphate Dehydrogenase

2012 ◽  
Vol 81 (3) ◽  
pp. 753-763 ◽  
Author(s):  
Kazuhiko Maeda ◽  
Hideki Nagata ◽  
Masae Kuboniwa ◽  
Miki Ojima ◽  
Tsukasa Osaki ◽  
...  
Keyword(s):  
Amino Acid ◽  
Porphyromonas Gingivalis ◽  
Interaction Analysis ◽  
Site Directed Mutagenesis ◽  
Receptor Protein ◽  
Oral Streptococci ◽  
Amino Acid Residues ◽  
Content Type ◽  
Streptococcus Oralis ◽  
Client Proteins

ABSTRACTCoaggregation ofPorphyromonas gingivalisand oral streptococci is thought to play an important role inP. gingivaliscolonization. Previously, we reported thatP. gingivalismajor fimbriae interacted withStreptococcus oralisglyceraldehyde-3-phosphate dehydrogenase (GAPDH), and that amino acid residues 166 to 183 of GAPDH exhibited strong binding activity towardP. gingivalisfimbriae (H. Nagata, M. Iwasaki, K. Maeda, M. Kuboniwa, E. Hashino, M. Toe, N. Minamino, H. Kuwahara, and S. Shizukuishi, Infect. Immun.77:5130–5138, 2009). The present study aimed to identify and characterizeP. gingivaliscomponents other than fimbriae that interact withS. oralisGAPDH. A pulldown assay was performed to detect potential interactions betweenP. gingivalisclient proteins andS. oralisrecombinant GAPDH with amino acid residues 166 to 183 deleted by site-directed mutagenesis. Seven proteins, namely,tonB-dependent receptor protein (RagA4), arginine-specific proteinase B, 4-hydroxybutyryl-coenzyme A dehydratase (AbfD), lysine-specific proteinase, GAPDH, NAD-dependent glutamate dehydrogenase (GDH), and malate dehydrogenase (MDH), were identified by two-dimensional gel electrophoresis followed by proteomic analysis using tandem mass spectrometry. Interactions between these client proteins andS. oralisGAPDH were analyzed with a biomolecular interaction analysis system.S. oralisGAPDH showed high affinity for five of the seven client proteins (RagA4, AbfD, GAPDH, GDH, and MDH). Interactions betweenP. gingivalisandS. oraliswere measured by a turbidimetric method and fluorescence microscopy. RagA4, AbfD, and GDH enhanced coaggregation, whereas GAPDH and MDH inhibited coaggregation. Furthermore, the expression ofluxSinP. gingivaliswas upregulated by RagA4, AbfD, and GDH but was downregulated by MDH. These results indicate that the fiveP. gingivalisclient proteins function as regulators inP. gingivalisbiofilm formation with oral streptococci.

scholarly journals Identification of the Binding Domain of Streptococcus oralis Glyceraldehyde-3-Phosphate Dehydrogenase for Porphyromonas gingivalis Major Fimbriae

2009 ◽  
Vol 77 (11) ◽  
pp. 5130-5138 ◽  
Author(s):  
Hideki Nagata ◽  
Mio Iwasaki ◽  
Kazuhiko Maeda ◽  
Masae Kuboniwa ◽  
Ei Hashino ◽  
...  
Keyword(s):  
Amino Acid ◽  
Porphyromonas Gingivalis ◽  
Biofilm Formation ◽  
Binding Activity ◽  
Binding Domain ◽  
Laser Scanning Microscopy ◽  
Dependent Manner ◽  
Oral Streptococci ◽  
Amino Acid Residues ◽  
Streptococcus Oralis

ABSTRACT Porphyromonas gingivalis forms communities with antecedent oral biofilm constituent streptococci. P. gingivalis major fimbriae bind to glyceraldehyde-3-phosphate dehydrogenase (GAPDH) present on the streptococcal surface, and this interaction plays an important role in P. gingivalis colonization. This study identified the binding domain of Streptococcus oralis GAPDH for P. gingivalis fimbriae. S. oralis recombinant GAPDH (rGAPDH) was digested with lysyl endopeptidase. Cleaved fragments of rGAPDH were applied to a reverse-phase high-pressure liquid chromatograph equipped with a C18 column. Each peak was collected; the binding activity toward P. gingivalis recombinant fimbrillin (rFimA) was analyzed with a biomolecular interaction analysis system. The fragment displaying the strongest binding activity was further digested with various proteinases, after which the binding activity of each fragment was measured. The amino acid sequence of each fragment was determined by direct sequencing, mass spectrometric analysis, and amino acid analysis. Amino acid residues 166 to 183 of S. oralis GAPDH exhibited the strongest binding activity toward rFimA; confocal laser scanning microscopy revealed that the synthetic peptide corresponding to amino acid residues 166 to 183 of S. oralis GAPDH (pep166-183, DNFGVVEGLMTTIHAYTG) inhibits S. oralis-P. gingivalis biofilm formation in a dose-dependent manner. Moreover, pep166-183 inhibited interbacterial biofilm formation by several oral streptococci and P. gingivalis strains with different types of FimA. These results indicate that the binding domain of S. oralis GAPDH for P. gingivalis fimbriae exists within the region encompassing amino acid residues 166 to 183 of GAPDH and that pep166-183 may be a potent inhibitor of P. gingivalis colonization in the oral cavity.

scholarly journals Site-Directed Mutagenesis of HgcA and HgcB Reveals Amino Acid Residues Important for Mercury Methylation

2015 ◽  
Vol 81 (9) ◽  
pp. 3205-3217 ◽  
Author(s):  
Steven D. Smith ◽  
Romain Bridou ◽  
Alexander Johs ◽  
Jerry M. Parks ◽  
Dwayne A. Elias ◽  
...  
Keyword(s):  
Amino Acid ◽  
Inorganic Mercury ◽  
Desulfovibrio Desulfuricans ◽  
Site Directed Mutagenesis ◽  
Mercury Methylation ◽  
Amino Acid Residues ◽  
Content Type ◽  
Anaerobic Microorganisms ◽  
C Terminus ◽  
Methylation Capacity

ABSTRACTMethylmercury is a potent neurotoxin that is produced by anaerobic microorganisms from inorganic mercury by a recently discovered pathway. A two-gene cluster, consisting ofhgcAandhgcB, encodes two of the proteins essential for this activity.hgcAencodes a corrinoid protein with a strictly conserved cysteine proposed to be the ligand for cobalt in the corrinoid cofactor, whereashgcBencodes a ferredoxin-like protein thought to be an electron donor to HgcA. Deletion of either gene eliminates mercury methylation by the methylatorDesulfovibrio desulfuricansND132. Here, site-directed mutants of HgcA and HgcB were constructed to determine amino acid residues essential for mercury methylation. Mutations of the strictly conserved residue Cys93 in HgcA, the proposed ligand for the corrinoid cobalt, to Ala or Thr completely abolished the methylation capacity, but a His substitution produced measurable methylmercury. Mutations of conserved amino acids near Cys93 had various impacts on the methylation capacity but showed that the structure of the putative “cap helix” region harboring Cys93 is crucial for methylation function. In the ferredoxin-like protein HgcB, only one of two conserved cysteines found at the C terminus was necessary for methylation, but either cysteine sufficed. An additional, strictly conserved cysteine, Cys73, was also determined to be essential for methylation. This study supports the previously predicted importance of Cys93 in HgcA for methylation of mercury and reveals additional residues in HgcA and HgcB that facilitate the production of this neurotoxin.

scholarly journals Identification of Amino Acid Residues Involved in Heme Binding and Hemoprotein Utilization in the Porphyromonas gingivalis Heme Receptor HmuR

2006 ◽  
Vol 74 (2) ◽  
pp. 1222-1232 ◽  
Author(s):  
Xinyan Liu ◽  
Teresa Olczak ◽  
Hwai-Chen Guo ◽  
Dabney W. Dixon ◽  
Caroline Attardo Genco
Keyword(s):  
Amino Acid ◽  
Human Serum ◽  
Porphyromonas Gingivalis ◽  
Three Dimensional ◽  
Point Mutations ◽  
Homology Model ◽  
Site Directed Mutagenesis ◽  
Source Analysis ◽  
Heme Binding ◽  
Amino Acid Residues

ABSTRACT We have previously identified and characterized a heme/hemoglobin receptor, HmuR, in Porphyromonas gingivalis. To analyze the conserved amino acid residues of HmuR that may be involved in hemin/hemoprotein binding and utilization, we constructed a series of P. gingivalis A7436 hmuR mutants with amino acid replacements and characterized the ability of these mutants to utilize hemin and hemoproteins. Site-directed mutagenesis was employed to introduce mutations H95A, H434A, H95A-H434A, YRAP420-423YAAA, and NPDL442-445NAAA into HmuR in both P. gingivalis and Escherichia coli. Point mutations at H95 and H434 and in the NPDL motif of HmuR resulted in decreased binding to hemin, hemoglobin, and human serum albumin-hemin complex. Notably, mutations of these conserved sites and motifs led to reduced growth of P. gingivalis when human serum was used as the heme source. Analysis using a three-dimensional homology model of HmuR indicated that H95, H434, and the NPDL motif are present on apical or extracellular loops of HmuR, while the YRAP motif is present on the barrel wall. Taken together, these results support a role for H95, H434, and the NPDL motif of the P. gingivalis HmuR protein in heme binding and utilization of serum hemoproteins and the HmuR YRAP motif in serum hemoprotein utilization.

Chitosanase from Streptomyces sp. strain N174: a comparative review of its structure and function

1997 ◽  
Vol 75 (6) ◽  
pp. 687-696 ◽  
Author(s):  
Tamo Fukamizo ◽  
Ryszard Brzezinski
Keyword(s):  
Amino Acid ◽  
Amino Acid Sequence ◽  
Substrate Binding ◽  
Structure And Function ◽  
Site Directed Mutagenesis ◽  
Directed Mutagenesis ◽  
Amino Acid Residues ◽  
Streptomyces Sp ◽  
Binding Cleft ◽  
And Function

Novel information on the structure and function of chitosanase, which hydrolyzes the beta -1,4-glycosidic linkage of chitosan, has accumulated in recent years. The cloning of the chitosanase gene from Streptomyces sp. strain N174 and the establishment of an efficient expression system using Streptomyces lividans TK24 have contributed to these advances. Amino acid sequence comparisons of the chitosanases that have been sequenced to date revealed a significant homology in the N-terminal module. From energy minimization based on the X-ray crystal structure of Streptomyces sp. strain N174 chitosanase, the substrate binding cleft of this enzyme was estimated to be composed of six monosaccharide binding subsites. The hydrolytic reaction takes place at the center of the binding cleft with an inverting mechanism. Site-directed mutagenesis of the carboxylic amino acid residues that are conserved revealed that Glu-22 and Asp-40 are the catalytic residues. The tryptophan residues in the chitosanase do not participate directly in the substrate binding but stabilize the protein structure by interacting with hydrophobic and carboxylic side chains of the other amino acid residues. Structural and functional similarities were found between chitosanase, barley chitinase, bacteriophage T4 lysozyme, and goose egg white lysozyme, even though these proteins share no sequence similarities. This information can be helpful for the design of new chitinolytic enzymes that can be applied to carbohydrate engineering, biological control of phytopathogens, and other fields including chitinous polysaccharide degradation. Key words: chitosanase, amino acid sequence, overexpression system, reaction mechanism, site-directed mutagenesis.

scholarly journals Identification and characterization of amphibian SLC26A5 using RNA-Seq

BMC Genomics ◽  
2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Zhongying Wang ◽  
Qixuan Wang ◽  
Hao Wu ◽  
Zhiwu Huang
Keyword(s):  
Amino Acid ◽  
Inner Ear ◽  
Hair Cells ◽  
Rana Catesbeiana ◽  
Site Directed Mutagenesis ◽  
Amino Acid Residues ◽  
Rna Seq ◽  
American Bullfrog ◽  
Frog Species

Abstract Background Prestin (SLC26A5) is responsible for acute sensitivity and frequency selectivity in the vertebrate auditory system. Limited knowledge of prestin is from experiments using site-directed mutagenesis or domain-swapping techniques after the amino acid residues were identified by comparing the sequence of prestin to those of its paralogs and orthologs. Frog prestin is the only representative in amphibian lineage and the studies of it were quite rare with only one species identified. Results Here we report a new coding sequence of SLC26A5 for a frog species, Rana catesbeiana (the American bullfrog). In our study, the SLC26A5 gene of Rana has been mapped, sequenced and cloned successively using RNA-Seq. We measured the nonlinear capacitance (NLC) of prestin both in the hair cells of Rana’s inner ear and HEK293T cells transfected with this new coding gene. HEK293T cells expressing Rana prestin showed electrophysiological features similar to that of hair cells from its inner ear. Comparative studies of zebrafish, chick, Rana and an ancient frog species showed that chick and zebrafish prestin lacked NLC. Ancient frog’s prestin was functionally different from Rana. Conclusions We mapped and sequenced the SLC26A5 of the Rana catesbeiana from its inner ear cDNA using RNA-Seq. The Rana SLC26A5 cDNA was 2292 bp long, encoding a polypeptide of 763 amino acid residues, with 40% identity to mammals. This new coding gene could encode a functionally active protein conferring NLC to both frog HCs and the mammalian cell line. While comparing to its orthologs, the amphibian prestin has been evolutionarily changing its function and becomes more advanced than avian and teleost prestin.

Identification of Amino Acid Residues Underlying the Antiport Mechanism of the Mitochondrial Carnitine/Acylcarnitine Carrier by Site-Directed Mutagenesis and Chemical Labeling

Biochemistry ◽  
2014 ◽  
Vol 53 (44) ◽  
pp. 6924-6933 ◽  
Author(s):  
Nicola Giangregorio ◽  
Lara Console ◽  
Annamaria Tonazzi ◽  
Ferdinando Palmieri ◽  
Cesare Indiveri
Keyword(s):  
Amino Acid ◽  
Site Directed Mutagenesis ◽  
Directed Mutagenesis ◽  
Amino Acid Residues ◽  
Chemical Labeling

scholarly journals Identification of Key Amino Acid Residues Determining Product Specificity of 2,3-Oxidosqualene Cyclase in Siraitia grosvenorii

Catalysts ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 577 ◽  
Author(s):  
Jing Qiao ◽  
Jiushi Liu ◽  
Jingjing Liao ◽  
Zuliang Luo ◽  
Xiaojun Ma ◽  
...  
Keyword(s):  
Amino Acid ◽  
Site Directed Mutagenesis ◽  
Bioactive Molecules ◽  
Amino Acid Residues ◽  
Product Specificity ◽  
Oxidosqualene Cyclase ◽  
Siraitia Grosvenorii ◽  
Initial Substrate ◽  
New Strategy ◽  
Key Residues

Sterols and triterpenes are structurally diverse bioactive molecules generated through cyclization of linear 2,3-oxidosqualene. Based on carbocationic intermediates generated during the initial substrate preorganization step, oxidosqualene cyclases (OSCs) are roughly segregated into a dammarenyl cation group that predominantly catalyzes triterpenoid precursor products and a protosteryl cation group which mostly generates sterol precursor products. The mechanism of conversion between two scaffolds is not well understood. Previously, we have characterized a promiscuous OSC from Siraitia grosvenorii (SgCS) that synthesizes a novel cucurbitane-type triterpene cucurbitadienol as its main product. By integration of homology modeling, molecular docking and site-directed mutagenesis, we discover that five key amino acid residues (Asp486, Cys487, Cys565, Tyr535, and His260) may be responsible for interconversions between chair–boat–chair and chair–chair–chair conformations. The discovery of euphol, dihydrolanosterol, dihydroxyeuphol and tirucallenol unlocks a new path to triterpene diversity in nature. Our findings also reveal mechanistic insights into the cyclization of oxidosqualene into cucurbitane-type and lanostane-type skeletons, and provide a new strategy to identify key residues determining OSC specificity.

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