Structural Changes and Binding Characteristics of the Tetracycline-Repressor Binding Site on Induction

2006 ◽  
Vol 49 (12) ◽  
pp. 3444-3447 ◽  
Author(s):  
Harald Lanig ◽  
Olaf G. Othersen ◽  
Ute Seidel ◽  
Frank R. Beierlein ◽  
Thomas E. Exner ◽  
...  
Keyword(s):  
Binding Site ◽  
Structural Changes ◽  
Binding Characteristics ◽  
Repressor Binding Site ◽  
Tetracycline Repressor

scholarly journals Protein Sensing Device with Multi-Recognition Ability Composed of Self-Organized Glycopeptide Bundle

2020 ◽  
Vol 22 (1) ◽  
pp. 366
Author(s):  
Mao Arai ◽  
Tomohiro Miura ◽  
Yuriko Ito ◽  
Takatoshi Kinoshita ◽  
Masahiro Higuchi
Keyword(s):  
Binding Site ◽  
Lipid Bilayer ◽  
Structural Changes ◽  
Bilayer Membrane ◽  
Lipid Bilayer Membrane ◽  
Target Protein ◽  
Self Organization ◽  
Specific Response ◽  
Target Proteins ◽  
Recognition Ability

We designed and synthesized amphiphilic glycopeptides with glucose or galactose at the C-terminals. We observed the protein-induced structural changes of the amphiphilic glycopeptide assembly in the lipid bilayer membrane using transmission electron microscopy (TEM) and Fourier transform infrared reflection-absorption spectra (FTIR-RAS) measurements. The glycopeptides re-arranged to form a bundle that acted as an ion channel due to the interaction among the target protein and the terminal sugar groups of the glycopeptides. The bundle in the lipid bilayer membrane was fixed on a gold-deposited quartz crystal microbalance (QCM) electrode by the membrane fusion method. The protein-induced re-arrangement of the terminal sugar groups formed a binding site that acted as a receptor, and the re-binding of the target protein to the binding site induced the closing of the channel. We monitored the detection of target proteins by the changes of the electrochemical properties of the membrane. The response current of the membrane induced by the target protein recognition was expressed by an equivalent circuit consisting of resistors and capacitors when a triangular voltage was applied. We used peanut lectin (PNA) and concanavalin A (ConA) as target proteins. The sensing membrane induced by PNA shows the specific response to PNA, and the ConA-induced membrane responded selectively to ConA. Furthermore, PNA-induced sensing membranes showed relatively low recognition ability for lectin from Ricinus Agglutinin (RCA120) and mushroom lectin (ABA), which have galactose binding sites. The protein-induced self-organization formed the spatial arrangement of the sugar chains specific to the binding site of the target protein. These findings demonstrate the possibility of fabricating a sensing device with multi-recognition ability that can recognize proteins even if the structure is unknown, by the protein-induced self-organization process.

scholarly journals Chemical modification studies on a lectin from Saccharomyces cerevisiae (baker's yeast)

1987 ◽  
Vol 244 (3) ◽  
pp. 579-584 ◽  
Author(s):  
M Kundu ◽  
J Basu ◽  
A Ghosh ◽  
P Chakrabarti
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Chemical Modification ◽  
Binding Site ◽  
Structural Changes ◽  
Thiol Groups ◽  
Lectin Activity ◽  
Partial Protection ◽  
Sugar Binding ◽  
Arginine Residues ◽  
Glycine Ethyl Ester

The effect of chemical modification on a galactose-specific lectin isolated from a fatty acid auxotroph of Saccharomyces cerevisiae was investigated in order to identify the type of amino acids involved in its agglutinating activity. Modification of 50 free amino groups with succinic anhydride or citraconic anhydride led to an almost complete loss of activity. This could not be protected by the inhibitory sugar methyl alpha-D-galactopyranoside. Treatment with N-bromosuccinimide and N-acetylimidazole, for the modification of tryptophan and tyrosine residues, did not affect lectin activity. Modification of carboxy groups with glycine ethyl ester greatly affected lectin activity, although sugars afford partial protection. Modification of four thiol groups with N-ethylmaleimide was accompanied by a loss of 85% of the agglutinating activity, and two thiol groups were found to be present at the sugar-binding site of the lectin. Modification of 18 arginine residues with cyclohexane-1,2-dione and 26 histidine residues with ethoxyformic anhydride led to a loss of lectin activity. However, in these cases, modification was not protected by the abovementioned inhibitory sugar, suggesting the absence of these groups at the sugar-binding site. In all the cases, immunodiffusion studies with modified lectin showed no gross structural changes which could disrupt antigenic sites of the lectin.

scholarly journals Feedback Regulation of Lac Repressor Expression in Escherichia coli

2009 ◽  
Vol 191 (16) ◽  
pp. 5301-5303 ◽  
Author(s):  
Stefan Oehler
Keyword(s):  
Escherichia Coli ◽  
Binding Site ◽  
Negative Feedback ◽  
Feedback Regulation ◽  
Lac Repressor ◽  
Negative Feedback Regulation ◽  
Expression In Escherichia Coli ◽  
Weak Expression ◽  
Repressor Binding Site

ABSTRACT Negative feedback regulation, mediated through repressor binding site O3, which overlaps the lacI gene, could explain the robustness of the weak expression of Lac repressor. Significant autorepression of Lac repressor has never been ruled out. In the work presented here, the degree of autoregulation of Lac repressor was determined. It is negligible.

scholarly journals Analysis of a nucleotide-binding site of 5-lipoxygenase by affinity labelling: binding characteristics and amino acid sequences

2000 ◽  
Vol 351 (3) ◽  
pp. 697 ◽  
Author(s):  
Ying-Yi ZHANG ◽  
Tove HAMMARBERG ◽  
Olof RADMARK ◽  
Bengt SAMUELSSON ◽  
Carol F. NG ◽  
...  
Keyword(s):  
Amino Acid ◽  
Binding Site ◽  
Nucleotide Binding ◽  
Amino Acid Sequences ◽  
Nucleotide Binding Site ◽  
Binding Characteristics ◽  
Affinity Labelling

scholarly journals Analysis of a nucleotide-binding site of 5-lipoxygenase by affinity labelling: binding characteristics and amino acid sequences

2000 ◽  
Vol 351 (3) ◽  
pp. 697-707 ◽  
Author(s):  
Ying-Yi ZHANG ◽  
Tove HAMMARBERG ◽  
Olof RADMARK ◽  
Bengt SAMUELSSON ◽  
Carol F. NG ◽  
...  
Keyword(s):  
Amino Acid ◽  
Binding Site ◽  
Tertiary Structure ◽  
Nucleotide Binding ◽  
Peptide Sequencing ◽  
Amino Acid Sequences ◽  
Nucleotide Binding Site ◽  
Atp Binding ◽  
Binding Characteristics ◽  
Atp Binding Site

5-Lipoxygenase (5LO) catalyses the first two steps in the biosynthesis of leukotrienes, which are inflammatory mediators derived from arachidonic acid. 5LO activity is stimulated by ATP; however, a consensus ATP-binding site or nucleotide-binding site has not been found in its protein sequence. In the present study, affinity and photoaffinity labelling of 5LO with 5′-p-fluorosulphonylbenzoyladenosine (FSBA) and 2-azido-ATP showed that 5LO bound to the ATP analogues quantitatively and specifically and that the incorporation of either analogue inhibited ATP stimulation of 5LO activity. The stoichiometry of the labelling was 1.4mol of FSBA/mol of 5LO (of which ATP competed with 1mol/mol) or 0.94mol of 2-azido-ATP/mol of 5LO (of which ATP competed with 0.77mol/mol). Labelling with FSBA prevented further labelling with 2-azido-ATP, indicating that the same binding site was occupied by both analogues. Other nucleotides (ADP, AMP, GTP, CTP and UTP) also competed with 2-azido-ATP labelling, suggesting that the site was a general nucleotide-binding site rather than a strict ATP-binding site. Ca2+, which also stimulates 5LO activity, had no effect on the labelling of the nucleotide-binding site. Digestion with trypsin and peptide sequencing showed that two fragments of 5LO were labelled by 2-azido-ATP. These fragments correspond to residues 73–83 (KYWLNDDWYLK, in single-letter amino acid code) and 193–209 (FMHMFQSSWNDFADFEK) in the 5LO sequence. Trp-75 and Trp-201 in these peptides were modified by the labelling, suggesting that they were immediately adjacent to the C-2 position of the adenine ring of ATP. Given the stoichiometry of the labelling, the two peptide sequences of 5LO were probably near each other in the enzyme's tertiary structure, composing or surrounding the ATP-binding site of 5LO.

scholarly journals Calcium regulates tertiary structure and enzymatic activity of human endometase/matrilysin-2 and its role in promoting human breast cancer cell invasion

2007 ◽  
Vol 403 (1) ◽  
pp. 31-42 ◽  
Author(s):  
Seakwoo Lee ◽  
Hyun I. Park ◽  
Qing-Xiang Amy Sang
Keyword(s):  
Breast Cancer ◽  
Enzymatic Activity ◽  
Binding Site ◽  
Calcium Binding ◽  
Human Breast Cancer ◽  
Structural Changes ◽  
Human Breast Cancer Cell ◽  
Human Breast ◽  
Calcium Binding Site ◽  
High Affinity

Human MMP-26 (matrix metalloproteinase-26) (also known as endometase or matrilysin-2) is a putative biomarker for human carcinomas of breast, prostate and other cancers of epithelial origin. Calcium modulates protein structure and function and may act as a molecular signal or switch in cells. The relationship between MMPs and calcium has barely been studied and is absent for MMP-26. We have investigated the calcium-binding sites and the role of calcium in MMP-26. MMP-26 has one high-affinity and one low-affinity calcium binding site. High-affinity calcium binding was restored at physiologically low calcium conditions with a calcium-dissociation constant of 63 nM without inducing secondary and tertiary structural changes. High-affinity calcium binding protects MMP-26 against thermal denaturation. Mutants of this site (D165A or E191A) lose enzymatic activity. Low-affinity calcium binding was restored at relatively high calcium concentrations and showed a Kd2 (low-affinity calcium-dissociation constant) value of 120 μM, which was accompanied with the recovery of enzymatic activity reversibly and tertiary structural changes, but without secondary structural rearrangements. Mutations at the low-affinity calcium-binding site (C3 site), K189E or D114A, induced enhanced affinity for the Ca2+ ion or an irreversible loss of enzymatic activity triggered by low-affinity calcium binding respectively. Mutation at non-calcium-binding site (V184D at C2 site) showed that C2 is not a true calcium-binding site. Observations from homology-modelled mutant structures correlated with these experimental results. A human breast cancer cell line, MDA-MB-231, transfected with wild-type MMP-26 cDNA showed a calcium-dependent invasive potential when compared with controls that were transfected with an inactive form of MMP-26 (E209A). Calcium-independent high invasiveness was observed in the K189E mutant MDA-MB-231 cell line.

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