scholarly journals Structure of Escherichia coli dnaC. Identification of a cysteine residue possibly involved in association with dnaB protein.

1987 ◽  
Vol 262 (22) ◽  
pp. 10475-10480 ◽  
Author(s):  
N Nakayama ◽  
M W Bond ◽  
A Miyajima ◽  
J Kobori ◽  
K Arai
Keyword(s):  
Escherichia Coli ◽  
Cysteine Residue

Chemical Modifications of Escherichia coli Ribosomal Proteins S4, S7, and S8 in Regard to Their Capacity for Binding 16 S RNA

1974 ◽  
Vol 52 (11) ◽  
pp. 1038-1043 ◽  
Author(s):  
Gérald Lemieux
Keyword(s):  
Escherichia Coli ◽  
Ribosomal Proteins ◽  
Binding Capacity ◽  
Cysteine Residue ◽  
Amino Groups ◽  
Chemical Modifications ◽  
Specific Chemical ◽  
Rna Interaction ◽  
Rna Complex ◽  
Rna Complexes

Mild specific chemical modifications were used to test the possible role of cysteines, tyrosines, and amino groups of ribosomal proteins S4, S7, and S8 for binding to 16 S RNA (Escherichia coli). The single cysteine residue present in proteins S4 and S8 is not directly involved in the binding process with RNA. The protein S7 does not contain cysteine. Total nitration of tyrosines in S4, S7, and S8 abolishes the binding capacity of these proteins. However, when the modification is done with the preformed protein–RNA complexes, some protection occurs. Two amino groups could be reacted in free S8 as well as in an S8–RNA complex. This modification does not influence protein–RNA interaction. Proteins S4, S7, and S8 in Regard to Their Capacity for Binding 16 S RNA. Can. J. Biochem. 52, modified. A new method for the stoichiometric determination of single protein–RNA complexes is presented.

scholarly journals Identification of a cysteine residue as the binding site for the dipyrromethane cofactor at the active site of Escherichia coli porphobilinogen deaminase

FEBS Letters ◽  
1988 ◽  
Vol 235 (1-2) ◽  
pp. 189-193 ◽  
Author(s):  
Peter M. Jordan ◽  
Martin J. Warren ◽  
Howard J. Williams ◽  
Neal J. Stolowich ◽  
Charles A. Roessner ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Binding Site ◽  
Active Site ◽  
Cysteine Residue ◽  
Porphobilinogen Deaminase

scholarly journals Structural and functional roles of Cys-238 and Cys-295 in Escherichia coli phosphofructokinase-2

2003 ◽  
Vol 376 (1) ◽  
pp. 277-283 ◽  
Author(s):  
Mauricio BAEZ ◽  
Patricio H. RODRÍGUEZ ◽  
Jorge BABUL ◽  
Victoria GUIXÉ
Keyword(s):  
Escherichia Coli ◽  
Cysteine Residue ◽  
Active Species ◽  
Native Enzyme ◽  
Functional Roles ◽  
Allosteric Effector ◽  
Rapid Inactivation ◽  
Modified Enzyme ◽  
The One

Modification of Escherichia coli phosphofructokinase-2 (Pfk-2) with pyrene maleimide (PM) results in a rapid inactivation of the enzyme. The loss of enzyme activity correlates with the incorporation of 2 mol of PM/mol of subunit and the concomitant dissociation of the dimeric enzyme. The two modified residues were identified as Cys-238 and Cys-295. In the presence of the negative allosteric effector, MgATP, Cys-238 was the only modified cysteine residue. Kinetic characterization of the Cys-238-labelled Pfk-2 indicates that the enzyme is fully active, with the kinetic constants (Km, kcat) being almost identical to the ones obtained for the native enzyme. The modified enzyme is a monomer in the absence of ligands and, like the native enzyme, behaves as a tetramer in the presence of the nucleotide. However, in the presence of fructose-6-phosphate (fru-6-P) and ATP−4, the enzyme behaves as a dimer, suggesting that the monomers undergo re-association in the presence of the substrates and that the active species is a dimer. Modification of Pfk-2 with eosin-5-maleimide (EM) results in the labelling of Cys-295. This modified enzyme is inactive and is not able to bind to the allosteric effector, remaining as a dimer in its presence. Nonetheless, Cys-295-labelled Pfk-2 is able to bind to the substrate fru-6-P in an hyperbolic fashion with a Kd value that is 6-fold higher than the one determined for the native enzyme. These are the first residues to be implicated in the activity and/or structure of the Pfk-2.

Putative identification of an amphipathic α-helical sequence in hemolysin of Escherichia coli (HlyA) involved in transmembrane pore formation

2008 ◽  
Vol 389 (9) ◽  
Author(s):  
Angela Valeva ◽  
Isabel Siegel ◽  
Mark Wylenzek ◽  
Trudy M. Wassenaar ◽  
Silvia Weis ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Amino Acids ◽  
Pore Formation ◽  
Cysteine Residue ◽  
Binding Properties ◽  
Cysteine Scanning ◽  
Helix Structure ◽  
Cysteine Scanning Mutagenesis ◽  
Α Helix ◽  
Polarity Sensitive

AbstractEscherichia colihemolysin is a pore-forming protein belonging to the RTX toxin family. Cysteine scanning mutagenesis was performed to characterize the putative pore-forming domain of the molecule. A single cysteine residue was introduced at 48 positions within the sequence spanning residues 170–400 and labeled with the polarity-sensitive dye badan. Spectrofluorimetric analyses indicated that several amino acids in this domain are inserted into the lipid bilayer during pore formation. An amphipathic α-helix spanning residues 272–298 was identified that may line the aqueous pore. The importance of this sequence was highlighted by the introduction of two prolines at positions 284 and 287. Disruption of the helix structure did not affect binding properties, but totally abolished the hemolytic activity of the molecule.

scholarly journals Interplay between the Specific Chaperone-Like Proteins HybG and HypC in Maturation of Hydrogenases 1, 2, and 3 from Escherichia coli

2001 ◽  
Vol 183 (9) ◽  
pp. 2817-2822 ◽  
Author(s):  
Melanie Blokesch ◽  
Axel Magalon ◽  
August Böck
Keyword(s):  
Escherichia Coli ◽  
Complex Formation ◽  
Gene Product ◽  
Genetic Background ◽  
Large Subunit ◽  
Cysteine Residue ◽  
Maturation Process ◽  
Hydrogenase 3 ◽  
Hydrogenase 2

ABSTRACT The hybG gene product from Escherichia colihas been identified as a chaperone-like protein acting in the maturation of hydrogenases 1 and 2. It was shown that HybG forms a complex with the precursor of the large subunit of hydrogenase 2. As with HypC, which is the chaperone-like protein involved in hydrogenase 3 maturation, the N-terminal cysteine residue is crucial for complex formation. Introduction of a deletion into hybG abolished the generation of active hydrogenase 2 but only quantitatively reduced hydrogenase 1 activity since HypC could replace HybG in this function. In contrast, HybG could not take over the role of HypC in a ΔhypC genetic background. Overproduction of HybG, especially of the variants with the replaced N-terminal cysteine residue, strongly interfered with hydrogenase 3 maturation, apparently by titrating some other component(s) of the maturation machinery. The results indicate that the three hydrogenase isoenzymes not only are interacting at the functional level but are also interconnected during the maturation process.

scholarly journals [3Fe-4S]↔[4Fe-4S] cluster interconversion in Desulfovibrio africanus ferredoxin III: properties of an Asp14→Cys mutant

1997 ◽  
Vol 323 (1) ◽  
pp. 95-102 ◽  
Author(s):  
Johanneke L. H. BUSCH ◽  
Jacques L. BRETON ◽  
Barry M. BARTLETT ◽  
Fraser A. ARMSTRONG ◽  
Richard JAMES ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Cluster Analysis ◽  
Spin State ◽  
Magnetic Circular Dichroism ◽  
Cysteine Residue ◽  
Mutant Protein ◽  
Native Protein ◽  
Ground Spin State ◽  
Aspartate Residue ◽  
Reduced State

The 8Fe ferredoxin III from Desulfovibrio africanus is a monomeric protein which contains two [4Fe-4S]2+/1+ clusters, one of which is labile and can readily and reversibly lose one Fe under oxidative conditions to yield a [3Fe-4S]1+/0 cluster. This 4Fe cluster has an S = 3/2 ground spin state instead of S = 1/2 in the reduced +1 state [George, Armstrong, Hatchikian and Thomson (1989) Biochem. J.264, 275-284]. The co-ordination to this cluster is unusual in that an aspartate (Asp14, D14) is found where a cysteine residue normally occurs. Using a mutant protein obtained from the overexpression in Escherichia coli of a synthetic gene in which Asp14, the putative ligand to the removable Fe, has been changed to Cys, we have studied the cluster interconversion properties of the labile cluster. Analysis by EPR and magnetic-circular-dichroism spectroscopies showed that the Asp14 → Cys (D14C) mutant contains two [4Fe-4S]2+/1+ clusters, both with S = 1/2 in the reduced state. Also, unlike in native 8Fe D. africanus ferredoxin III, the 4Fe ↔ 3Fe cluster interconversion reaction was found to be sluggish and did not go to completion. It is inferred that the reversibility of the reaction in the native protein is due to the presence of the aspartate residue at position 14 and that this residue might protect the [3Fe-4S] cluster from further degradation.

Role of Cal, the colicin A lysis protein, in two steps of colicin A release and in the interaction with colicin A–porin complexes

Microbiology ◽  
2004 ◽  
Vol 150 (11) ◽  
pp. 3867-3875 ◽  
Author(s):  
Danièle Cavard
Keyword(s):  
Escherichia Coli ◽  
Insoluble Fraction ◽  
Cysteine Residue ◽  
Secretion System ◽  
Type Iv Secretion ◽  
Type Iv Secretion System ◽  
Temperature Sensitive ◽  
Type Iv ◽  
Definition Of

Release of colicin A was studied in Escherichia coli cells that differed in expressing the colicin A lysis protein (Cal). Pools of released and unreleased colicin A were harvested throughout colicin A induction. The amount of colicin A in each pool varied with the time of induction, allowing the definition of two sequential steps in colicin A release, one of which was dependent on Cal. Each step of colicin A release was differently affected in cells containing Cal mutants in which the N-terminal cysteine residue was substituted by either proline or threonine, preventing them from being acylated and matured. These Cal mutants were only observed in degP cells, indicating that the DegP protease cleaved the unacylated precursor of Cal. Cal was found in the insoluble fraction of the pools of released and unreleased colicin A together with the hetero-oligomers of colicin A and porins (colicins Au). The biogenesis of colicins Au was studied in temperature-sensitive secA and secY strains and found to be Sec-independent, indicating that they are formed by newly synthesized colicin A binding to mature porins already incorporated in the outer membrane. Cal is a lipoprotein similar to VirB7, a constituent of the type IV secretion system. It would interact with colicins Au to constitute the colicin A export machinery.

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