Thermodynamics of a protein acylation: activation of Escherichia coli hemolysin toxin.

HlyC, hemolysin-activating lysine-acyltransferase, catalyses the acylation (from acyl-acyl carrier protein [ACP]) of Escherichia coli prohemolysin (proHlyA) on the epsilon-amino groups of specific lysine residues, 564 and 690 of the 1024 amino acid primary structure, to form hemolysin (HlyA). Isothermal titration calorimetry was used to measure the thermodynamic properties of the protein acylation of proHlyA-derived structures, altered by substantial deletions and separation of the acylation sites into two different peptides and site directed mutation analyses of acylation sites. Acylation of proHlyA-derived proteins catalyzed by HlyC was overall an exothermic reaction driven by a negative enthalpy.

Activation of hemolysin toxin: relationship between two internal protein sites of acylation.

HlyC, hemolysin-activating lysine acyltransferase, catalyzes the acylation (from acyl-ACP) of Escherichia coli prohemolysin (proHlyA) on the epsilon-amino groups of specific lysine residues, Lys564 and Lys690 of the 1024-amino acid primary structure, to form hemolysin (HlyA). The amino acid sequences flanking the two acylation sites are not homologous except that each has a glycine residue immediately preceding the lysine which is acylated; there are, however, numerous GK sequences throughout proHlyA that are not acylation sites. The substrate specificity of acylation was examined.

Amino acid residues of Escherichia coli acyl carrier protein involved in heterologous protein interactions.

Acyl carrier protein (ACP) is a small, highly conserved protein with an essential role in a myriad of reactions throughout lipid metabolism in plants and bacteria where it interacts with a remarkable diversity of proteins. The nature of the proper recognition and precise alignment between the protein moieties of ACP and its many interactive proteins is not understood. Residues conserved among ACPs from numerous plants and bacteria were considered as possibly being crucial to ACP's function, including protein-protein interaction, and a method of identifying amino acid residue clusters of high hydrophobicity on ACP's surface was used to estimate residues possibly involved in specific ACP-protein interactions.

Insights into the catalytic mechanism of HlyC, the internal protein acyltransferase that activates Escherichia coli hemolysin toxin.

Hemolysin, a toxic protein secreted by pathogenic Escherichia coli, is converted from nontoxic prohemolysin, proHlyA, to toxic hemolysin, HlyA, by an internal protein acyltransferase, HlyC. Acyl-acyl carrier protein (ACP) is the essential acyl donor. The acyltransferase reaction proceeds through two partial reactions and entails formation of a reactive acyl-HlyC intermediate [Trent, M.

HlyC, the internal protein acyltransferase that activates hemolysin toxin: roles of various conserved residues in enzymatic activity as probed by site-directed mutagenesis.

Hemolysin, a toxic protein produced by pathogenic Escherichia coli, is one of a family of homologous toxins and toxin-processing proteins produced by Gram-negative bacteria. HlyC, an internal protein acyltransferase, converts it from nontoxic prohemolysin to toxic hemolysin. Acyl-acyl carrier protein is the essential acyl donor.