Autoinducer synthase modulating compounds and uses therefore

Abstract

Provided are compositions and methods useful for modulating the activity of autoinducer synthase catalysts. A method for identifying modulators of the autoinducer synthesis reaction is also provided. Such modulators are useful for controlling bacterial growth and can be used for therapeutic treatment of bacterial infections particularly in immunocompromised subjects. They are also useful in treating disease states associated with autoinducer synthesis and biofilm development.

What is claimed is:  
     
         1 . A method for modulating the activity of an autoinducer synthase molecule comprising: 
 providing an effective amount of a compound capable of modulating the binding of a substrate to the homoserine lactone substrate binding site of the autoinducer synthase,    thereby modulating the activity of the autoinducer synthase molecule.    
     
     
         2 . The method of  claim 1 , wherein the said autoinducer synthase molecule is selected from the group of bacterial quorum system autoinducer synthase molecules consisting of LuxI, AinS, LucM, LasI, RhlI, PhzI, TraI, CarI, HsII, EsaI, EagI, YenI, SwrI, and AhyI.  
     
     
         3 . The method of  claim 2 , wherein the said autoinducer synthase is RhlI.  
     
     
         4 . The method of any of claims  1 - 3 , wherein said compound inhibits the binding of said substrate to the homoserine lactone substrate binding site of the autoinducer synthase.  
     
     
         5 . The method of  claim 1 , wherein the said compound promotes the binding of said substrate to the homoserine lactone substrate binding site on the autoinducer synthase.  
     
     
         6 . The method of  claim 1 , wherein the said substrate is S-adenosyl methionine.  
     
     
         7 . The method of  claim 4 , wherein the said compound is a thio derivative of a purine nucleotide.  
     
     
         8 . The method of  claim 7 , wherein the said compound is an alkylated thio derivative of a purine nucleotide.  
     
     
         9 . The method of  claim 8 , wherein the said derivative is S-adenosyl homocysteine.  
     
     
         10 . The method of  claim 8 , wherein the said derivative is S-adenosyl cysteine.  
     
     
         11 . The method of  claim 8 , wherein the said derivative is 5′-methylthioadenosine.  
     
     
         12 . The method of  claim 4 , wherein the said compound is sinefungin.  
     
     
         13 . The method of  claim 1 , wherein the said modulation of the autoinducer synthase molecule activity occurs in vivo.  
     
     
         14 . The method of  claim 1 , wherein the said modulation of the autoinducer synthase molecule activity occurs in vitro.  
     
     
         15 . A method of selecting a compound capable of modulating the activity of the autoinducer synthase molecule comprising: 
 providing an effective amount of a test compound; and    determining whether the activity of the autoinducer synthase molecule is modulated; and    selecting the compound which modulates the activity of the autoinducer synthase molecule.    
     
     
         16 . The method of  claim 15 , further comprising determining the extent of the modulation of the autoinducer synthase molecule by the said compound.  
     
     
         17 . The method of  claim 16  wherein the extent to which the activity of the autoinducer synthase molecule is modulated is determined by: 
 providing a sufficient amount of a labeled homoserine lactone substrate;  
 allowing the reaction to proceed to completion; and  
 determining the extent of conversion of the labeled homoserine lactone substrate to a homoserine lactone product.  
 
     
     
         18 . The method of  claim 17 , wherein, the homoserine lactone substrate is S-adenosylmethionine.  
     
     
         19 . A method for producing a highly active bacterial recombinant autoinducer synthase molecule comprising: 
 introducing DNA encoding said bacterial autoinducer synthase molecule into a bacterial host cell of the same species such that the autoinducer synthase molecule is overexpressed,    thereby producing the highly active recombinant autoinducer synthase molecule.    
     
     
         20 . The method of  claim 19 , wherein the said purity of the autoinducer synthase is in the range of from about 50% to about 100% pure.  
     
     
         21 . An autoinducer synthase molecule produced by the method of  claim 19 .  
     
     
         22 . An amino acid sequence of SEQ ID NO. 1 comprising amino acids 24-104.  
     
     
         23 . The amino acid sequence of  claim 22  comprising acids 24-73.  
     
     
         24 . The amino acid sequence of  claim 22  comprising Arginine 24, Glutamic Acid 46, Aspartic Acid 48 and Glutamic Acid 101.  
     
     
         25 . A method for modulating the formation of bacterial quorum system autoinducers comprising: 
 providing an effective amount of a compound capable of modulating the binding of a substrate to the homoserine lactone substrate binding site of the autoinducer synthase,    thereby modulating the formation of bacterial quorum system autoinducers.    
     
     
         26 . A method for modulating bacterial biofilm development comprising: 
 providing an effective amount of a compound capable of modulating the binding of a substrate to the homoserine lactone substrate binding site of an autoinducer synthase,    thereby modulating the development of bacterial biofilms.    
     
     
         27 . A method of inhibiting the infectivity of a pathogenic bacteria in a subject comprising administering a therapeutically effective amount of an autoinducer synthase blocker, such that the infectivity of a pathogenic bacteria is inhibited.  
     
     
         28 . A method of treating an immunocompromised individual by administering a therapeutically effective amount of an autoinducer synthase blocker to an immunocompromised individual, such that treatment occurs.  
     
     
         29 . A therapeutic composition comprising an autoinducer synthase blocker and a pharmaceutically acceptable carrier.  
     
     
         30 . The therapeutic composition of  claim 29 , wherein the autoinducer synthase blocker is a molecule which inhibits the autoinducer synthase activity of RhlI.  
     
     
         31 . A method of treating a subject for a disease state associated with biofilm development comprising administering a therapeutically effective amount of an autoinducer synthase blocker, such that biofilm development is inhibited.  
     
     
         32 . A method for treating a subject for a state associated with autoinducer synthesis comprising administering an effective amount of an autoinducer synthase blocker such that treatment occurs.  
     
     
         33 . A purified autoinducer synthase molecule which is at least about 50% pure and being biologically active.  
     
     
         34 . The autoinducer synthase molecule of  claim 33  which is about 95% pure.  
     
     
         35 . The autoinducer synthase molecule of  claim 33  which is RhlI.  
     
     
         36 . A biologically active autoinducer synthase molecule substantially free of other contaminants.  
     
     
         37 . The autoinducer synthase molecule of  claim 33  or  36  which is substantially free of inclusion bodies.  
     
     
         38 . A highly soluble autoinducer synthase molecule having biological activity.