Methods and compositions for secretion of heterologous polypeptides

Abstract

The instant invention discloses the unexpected result that mutant signal sequences with reduced translational strength provided essentially complete processing and high levels of expression of a polypeptide of interest as compared to wild type signal sequences, and that many mammalian polypeptides require a narrow range of translation levels to achieve maximum secretion. A set of signal sequence vectors provides a range of translational strengths for optimizing expression of a polypeptide of interest.

1 . A method of optimizing secretion of a heterologous polypeptide of interest in a cell comprising comparing the levels of expression of the polypeptide under control of a set of nucleic acid variants of a translation initiation region, wherein the set of variants represents a range of translational strengths, and determining the optimal translational strength for production of mature polypeptide, wherein the optimal translational strength is less than the translational strength of the wild-type translation initiation region.  
     
     
         2 . The method of  claim 1 , wherein the variants comprise nucleic acid variants of a secretion signal sequence.  
     
     
         3 . The method of  claim 2 , wherein the variant secretion signal sequences are variants of STII.  
     
     
         4 . The method of  claim 3 , wherein the STII variants are the following variants  
       
         
           
                 
                 
               
                     
                 
                   5′ TCTAGAGGTTGAGGTGATTTT ATG AAA AAG AAT ATC GCA TTT CTT CTT 
                     
                 
                     
                 
                   GCA TCT ATG TTC GTT TTT TCT ATT GCT ACA AAY GCS TAT GCM 3′ (SEQ ID NO:15); 
                 
                     
                 
                   5′ TCTAGAATT ATG AAA AAG AAT ATC GCA TTT CTT CTT GCA TCT ATG TTC 
                 
                     
                 
                   GTT TTT TCT ATT GCT ACA AAC GCG TAT GCM 3′ (SEQ ID NO:16); 
                 
                     
                 
                   5′ TCTAGAATT ATG AAG AAG AAT ATT GCG TTC CTA CTT GCC TCT ATG TTT 
                 
                     
                 
                   GTC TTT TCT ATA GCT ACA AAC GCG TAT GCM 3′ (SEQ ID NO:17); 
                 
                     
                 
                   5′ TCTAGAATT ATG AAG AAG AAT ATC GCA TTT CTT CTT GCA TCT ATG TTC 
                 
                     
                 
                   GTT TTT TCT ATT GCT ACA AAC GCG TAT GCM 3′ (SEQ ID NO:18); 
                 
                     
                 
                   5′ TCTAGAATT ATG AAA AAA AAC ATC GCA TTT CTT CTT GCA TCT ATG TTC 
                 
                     
                 
                   GTT TTT TCT ATT GCT ACA AAC GCG TAT GCM 3′ (SEQ ID NO:19); 
                 
                     
                 
                   5′ TCTAGAATT ATG AAA AAA AAC ATT GCC TTT CTT CTT GCA TCT ATG TTC 
                 
                     
                 
                   GTT TTT TCT ATT GCT ACA AAC GCG TAT GCM 3′ (SEQ ID NO:20); 
                 
                     
                 
                   5′ TCTAGAATT ATG AAG AAA AAC ATC GCT TTT CTT CTT GCA TCT ATG TTC 
                 
                     
                 
                   GTT TTT TCT ATT GCT ACA AAC GCG TAT GCM 3′ (SEQ ID NO:21); 
                 
                     
                 
                   5′ TCTAGAATT ATG AAA AAG AAC ATA GCG TTT CTT CTT GCA TCT ATG TTC 
                 
                     
                 
                   GTT TTT TCT ATT GCT ACA AAC GCG TAT GCM 3′ (SEQ ID NO:22); and 
                 
                     
                 
                   5′ TCTAGAGGTTGAGGTGATTTT ATG AAA AAA AAC ATC GCA TTT CTT CTT 
                 
                     
                 
                   GCA TCT ATG TTC GTT TTT TCT ATT GCT ACA AAC GCG TAT GCM 3′ (SEQ ID NO:23).