Rna-binding protein

Abstract

A soluble RNA-binding protein having high binding ability is provided. The RNA-binding protein has an amino acid sequence represented by R1′-R1X-R2X-(R5X or R6Y)L-(R5X-R6Y)M-(R5X or R6Y)N-R7X-R8X-R8′, with each symbol meaning a specific amino acid sequence.

I claim: 
     
         1 . An RNA-binding protein having an amino acid sequence represented by R1′-R1X-R2X-(R5X or R6Y) L -(R5X-R6Y) M -(R5X or R6Y) N -R7X-R8X-R8′:
 wherein 
 R1X represents R1, R1(S12N), R1(S12C), R1(Q16E), or R1(Q16R), 
 R2X represents R2, R2(N12C), R2(N12S), R2(N12S, Q16E), or R2(N12S, Q16R), 
 R5X represents any one of R5, R5(C12S), R5(C12N), R5(C12S, Q16E), or R5(C12S, Q16R), 
 R6Y represents any one of R6, R6(N12C), R6(N12S), R6(N12S, Q16E), or R6(N12S, Q16R), 
 R7X represents R7, R7(S12C, E16Q), R7(E16Q), R7(S12N, E16Q), or R7(E16R), 
 R8X represents R8, R8(N12C), R8(N12S), R8(N12S, Q16E), or R8(N12S, Q16R). 
 S12N represents a substitution of a 12th amino acid S with N, 
 S12C represents a substitution of a 12th amino acid S with C, 
 N12C represents a substitution of a 12th amino acid N with C, 
 N125 represents a substitution of a 12th amino acid N with S, 
 C12N represents a substitution of a 12th amino acid C with N, 
 C12S represents a substitution of a 12th amino acid C with S, 
 Q16E represents a substitution of a 16th amino acid Q with E, 
 Q16R represents a substitution of a 16th amino acid Q with R, 
 E16Q represents a substitution of a 16th amino acid E with Q, 
 E16R represents a substitution of a 16th amino acid E with R, 
 L and N each independently represent 0 or 1, and M represents an integer of 2 or more, M preferably represents an integer of 2 to 20, more preferably an integer of 2 to 10, and even more preferably an integer of 2 to 5, and 
 each repeat corresponds to the following relevant amino acid sequence: 
 
       
         
           
                 
                 
               
                     
                   R1′: 
                 
                     
                   (SEQ ID NO: 9) 
                 
                     
                   GRSRLLEDFRNNRYPNLQLREIAG; 
                 
                     
                     
                 
                     
                   R1: 
                 
                     
                   (SEQ ID NO: 1) 
                 
                     
                   HIMEFSQDQHGSRFIQLKLERATPAERQLVFNEILQ; 
                 
                     
                     
                 
                     
                   R2: 
                 
                     
                   (SEQ ID NO: 2) 
                 
                     
                   AAYQLMVDVFGNYVIQKFFEFGSLEQKLALAERIRG; 
                 
                     
                     
                 
                     
                   R5: 
                 
                     
                   (SEQ ID NO: 5) 
                 
                     
                   QVFALSTHPYGCRVIQRILEHCLPDQTLPILEELHQ; 
                 
                     
                     
                 
                     
                   R6: 
                 
                     
                   (SEQ ID NO: 6) 
                 
                     
                   HTEQLVQDQYGNYVIQHVLEHGRPEDKSKIVAEIRG; 
                 
                     
                     
                 
                     
                   R7: 
                 
                     
                   (SEQ ID NO: 7) 
                 
                     
                   NVLVLSQHKFASNVVEKCVTHASRTERAVLIDEVCTMNDGPHS; 
                 
                     
                     
                 
                     
                   R8: 
                 
                     
                   (SEQ ID NO: 8) 
                 
                     
                   ALYTMMKDQYANYVVQKMIDVAEPGQRKIVMHKIRP; 
                 
                     
                     
                 
                     
                   R8′: 
                 
                     
                   (SEQ ID NO: 10) 
                 
                     
                   HIATLRKYTYGKHILAKLEKYYMKNGVDLG, 
                 
             
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
                
               
            
           
         
         wherein for at least one of the repeats R1X, R2X R5X R6Y, R7X, and R8X, 
         in a case in which a combination of a base recognized by the repeat and a downstream base adjacent thereto is A-A, the 13th amino acid of the corresponding repeat (i.e., an amino acid stacking between the two bases) is Tyr or His, 
         in a case in which the combination is G-A, U-A, C-A, U-C, or C-U, the 13th amino acid of the corresponding repeat (i.e., an amino acid stacking between the two bases) is Tyr, 
         in a case in which the combination is A-G, A-C, G-U, U-G, C-G, or G-C, the 13th amino acid of the corresponding repeat (i.e., an amino acid stacking between the two bases) is Arg, 
         in a case in which the combination is A-U or G-G, the 13th amino acid of the corresponding repeat (i.e., an amino acid stacking between the two bases) is Arg or His, in a case in which the combination is U-U, the 13th amino acid of the corresponding repeat (i.e., an amino acid stacking between the two bases) is Trp or Arg, and/or 
         in a case in which the combination is C-C, the 13th amino acid of the corresponding repeat (i.e., an amino acid stacking between the two bases) is Phe. 
       
     
     
         2 . A nucleic acid encoding the RNA-binding protein according to  claim 1 . 
     
     
         3 . A recombinant expression vector including the nucleic acid according to  claim 2 . 
     
     
         4 . A host cell including the recombinant expression vector according to  claim 3 .