┌──────────────────── Escherichia coli M718   
 ┌───────────────────┴──────────────────── Escherichia coli B185   
┌┴──────────────────── Escherichia coli TA206   
┤┌──────────────────── Escherichia coli 042 (5)  
└┤ ┌──────────────────── Escherichia coli NC101 (1)  
 │┌┴──────────────────── Escherichia coli H299   
 └┤ ┌─ Escherichia coli O127:H6 str. E2348/69   
  │┌┴──────────────────── Escherichia coli APEC O1 (6)  
  └┤┌─ Escherichia coli 2362-75 (23)  
   └┤┌──────────────────── Escherichia coli SE15   
    └┤                    ┌─ Escherichia coli 1044A (26)  
     │                   ┌┴─ Escherichia coli O157:H7 str. EC4486   
     └───────────────────┤                    ┌──────────────────── Escherichia coli H591 (1)  
                         └───────────────────┬┴──────────────────── Escherichia coli B str. REL606 (3)  
                                             └┬─ Escherichia coli B088 (2)  
                                              └┬─ Escherichia coli K12 (45)  
                                               └┬──────────────────── Escherichia coli 1827-70   
                                                └──────────────────── Escherichia coli B171 (4)  
  

  
Tryptophan synthase beta chain (EC 4.2.1.20)
 (18)