New peptide chain release factor B, useful for improving recombinant protein production in bacteria, also a more active variant and related nucleic acids, vectors and cells, accelerates release of proteins from the ribosome

摘要

Factor PrfB (peptide chain release factor B) having an amino acid (aa) sequence that is at least 93% identical with a 366 aa sequence (2), reproduced, is new. Independent claims are also included for the following: (1) variant (A) of PrfB that has, at least one of positions homologous to positions 71 and 100 of sequence (2), Asn or Ser, respectively, particularly both; (2) factor PrfB encoded by a nucleic acid (I) that is at least 80% identical with a 1102 base pairs (bp) sequence (1), reproduced; (3) (I) as new; (4) vector that contains (I); (5) cell, or its derivatives, obtained by transformation with (I); (6) method for preparing PrfB and its variants, using (I), the vector of (4) or the cell of (5); and (7) method for preparing proteins (X) by culturing bacteria in which PrfB activity is higher than normal.