Identification of N-terminal acetylation of recombinant human prothymosin α in Escherichia coli

• Published in: Biochimica et biophysica acta Vol. 1760; no. 8; pp. 1241 - 1247
• Main Authors: Wu, Jun, Chang, Shaohong, Gong, Xing, Liu, Dianxin, Ma, Qingjun
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01-08-2006
• Subjects: Acetylation; Amino Acid Sequence; Chromatography, High Pressure Liquid; Electrophoresis, Polyacrylamide Gel; Escherichia coli; Escherichia coli - metabolism; Humans; Molecular Sequence Data; N-terminal acetylation; prokaryote; Protein Precursors - chemistry; Protein Precursors - metabolism; prothymosin α; Recombinant Proteins - chemistry; Recombinant Proteins - metabolism; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Thymosin - analogs & derivatives; Thymosin - chemistry; Thymosin - metabolism; prokaryote; Escherichia coli; prothymosin α; N-terminal acetylation
• ISSN: 0304-4165; 0006-3002; 1872-8006
• DOI: 10.1016/j.bbagen.2006.04.001

Functional modification of protein through N-terminal acetylation is common in eukaryotes but rare in prokaryotes. Prothymosin α is an essential protein in immune stimulation and apoptosis regulation. The protein is N-terminal acetylated in eukaryotes, but similar modification has never been found in recombinant protein produced in prokaryotes. In this study, two mass components of recombinant human prothymosin α expressed in
Escherichia coli were identified and separated by RP-HPLC. Mass spectrometry of the two components showed that one of them had a 42 Da mass increment as compared with the theoretical mass of human prothymosin α, which suggested a modification of acetylation. The mass of another one was equal to that of the theoretical one. Peptides mass spectrometry of the modified component showed that the 42-Da mass increment occurred in the N-terminal peptide domain, and MS/MS peptide sequencing of the N-terminal peptide found that the acetylated modification occurred at the N-terminal serine residue. So, part of the recombinant human prothymosin α produced by
E. coli was N-terminal acetylated. This finding adds a new clue for the mechanism of acetylated modification in prokaryotes, and also suggested a new method for production of N-terminal modificated prothymosin α and thymosin α1.