RimJ is responsible for N(alpha)-acetylation of thymosin alpha1 in Escherichia coli.
N(alpha)-Acetylation is one of the most common protein modifications in eukaryotes but a rare event in prokaryotes. Some endogenously N(alpha)-acetylated proteins in eukaryotes are frequently reported not to be acetylated or only very partially when expressed in recombinant Escherichia coli. Thymosin alpha1 (Talpha1), an N(alpha)-acetylated peptide of 28 amino acids, displays a powerful general immunostimulating activity. Here, we revealed that a fusion protein of thymosin alpha1 and L12 is partly N(alpha)-acetylated in E. coli. Through deletion of some N(alpha)-acetyltransferases by Red recombination, we found that, when rimJ is disrupted, the fusion protein is completely unacetylated. The relationship of rimJ and N(alpha)-acetylation of Talpha1 was further investigated by gene rescue and in vitro modification. Our results demonstrate that N(alpha)-acetylation of recombinant Talpha1-fused protein in E. coli is catalyzed by RimJ and that fully acetylated Talpha1 can be obtained by co-expressing with RimJ. This is the first description that an ectopic protein acetylation in bacterial expression systems is catalyzed by RimJ, a known prokaryotic N(alpha)-acetyltransferase.
Institute of Biotechnology, Academy of Military Medical Sciences, Beijing 100071, People's Republic of China. fanghongqing@vip.sina.com
Hongqing
H
Fang
Xu
X
Zhang
Lin
L
Shen
Xinxi
X
Si
Yuantao
Y
Ren
Hongmei
H
Dai
Shulong
S
Li
Changlin
C
Zhou
Huipeng
H
Chen
D000107:Acetylation; D000123:Acetyltransferases / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D012269:Ribosomal Proteins / Q000235:genetics / Q000378:metabolism*; D000077596:Thymalfasin; D013947:Thymosin / Q000031:analogs & derivatives* / Q000378:metabolism
D029968:Escherichia coli Proteins; D012269:Ribosomal Proteins; C077567:RimJ protein, E coli; D013947:Thymosin; D000123:Acetyltransferases; D000077596:Thymalfasin