Open AccessA cytotoxic ribonuclease which specifically cleaves four isoaccepting arginine tRNAs at their anticodon loops
Author(s) -
Kozo Tomita,
Tetsuhiro Ogawa,
Tohru Uozumi,
Kimitsuna Watanabe,
Masaki Hara
Publication year - 2000
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.140213797
Subject(s) - colicin , transfer rna , biology , ribosome , biochemistry , ribonuclease , protein biosynthesis , escherichia coli , cleavage (geology) , rna , amino acid , arginine , in vitro , histidine , microbiology and biotechnology , paleontology , fracture (geology) , gene
Colicin D has long been thought to stop protein synthesis in infectedEscherichia coli cells by inactivating ribosomes, just like colicin E3. Here, we show that colicin D specifically cleaves tRNAsArg including four isoaccepting molecules bothin vivo andin vitro . The cleavage occursin vitro between positions 38 and 39 in an anticodon loop with a 2′,3′-cyclic phosphate end, and is inhibited by a specific immunity protein. Consistent with the cleavage of tRNAsArg , the RNA fraction of colicin-treated cells significantly reduced the amino acid-accepting activity only for arginine. Furthermore, we generated a single mutation of histidine in the C-terminal possible catalytic domain, which caused the loss of the killing activityin vivo together with the tRNAArg -cleaving activity bothin vivo andin vitro . These findings show that colicin D directly cleaves cytoplasmic tRNAsArg , which leads to impairment of protein synthesis and cell death. Recently, we found that colicin E5 stops protein synthesis by cleaving the anticodons of specific tRNAs for Tyr, His, Asn, and Asp. Despite these apparently similar actions on tRNAs and cells, colicins D and E5 not only exhibit no sequence homology but also have different molecular mechanisms as to both substrate recognition and catalytic reaction.