Open AccessMutational analysis of Era, an essential GTP‐binding protein of Escherichia coli
Author(s) -
Shimamoto Toshi,
Inouye Masayori
Publication year - 1996
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1996.tb08025.x
Subject(s) - gtpase , gtp' , mutant , gtp binding protein regulators , small gtpase , biology , biochemistry , function (biology) , g protein , escherichia coli , gtpase activating protein , binding site , microbiology and biotechnology , signal transduction , gene , enzyme
Era is an essential GTP‐binding protein of an unknown function in Escherichia coli . On the basis of its sequence similarities to other GTP‐binding proteins such as E. coli EF‐Tu, EF‐G, IF2 and eukaryotic Ras proteins, it has been suggested that the Era function is activated by GTP binding, and that subsequent conversion of bound GTP to GDP by the intrinsic GTPase activity modulates its function. Two Era mutants, one dominant negative mutant (dE), which has a deletion mutation from Ala40 to Gly49, and the other non‐functional mutant (T42A/T43A), which has two substitution mutations, Thr42 to Ala and Thr43 to Ala, were analyzed for their abilities of GTP‐binding and GTPase activity. It was found that the dE mutant lost the GTP‐binding ability, while it still retained the GTPase activity. On the other hand, the T42A/T43A mutant retained both the GTP‐crosslinking and GTPase activities. However, the K m values for GTPase activity increased 5‐and 12‐fold for dE and T42A/T43A mutants, respectively. These results indicate that both the GTP‐binding and GTPase activities are important for the Era function.