TstI, a Type II restriction-modification protein with DNA recognition, cleavage and methylation functions in a single polypeptide.

ABSTRACT: Type II restriction-modification systems cleave and methylate DNA at specific sequences. However, the Type IIB systems look more like Type I than conventional Type II schemes as they employ the same protein for both restriction and modification and for DNA recognition. Several Type IIB proteins, including the archetype BcgI, are assemblies of two polypeptides: one with endonuclease and methyltransferase roles, another for DNA recognition. Conversely, some IIB proteins express all three functions from separate segments of a single polypeptide. This study analysed one such single-chain protein, TstI. Comparison with BcgI showed that the one- and the two-polypeptide systems differ markedly. Unlike the heterologous assembly of BcgI, TstI forms a homotetramer. The tetramer bridges two recogniti

SUBMITTER: Smith RM 

PROVIDER: S-EPMC4027205 | biostudies-literature | 2014 May

REPOSITORIES: biostudies-literature