The thumb's knuckle: Flexibility in the thumb subdomain of T7 RNA polymerase is revealed by the structure of a chimeric T7/T3 RNA polymerase

摘要: We have solved the structure of a chimeric T7/T3 RNA polymerase (RNAP) in an orthorhombic crystal by molecular replacement with T7 RNAP determined from monoclinic crystal. The protruding "thumb" subdomain appears very different these two crystals apparently because differences packing contacts made thumb subdomain. These observations support proposal that is flexible and can wrap around bound template to obstruct polymerase: dissociation during processive synthesis.