| Primary Identifier | IPR006359 | Type | Family |
| Short Name | Tscrpt_elong_fac_GreA |
| description | Bacterial GreA and GreB promote transcription elongation by stimulating an endogenous, endonucleolytictranscript cleavage activity of the RNA polymerase (RNAP) [], allowing RNA transcription to continue past template-encoded arresting sites. GreA and GreB are sequence homologues and have homologues inevery known bacterial genome. GreA and GreB stimulate transcriptcleavage in different ways; GreA induces cleavage of 3'-RNA fragments 2-3 nt in length and can only preventthe formation of arrested complexes, whereas GreB induces cleavage of fragments up to 18 nt in length and canrescue pre-existing arrested complexes.The 2.2 Angstrom resolution crystal structure of Escherichia coli GreA comprises an N-terminalantiparallel α-helical coiled coil, and a C-terminal globular domain. While theC-terminal domain binds RNAP, theN-terminal coiled coil interacts with the transcript 3' end and is responsible for stimulating the transcriptcleavage reaction []. Functional differences between GreA and GreB correlate with the distribution of positively charged residues onone face of the N-terminal coiled coil.Because members of the family outside the Proteobacteria resemble GreA more closely than GreB, the GreB clade () forms a plausible outgroup and the remainder of the GreA/B family, included in this family, is designated GreA. In the Chlamydias and some spirochetes, the conserved region of these proteins is found as the C-terminal region of a much larger protein. |
