?, a new subunit of RNA polymerase found in gram-positive bacteria.

ABSTRACT: RNA polymerase in bacteria is a multisubunit protein complex that is essential for gene expression. We have identified a new subunit of RNA polymerase present in the high-A+T Firmicutes phylum of Gram-positive bacteria and have named it ?. Previously ? had been identified as a small protein (?1) that copurified with RNA polymerase. We have solved the structure of ? by X-ray crystallography and show that it is not an ? subunit. Rather, ? bears remarkable similarity to the Gp2 family of phage proteins involved in the inhibition of host cell transcription following infection. Deletion of ? shows no phenotype and has no effect on the transcriptional profile of the cell. Determination of the location of ? within the assembly of RNA polymerase core by single-particle analysis suggests that it binds toward the downstream side of the DNA binding cleft. Due to the structural similarity of ? with Gp2 and the fact they bind similar regions of RNA polymerase, we hypothesize that ? may serve a role in protection from phage infection.

SUBMITTER: Keller AN 

PROVIDER: S-EPMC4187704 | biostudies-literature | 2014 Oct

REPOSITORIES: biostudies-literature