期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2005
卷号：102
期号：48
页码：17320-17325
DOI：10.1073/pnas.0506599102
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：RsbR is a regulator of {sigma}B, the RNA polymerase {sigma} factor subunit responsible for transcribing the general stress response genes when environmental stress is imposed on Bacillus subtilis. The C-terminal domain of RsbR and its paralogues is a substrate for the kinase function of another {sigma}B regulator, RsbT, but the amino acid sequence of the N-terminal domain of RsbR does not reveal any obvious biochemical function. RsbR, its paralogues, and other regulators of {sigma}B, including RsbS and RsbT, form large signaling complexes, called stressosomes. We have determined and present here the crystal structure of the N-terminal domain of RsbR. Unexpectedly, this structure belongs to the globin fold superfamily, but there is no bound cofactor. The globin domain from globin-coupled sensory systems replaces the N-terminal domain of RsbR in some bacteria, indicating a common genetic ancestry for RsbR and the globin family. We suggest that the globin fold has been "recycled" in RsbR and that one more activity can be included in the repertoire of globin functions, namely the ability to bind signaling macromolecules such as RsbT.
