Found: The Elusive ANTAR Transcription Antiterminator

Regulated transcription termination provides an efficient and responsive means to control gene expression [1]. Intrinsic terminators, which consist of an RNA stem-loop followed by a poly-U tract, catalyze termination by disrupting the RNA polymerase elongation complex [2]. In antitermination, an antiterminator stem-loop is mutually exclusive with the terminator stem-loop [1,3]. In different contexts, formation of the antiterminator stem-loop is governed by a translating ribosome [1], a ligand-binding riboswitch [4,5], or a signal-responsive RNA–binding protein [3]. This latter mechanism is illuminated by Ramesh et al. [6], who studied antitermination by a broadly distributed class of signal-responsive RNA-binding proteins containing the ANTAR domain.