Articles in 2014

Enzymes that alter nucleosome structure or position are at the very center of gene and genome regulation, and understanding how, and to what extent, these diverse activities collaborate and control each other to shape the genome for dynamic regulation is a major challenge. A new study provides an important step in this direction by illustrating the cooperative nature of ATP-dependent chromatin-remodeling systems in mammalian cells.

Every RNA polymerase II transcript receives a 5′-end 7-methylguanosine (m⁷G) cap, which is rapidly bound by the nuclear cap–binding complex (CBC). Two recent studies now reveal that the CBC associates with a variety of effector proteins that enable it to interrogate nascent RNA, discriminating between distinct RNA subclasses and routing them either toward distinct maturation pathways or toward decay. Thus, the CBC has an early role in policing cellular RNA.

DNA replication begins with prereplication-complex formation at origins and is followed by helicase activation to unwind DNA at the replication fork. This Perspective compares bacterial DnaB and eukaryotic MCM2–7 helicase-loading mechanisms and discusses emerging data supporting current models of how two MCM2–7 complexes are loaded to form a double hexamer.

Functional analyses of the ABC-F protein YjjK (EttA) suggest that it acts as a sensor of cellular energy and controls entry into the translational elongation cycle. Using cryo-EM and single-molecule FRET, EttA is shown to bind the ribosomal E site and engage both the L1 stalk and P-site tRNA to restrain ribosomal dynamics.

Although ABC-F proteins represent a ubiquitously distributed type of ATP-binding cassette (ABC) family member across phyla, their biological functions remain poorly characterized. A new study now shows that the bacterial ABC-F protein YjjK (EttA) gates ribosome entry into the translational cycle in an energy-dependent manner.