first type II K-homology (KH) RNA-binding domain found in transcription termination/antitermination protein NusA and similar proteins
NusA, also called N utilization substance protein A or transcription termination/antitermination L factor, is an essential multifunctional transcription elongation factor that participates in both transcription termination and antitermination. NusA anti-termination function plays an important role in the expression of ribosomal rrn operons. During transcription of many other genes, NusA-induced RNA polymerase pausing provides a mechanism for synchronizing transcription and translation. In prokaryotes, the N-terminal RNA polymerase-binding domain (NTD) is connected through a flexible hinge helix to three globular domains, the S1 and two K-homology (KH), KH1 and KH2. The KH domains of NusA belong to the type II KH RNA-binding domain superfamily. This model corresponds to the first KH domain of NusA and similar proteins.