Figure 6

NusA functions during transcription regulation. (a-c) Interaction surfaces of λQ (λQ in surface representation, gray, PDB ID: 4MO1). Residues affected by NusA-NTD binding are colored in green (a; this study), NusA-AR2 binding in blue (b; this study), and βFTH and DNA binding in yellow and red, respectively (c; data taken from¹⁴). (d) Model of the autoinhibited state of NusA. NusA-AR2 (PDB ID: 1WCN, blue) is in ribbon, NusA-SKK (PDB ID: 5LM9, green) in surface representation, NusA-NTD and NusA-AR1 are depicted as green ellipsoids. The panel shows a magnification of the boxed region with W490 and F491 of NusA-AR2 as red sticks. (e) Scheme of possible roles of NusA. NusA-AR2 is shown in ribbon representation (PDB ID: 1WCN, blue) with W490 and F491 as red sticks, all other NusA domains and proteins are shown as ellipsoids and labeled. Selected RNAP binding sites are depicted in ribbon representation and labeled. Blue arrows indicate interactions of NusA-AR2 with other transcription factors, gray arrows show interactions with RNAP (the interaction of SuhB with RNAP requires further investigation and is displayed as dashed arrow). β’ clamp helices, β’CH. The PyMOL Molecular Graphics System (Version 1.7, Schrödinger, LLC.; https://pymol.org) was used for visualization of protein structures.