PMC:4502370 / 35851-36849 JSONTXT

{"target":"https://pubannotation.org/docs/sourcedb/PMC/sourceid/4502370","sourcedb":"PMC","sourceid":"4502370","source_url":"https://www.ncbi.nlm.nih.gov/pmc/4502370","text":"Arg79 is located within the 78QRATTP83 hexapeptide defined as essential by our deletion analysis; Arg79 forms a salt bridge to Glu150 (Figure 6A), which is located within the essential C-terminal pentapeptide 146WSVEE150. Yet alanine mutation of either Arg79 or Glu150 was benign in vivo (Figure 6B), signifying that this salt bridge is dispensable and that one or more other constituents of the 78QRATTP83 and 146WSVEE150 peptides must be essential for Rpo26 function. In the case of the proximal peptide segment, we suspect that the key contributions are the hydrogen bonds of the main-chain Thr82 and Tyr84 carbonyls to the terminal guanidinium nitrogens of the essential Arg136 side chain (Figure 6A). For the distal 146WSVEE150 peptide, the Trp146 side chain is the likely key constituent, insofar as Trp146 is the focus of an extensive interaction network; it forms a cation–π–cation sandwich between Arg79 and Arg136 (Figure 6A) and it donates a hydrogen bond from Nε to the Glu144-Oε1 atom.","tracks":[]}