Fig 1. Domain architecture of Sa-Rel, Sa-Reltrunc, Sa-RelQ and Sa-RelP.
Schematic representation of domain structure of the Rel, RelQ and RelP proteins encoded by S. aureus. Protein lengths in amino acids (aa) are shown. The N-terminal domain of Sa-Rel comprises the HD and SYNTH domains, respectively responsible for alarmone hydrolysis and synthesis. The regulatory C-terminal domain (CTD) of Sa-Rel contains four conserved sub-domains/motifs: a ThrRS, GTPase, and SpoT (TGS) domain; an alpha helical domain (Helical); a conserved cysteine (CC) domain, also known as a (zinc-finger domain (ZFD), and an aspartokinase, chorismate mutase and TyrA (ACT) domain, which is also known as a ribosome recognition motif (RRM). The Sa-Reltrunc protein lacks the entire regulatory CTD. The Sa-RelQ and Sa-RelP proteins only contain the SYNTH domain.