Negative allosteric regulation ofEnterococcus faecalissmall alarmone synthetase RelQ by single-stranded RNA.
The alarmone nucleotides guanosine pentaphosphate (pppGpp) and tetraphosphate (ppGpp), collectively referred to as (p)ppGpp, are key regulators of bacterial growth, stress adaptation, pathogenicity, and antibiotic tolerance. We show that the tetrameric small alarmone synthetase (SAS) RelQ from the Gram-positive pathogenEnterococcus faecalisis a sequence-specific RNA-binding protein. RelQ's enzymatic and RNA binding activities are subject to intricate allosteric regulation. (p)ppGpp synthesis is potently inhibited by the binding of single-stranded RNA. Conversely, RelQ's enzymatic activity destabilizes the RelQ:RNA complex. pppGpp, an allosteric activator of the enzyme, counteracts the effect of RNA. Tetramerization of RelQ is essential for this regulatory mechanism, because both RNA binding and enzymatic activity are abolished by deletion of the SAS-specific C-terminal helix 5α. The interplay of pppGpp binding, (p)ppGpp synthesis, and RNA binding unites two archetypal regulatory paradigms within a single protein. The mechanism is likely a prevalent but previously unappreciated regulatory switch used by the widely distributed bacterial SAS enzymes.
Institute of Technology, University of Tartu, 50411 Tartu, Estonia.
Jelena
J
Beljantseva
Institute of Technology, University of Tartu, 50411 Tartu, Estonia.
Pavel
P
Kudrin
Department of Molecular Biology, Umeå University, SE-901 87 Umea, Sweden.|Laboratory for Molecular Infection Medicine Sweden, Umeå University, SE-901 87 Umea, Sweden.
Liis
L
Andresen
Department of Molecular Biology, Umeå University, SE-901 87 Umea, Sweden.
Victoria
V
Shingler
Department of Molecular Biology, Umeå University, SE-901 87 Umea, Sweden.
Gemma C
GC
Atkinson
Institute of Technology, University of Tartu, 50411 Tartu, Estonia.
Tanel
T
Tenson
Institute of Technology, University of Tartu, 50411 Tartu, Estonia; vasili.hauryliuk@umu.se.|Department of Molecular Biology, Umeå University, SE-901 87 Umea, Sweden.|Laboratory for Molecular Infection Medicine Sweden, Umeå University, SE-901 87 Umea, Sweden.
Vasili
0000-0003-2389-5057
V
Hauryliuk
D000494:Allosteric Regulation; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism; D001483:Base Sequence; D001665:Binding Sites; D013293:Enterococcus faecalis / Q000737:chemistry / Q000201:enzymology*; D015964:Gene Expression Regulation, Bacterial; D006158:Guanosine Pentaphosphate / Q000378:metabolism*; D008025:Ligases / Q000737:chemistry* / Q000378:metabolism*; D008958:Models, Molecular; D011485:Protein Binding; D055503:Protein Multimerization; D012329:RNA, Bacterial / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism*; D013379:Substrate Specificity
D001426:Bacterial Proteins; D012329:RNA, Bacterial; D012333:RNA, Messenger; D006158:Guanosine Pentaphosphate; D008025:Ligases
(p)ppGpp; RNA–protein interaction; allosteric regulation; nucleotide signaling; stringent response