TY - JOUR

T1 - Structural basis for (p)ppGpp synthesis by the Staphylococcus aureus small alarmone synthetase RelP

AU - Manav, Melek Cemre

AU - Beljantseva, Jelena

AU - Bojer, Martin S

AU - Tenson, Tanel

AU - Ingmer, Hanne

AU - Hauryliuk, Vasili

AU - Brodersen, Ditlev E

N1 - © 2018 by The American Society for Biochemistry and Molecular Biology, Inc.

PY - 2018

Y1 - 2018

N2 - The stringent response is a global reprogramming of bacterial physiology that renders cells more tolerant to antibiotics and induces virulence gene expression in pathogens in response to stress. This process is driven by accumulation of the intracellular alarmone guanosine-5'-di(tri)phosphate-3'-diphosphate ((p)ppGpp), which is produced by enzymes of the RelA SpoT homologue (RSH) family. The Gram-positive Firmicute pathogen,Staphylococcus aureus, encodes three RSH enzymes: a multidomain RSH (Rel) that senses amino acid starvation on the ribosome and two small alarmone synthetase (SAS) enzymes, RelQ (SAS1) and RelP (SAS2). InBacillus subtilis, RelQ (SAS1) was shown to form a tetramer that is activated by pppGpp and inhibited by single-stranded RNA, but the structural and functional regulation of RelP (SAS2) is unexplored. Here, we present crystal structures ofS. aureusRelP in two major functional states, pre-catalytic (bound to GTP and the non-hydrolyzable ATP analogue, adenosine 5'-(α,β-methylene)triphosphate (AMP-CPP)), and post-catalytic (bound to pppGpp). We observed that RelP also forms a tetramer, but unlike RelQ (SAS1), it is strongly inhibited by both pppGpp and ppGpp and is insensitive to inhibition by RNA. We also identified putative metal ion-binding sites at the subunit interfaces that were consistent with the observed activation of the enzyme by Zn2+ions. The structures reported here reveal the details of the catalytic mechanism of SAS enzymes and provide a molecular basis for understanding differential regulation of SAS enzymes in Firmicute bacteria.

AB - The stringent response is a global reprogramming of bacterial physiology that renders cells more tolerant to antibiotics and induces virulence gene expression in pathogens in response to stress. This process is driven by accumulation of the intracellular alarmone guanosine-5'-di(tri)phosphate-3'-diphosphate ((p)ppGpp), which is produced by enzymes of the RelA SpoT homologue (RSH) family. The Gram-positive Firmicute pathogen,Staphylococcus aureus, encodes three RSH enzymes: a multidomain RSH (Rel) that senses amino acid starvation on the ribosome and two small alarmone synthetase (SAS) enzymes, RelQ (SAS1) and RelP (SAS2). InBacillus subtilis, RelQ (SAS1) was shown to form a tetramer that is activated by pppGpp and inhibited by single-stranded RNA, but the structural and functional regulation of RelP (SAS2) is unexplored. Here, we present crystal structures ofS. aureusRelP in two major functional states, pre-catalytic (bound to GTP and the non-hydrolyzable ATP analogue, adenosine 5'-(α,β-methylene)triphosphate (AMP-CPP)), and post-catalytic (bound to pppGpp). We observed that RelP also forms a tetramer, but unlike RelQ (SAS1), it is strongly inhibited by both pppGpp and ppGpp and is insensitive to inhibition by RNA. We also identified putative metal ion-binding sites at the subunit interfaces that were consistent with the observed activation of the enzyme by Zn2+ions. The structures reported here reveal the details of the catalytic mechanism of SAS enzymes and provide a molecular basis for understanding differential regulation of SAS enzymes in Firmicute bacteria.

U2 - 10.1074/jbc.RA117.001374

DO - 10.1074/jbc.RA117.001374

M3 - Journal article

C2 - 29326162

VL - 293

SP - 3254

EP - 3264

JO - Journal of Biological Chemistry

JF - Journal of Biological Chemistry

SN - 0021-9258

IS - 9

ER -