PDBsum entry 7oa2

Hydrolase

PDB id: 7oa2

Contents

Protein chain

177 a.a.

Ligands

POP

Metals

__K

Waters ×30

PDB id:

7oa2

Name:

Hydrolase

Title:

Triphosphate tunnel metalloenzyme from sulfolobus acidocaldarius in complex with pyrophosphate

Structure:

Triphosphate tunnel metalloenzyme saci_0718. Chain: a. Synonym: conserved archaeal protein,adenylate cyclase. Engineered: yes

Source:

Sulfolobus acidocaldarius (strain atcc 33909 / dsm 639 / jcm 8929 / nbrc 15157 / ncimb 11770). Organism_taxid: 330779. Strain: atcc 33909 / dsm 639 / jcm 8929 / nbrc 15157 / ncimb 11770. Gene: saci_0718. Expressed in: escherichia coli bl21(de3). Expression_system_taxid: 469008.

Resolution:

2.70Å R-factor: 0.291 R-free: 0.318

Authors:

M.S.Vogt,L.-O.Essen,A.Banerjee

Key ref:

M.S.Vogt et al. (2021). The archaeal triphosphate tunnel metalloenzyme SaTTM defines structural determinants for the diverse activities in the CYTH protein family. J Biol Chem, 297, 100820. PubMed id: 34029589 DOI: 10.1016/j.jbc.2021.100820

Date:

19-Apr-21 Release date: 02-Jun-21

Protein chain

Q4JAT2  (Q4JAT2_SULAC) -  Conserved Archaeal protein from Sulfolobus acidocaldarius (strain ATCC 33909 / DSM 639 / JCM 8929 / NBRC 15157 / NCIMB 11770)

Seq: 185 a.a.

Struc: 177 a.a.

Enzyme reactions

• Enzyme class: E.C.?

DOI no: 10.1016/j.jbc.2021.100820

J Biol Chem 297:100820 (2021)

PubMed id: 34029589

The archaeal triphosphate tunnel metalloenzyme SaTTM defines structural determinants for the diverse activities in the CYTH protein family.

M.S.Vogt, R.R.Ngouoko Nguepbeu, M.K.F.Mohr, S.V.Albers, L.O.Essen, A.Banerjee.

ABSTRACT

CYTH proteins make up a large superfamily that is conserved in all three domains of life. These enzymes have a triphosphate tunnel metalloenzyme (TTM) fold, which typically results in phosphatase functions, e.g., RNA triphosphatase, inorganic polyphosphatase, or thiamine triphosphatase. Some CYTH orthologs cyclize nucleotide triphosphates to 3',5'-cyclic nucleotides. So far, archaeal CYTH proteins have been annotated as adenylyl cyclases, although experimental evidence to support these annotations is lacking. To address this gap, we characterized a CYTH ortholog, SaTTM, from the crenarchaeote Sulfolobus acidocaldarius. Our in silico studies derived ten major subclasses within the CYTH family implying a close relationship between these archaeal CYTH enzymes and class IV adenylyl cyclases. However, initial biochemical characterization reveals inability of SaTTM to produce any cyclic nucleotides. Instead, our structural and functional analyses show a classical TTM behavior, i.e., triphosphatase activity, where pyrophosphate causes product inhibition. The Ca²⁺-inhibited Michaelis complex indicates a two-metal-ion reaction mechanism analogous to other TTMs. Cocrystal structures of SaTTM further reveal conformational dynamics in SaTTM that suggest feedback inhibition in TTMs due to tunnel closure in the product state. These structural insights combined with further sequence similarity network-based in silico analyses provide a firm molecular basis for distinguishing CYTH orthologs with phosphatase activities from class IV adenylyl cyclases.