A1 Refereed original research article in a scientific journal
The tetrameric structure of nucleotide-regulated pyrophosphatase and its modulation by deletion mutagenesis and ligand binding
Authors: Anashkin VA, Salminen A, Orlov VN, Lahti R, Baykov AA
Publisher: ELSEVIER SCIENCE INC
Publication year: 2020
Journal:Archives of Biochemistry and Biophysics
Journal name in sourceARCHIVES OF BIOCHEMISTRY AND BIOPHYSICS
Journal acronym: ARCH BIOCHEM BIOPHYS
Article number: ARTN 108537
Volume: 692
Number of pages: 10
ISSN: 0003-9861
eISSN: 1096-0384
DOI: https://doi.org/10.1016/j.abb.2020.108537
Abstract
A quarter of prokaryotic Family II inorganic pyrophosphatases (PPases) contain a regulatory insert comprised of two cystathionine beta-synthase (CBS) domains and one DRTGG domain in addition to the two catalytic domains that form canonical Family II PPases. The CBS domain-containing PPases (CBS-PPases) are allosterically activated or inhibited by adenine nucleotides that cooperatively bind to the CBS domains. Here we use chemical cross-linking and analytical ultracentrifugation to show that CBS-PPases from Desulfitobacterium hafniense and four other bacterial species are active as 200-250-kDa homotetramers, which seems unprecedented among the four PPase families. The tetrameric structure is stabilized by Co2+, the essential cofactor, pyrophosphate, the substrate, and adenine nucleotides, including diadenosine tetraphosphate. The deletion variants of dhPPase containing only catalytic or regulatory domains are dimeric. Co2+ depletion by incubation with EDTA converts CBS-PPase into inactive tetrameric and dimeric forms. Dissociation of tetrameric CBS-PPase and its catalytic part by dilution renders them inactive. The structure of CBS-PPase tetramer was modelled from the structures of dimeric catalytic and regulatory parts. These findings signify the role of the unique oligomeric structure of CBS-PPase in its multifaced regulation.
A quarter of prokaryotic Family II inorganic pyrophosphatases (PPases) contain a regulatory insert comprised of two cystathionine beta-synthase (CBS) domains and one DRTGG domain in addition to the two catalytic domains that form canonical Family II PPases. The CBS domain-containing PPases (CBS-PPases) are allosterically activated or inhibited by adenine nucleotides that cooperatively bind to the CBS domains. Here we use chemical cross-linking and analytical ultracentrifugation to show that CBS-PPases from Desulfitobacterium hafniense and four other bacterial species are active as 200-250-kDa homotetramers, which seems unprecedented among the four PPase families. The tetrameric structure is stabilized by Co2+, the essential cofactor, pyrophosphate, the substrate, and adenine nucleotides, including diadenosine tetraphosphate. The deletion variants of dhPPase containing only catalytic or regulatory domains are dimeric. Co2+ depletion by incubation with EDTA converts CBS-PPase into inactive tetrameric and dimeric forms. Dissociation of tetrameric CBS-PPase and its catalytic part by dilution renders them inactive. The structure of CBS-PPase tetramer was modelled from the structures of dimeric catalytic and regulatory parts. These findings signify the role of the unique oligomeric structure of CBS-PPase in its multifaced regulation.
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