Structural and spectroscopic analyses of the sporulation killing factor biosynthetic enzyme SkfB, a bacterial AdoMet radical sactisynthase

Tsehai A.J. Grell, William M. Kincannon, Nathan A. Bruender, Elizabeth J. Blaesi, Carsten Krebs, Vahe Bandarian, Catherine L. Drennan

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Sactipeptides are a subclass of ribosomally synthesized and post-translationally modified peptides (RiPPs). They contain a unique thioether bond, referred to as a sactionine linkage, between the sulfur atom of a cysteine residue and the α-carbon of an acceptor residue. These linkages are formed via radical chemistry and are essential for the spermicidal, antifungal, and antibacterial properties of sactipeptides. Enzymes that form these linkages, called sactisynthases, are AdoMet radical enzymes in the SPASM/Twitch subgroup whose structures are incompletely characterized. Here, we present the X-ray crystal structure to 1.29-Å resolution and Mössbauer analysis of SkfB, a sactisynthase from Bacillus subtilis involved in making sporulation killing factor (SKF). We found that SkfB is a modular enzyme with an N-terminal peptide-binding domain comprising a RiPP recognition element (RRE), a middle domain that forms a classic AdoMet radical partial (β/α)6 barrel structure and displays AdoMet bound to the [4Fe-4S] cluster, and a C-terminal region characteristic of the so-called Twitch domain housing an auxiliary iron-sulfur cluster. Notably, both crystallography and Mössbauer analyses suggest that SkfB can bind a [2Fe-2S] cluster at the auxiliary cluster site, which has been observed only once before in a SPASM/Twitch auxiliary cluster site in the structure of another AdoMet radical enzyme, the pyrroloquinoline quinone biosynthesis enzyme PqqE. Taken together, our findings indicate that SkfB from B. subtilis represents a unique enzyme containing several structural features observed in other AdoMet radical enzymes.

Original languageEnglish (US)
Pages (from-to)17349-17361
Number of pages13
JournalThe Journal of biological chemistry
Volume293
Issue number45
DOIs
StatePublished - Nov 9 2018
Externally publishedYes

Fingerprint

S-Adenosylmethionine
Enzymes
Bacillus subtilis
Sulfur
PQQ Cofactor
Peptides
Crystallography
Biosynthesis
Sulfides
Bacilli
Cysteine
Carbon
Iron
Crystal structure
X-Rays
X rays
Atoms

Keywords

  • AdoMet radical enzymes
  • catalysis
  • crystal structure
  • enzyme catalysis
  • enzyme structure
  • iron sulfur clusters
  • metalloenzyme
  • radical SAM
  • sactionine linkage
  • sporulation killing factor

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Cite this

Structural and spectroscopic analyses of the sporulation killing factor biosynthetic enzyme SkfB, a bacterial AdoMet radical sactisynthase. / Grell, Tsehai A.J.; Kincannon, William M.; Bruender, Nathan A.; Blaesi, Elizabeth J.; Krebs, Carsten; Bandarian, Vahe; Drennan, Catherine L.

In: The Journal of biological chemistry, Vol. 293, No. 45, 09.11.2018, p. 17349-17361.

Research output: Contribution to journalArticle

Grell, Tsehai A.J. ; Kincannon, William M. ; Bruender, Nathan A. ; Blaesi, Elizabeth J. ; Krebs, Carsten ; Bandarian, Vahe ; Drennan, Catherine L. / Structural and spectroscopic analyses of the sporulation killing factor biosynthetic enzyme SkfB, a bacterial AdoMet radical sactisynthase. In: The Journal of biological chemistry. 2018 ; Vol. 293, No. 45. pp. 17349-17361.
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AU - Grell, Tsehai A.J.

AU - Kincannon, William M.

AU - Bruender, Nathan A.

AU - Blaesi, Elizabeth J.

AU - Krebs, Carsten

AU - Bandarian, Vahe

AU - Drennan, Catherine L.

PY - 2018/11/9

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AB - Sactipeptides are a subclass of ribosomally synthesized and post-translationally modified peptides (RiPPs). They contain a unique thioether bond, referred to as a sactionine linkage, between the sulfur atom of a cysteine residue and the α-carbon of an acceptor residue. These linkages are formed via radical chemistry and are essential for the spermicidal, antifungal, and antibacterial properties of sactipeptides. Enzymes that form these linkages, called sactisynthases, are AdoMet radical enzymes in the SPASM/Twitch subgroup whose structures are incompletely characterized. Here, we present the X-ray crystal structure to 1.29-Å resolution and Mössbauer analysis of SkfB, a sactisynthase from Bacillus subtilis involved in making sporulation killing factor (SKF). We found that SkfB is a modular enzyme with an N-terminal peptide-binding domain comprising a RiPP recognition element (RRE), a middle domain that forms a classic AdoMet radical partial (β/α)6 barrel structure and displays AdoMet bound to the [4Fe-4S] cluster, and a C-terminal region characteristic of the so-called Twitch domain housing an auxiliary iron-sulfur cluster. Notably, both crystallography and Mössbauer analyses suggest that SkfB can bind a [2Fe-2S] cluster at the auxiliary cluster site, which has been observed only once before in a SPASM/Twitch auxiliary cluster site in the structure of another AdoMet radical enzyme, the pyrroloquinoline quinone biosynthesis enzyme PqqE. Taken together, our findings indicate that SkfB from B. subtilis represents a unique enzyme containing several structural features observed in other AdoMet radical enzymes.

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KW - sporulation killing factor

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