The Analysis of Impurities in Various Stages of Recycled Carbon Tetrachloride and Correlation With Chlorination Properties

Hudson, R. L.; Burkhart, L.E.; Larson, Chris

doi:10.2172/4346952

Cited by 1 publication

(10 citation statements)

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“…Here, we further characterize freyrasin, a ranthipeptide from Paenibacillus polymyxa ATCC 842. 7 Like the previously reported thermocellin and Tte1186a, 18,27 the freyrasin rSAM maturase, PapB (WP_019688962.1), has considerably higher sequence similarity to QhpD than does NxxcB (BLAST query coverage of 94% with 50% sequence similarity, bit score 229). The freyrasin precursor (PapA) contains six Cys-X 3 -Asp motifs where X is any amino acid residue.…”

Section: Introductionsupporting

confidence: 49%

“…1,6 The ranthipeptides (radical non-α-carbon thioether peptides) are a recently reported class of RiPP characterized by the presence of a Cys-rich precursor peptide and a locally encoded radical S-adenosylmethionine (rSAM)-dependent enzyme (PF04055, Figure 1). 7 Although they bear a superficial resemblance to the sactipeptides, which contain sulfur-to-α-carbon thioether linkages, the ranthipeptide-forming rSAM enzymes install a thioether modification at a non-α carbon (i.e. the side chain) of an acceptor residue.…”

Section: Introductionmentioning

confidence: 99%

“…the side chain) of an acceptor residue. 7,8 Given their rSAMdependent formation, ranthipeptides are distinguished from the structurally similar lanthipeptides, which contain β-thioether linkages to dehydrated Ser/Thr residues via a Michael-like nucleophilic addition. 9 rSAM enzymes, constituting one of the largest enzyme superfamilies, 10 are present in a large number of RiPP biosynthetic pathways and carry out multiple difficult chemical transformations.…”

Section: Introductionmentioning

confidence: 99%

“…Sequence analysis of the rSAM enzymes revealed that many ranthipeptide synthases bear high sequence similarity to quinohemoprotein amine dehydrogenase maturase (QhpD). 7 The QhpD-like subset of ranthipeptides was previously reported in a computational study 20 and the peptides were initially termed SCIFFs (six Cys in forty-five residues) based on a conserved precursor peptide sequence. QhpD is an rSAM enzyme necessary for the maturation of quinohemoprotein amine dehydrogenase (QHNDH), a protein complex found in some Gram-negative bacteria (Figure S2).…”

Section: Introductionmentioning

confidence: 99%

“…[22][23][24] Indeed, the high level of sequence similarity between the "SCIFF" rSAM enzymes and QhpD was an early indicator that SCIFFs might not be sactipeptides, but instead belonged to a new class of RiPP and have been recategorized as members of the ranthipeptide class. 7 Thus far, there has been a single report of a non-SCIFF ranthipeptide whose maturase, NxxcB, catalyzes thioether formation between the Cys thiol and the βcarbon of an Asn three residues upstream. 26 BLAST-based sequence comparison between QhpD from Paracoccus denitrificans (SDJ52620.1) and NxxcB (WP_018375754.1) yields a query coverage of 42% with 45% sequence similarity over the aligned region (bit score 52).…”

Section: Introductionmentioning

confidence: 99%

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Reconstitution and Substrate Specificity of the Thioether-Forming Radical S-Adenosylmethionine Enzyme in Freyrasin Biosynthesis

2019

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The radical non-α-carbon thioether peptides (ranthipeptides) are a newly described class of ribosomally synthesized and post-translationally modified peptide (RiPP). Ranthipeptide biosynthetic gene clusters are characterized by a Cys-rich precursor peptide and a radical Sadenosylmethionine (rSAM)-dependent enzyme that forms a thioether linkage between a Cys donor and an acceptor residue. Unlike the sulfur-to-α-carbon linked thioether peptides (sactipeptides), known ranthipeptides contain thioethers to either the βor γ-carbon (i.e. non-αcarbon) of an acceptor residue. Recently, we reported the discovery of freyrasin, a ranthipeptide from Paenibacillus polymyxa, which contains six thioethers from Cys-X 3 -Asp motifs present in the precursor peptide (PapA). The linkages are exclusively to the β-carbon of Asp (S-Cβ). In this report, we performed mutational analysis of PapA and the cognate thioether-forming rSAM enzyme (PapB) to define the substrate scope. Using a mass spectrometry-based activity assay, our data show that PapB is intolerant towards Ala and Asn in the acceptor position but will tolerate Glu-containing variants. NMR spectroscopic data of a Glu variant demonstrated that the thioether linkage was to the 4-position of Glu (S-Cγ). Furthermore, we demonstrate that PapB is intolerant to expansion and contraction of the thioether motifs (Cys-X n -Asp, n=2,4), although a minimal substrate featuring only one Cys-X 3 -Asp motif was competent for thioether formation. Akin to the sactipeptides, PapB was dependent on a RiPP recognition element (RRE) to bind the cognate precursor peptide, with deletion resulting in loss-of-function in vivo. The activity of PapB could be restored in vivo by supplying the excised RRE in trans. Finally, we reconstituted the activity of PapB in vitro, which lead to modification of all six Cys residues in PapA. These studies provide insights into ranthipeptide biosynthesis and expand our understanding of rSAM enzyme chemistry in natural product biosynthesis.

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Section: Introductionsupporting

confidence: 49%

Section: Introductionmentioning

confidence: 99%