Structural and Kinetic Insight into the Biosynthesis of H2S and l-Lanthionine from l-Cysteine by a Pyridoxal l-Phosphate-Dependent Enzyme from Fusobacterium nucleatum

Fusobacterium nucleatum is a common oral bacterium and a major producer of H2S, a toxic gas linked to the pathogenesis of periodontal disease. The bacterium encodes a fold type II pyridoxal l-phosphate (PLP)-dependent enzyme, Fn1220 or lanthionine synthase (LS), that generates H2S and l-lanthionine (a component of the peptidoglycan layer) through β-replacement of l-cysteine by a second molecule of l-cysteine. Herein, we show through detailed kinetic analysis that LS elicits catalytic promiscuity as demonstrated for other fold type II PLP-dependent homologues, namely, O-acetylserine sulfhydrylase (OASS) and cystathionine β-synthase (CBS). Like OASS, LS can assimilate H2S by catalyzing the β-replacement of O-acetyl-l-serine by sulfide to form l-cysteine. However, the turnover for this reaction in LS is slower than that of other studied OASS enzymes due to slower conversion to the α-aminoacrylate intermediate. Similar to yeast and human CBS, LS can generate H2S and l-cystathionine through β-replacement of l-cysteine by a second molecule of l-homocysteine; however, whereas this is the main H2S-forming reaction in CBS, it is not for LS. LS shows a marked preference for forming H2S and l-lanthionine through the condensation of 2 equiv of l-cysteine. Sequence alignment of LS with other CBS and OASS enzymes and inspection of the LS crystal structure in the external aldimine state with l-lanthionine reveal that LS possesses a unique loop that engages in hydrogen-bond contact with the product, providing a structural rationale for the enzyme's catalytic preference for H2S and l-lanthionine biosynthesis.

Medienart:

E-Artikel

Erscheinungsjahr:

2019

Erschienen:

2019

Enthalten in:

Zur Gesamtaufnahme - volume:58

Enthalten in:

Biochemistry - 58(2019), 34 vom: 27. Aug., Seite 3592-3603

Sprache:

Englisch

Beteiligte Personen:

Mothersole, Robert G [VerfasserIn]
Wolthers, Kirsten R [VerfasserIn]

Links:

Volltext

Themen:

5V5IOJ8338
Alanine
Bacterial Proteins
Comparative Study
Cystathionine beta-Synthase
Cysteine
Cysteine Synthase
EC 2.5.1.47
EC 4.2.1.-
EC 4.2.1.22
Hydro-Lyases
Hydrogen Sulfide
JO78O46X3K
Journal Article
K848JZ4886
Lanthionine
Lanthionine synthase
Multienzyme Complexes
OF5P57N2ZX
Pyridoxal Phosphate
Research Support, Non-U.S. Gov't
Sulfides
YY9FVM7NSN

Anmerkungen:

Date Completed 25.06.2020

Date Revised 25.06.2020

published: Print-Electronic

Citation Status MEDLINE

doi:

10.1021/acs.biochem.9b00487

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM300086121