Reaction mechanism evolutionary analysis and role of zinc in Drosophila methionine R sulfoxide reductase
Yükleniyor...
Dosyalar
Tarih
2002
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
J Biol Chem
Erişim Hakkı
info:eu-repo/semantics/openAccess
Özet
Methionine residues in proteins are susceptible to oxidation,
and the resulting methionine sulfoxides can be
reduced back to methionines by methionine-S-sulfoxide
reductase (MsrA) and methionine-R-sulfoxide reductase
(MsrB). Herein, we have identified two MsrB families
that differ by the presence of zinc. Evolutionary analyses
suggested that the zinc-containing MsrB proteins
are prototype enzymes and that the metal was lost in
certain MsrB proteins later in evolution. Zinc-containing
Drosophila MsrB was further characterized. The enzyme
was found to employ a catalytic Cys124 thiolate,
which directly interacted with methionine sulfoxide, resulting
in methionine and a Cys124 sulfenic acid intermediate.
A subsequent reaction of this intermediate
with Cys69 generated an intramolecular disulfide. Dithiothreitol
could reduce either the sulfenic acid or the
disulfide, but the disulfide was a preferred substrate for
thioredoxin, a natural electron donor. Interestingly, the
C69S mutant could complement MsrA/MsrB deficiency
in yeast, and the corresponding natural form of mouse
MsrB was active with thioredoxin. These data indicate
that MsrB proteins employ alternative mechanisms for
sulfenic acid reduction. Four other conserved cysteines
in Drosophila MsrB (Cys51, Cys54, Cys101, and Cys104)
were found to coordinate structural zinc. Mutation of
any one or a combination of these residues resulted in
complete loss of metal and catalytic activity, demonstrating
an essential role of zinc in Drosophila MsrB. In
contrast, two conserved histidines were important for
thioredoxin-dependent activity, but were not involved
in zinc binding. A Drosophila MsrA gene was also
cloned, and the recombinant enzyme was found to be
metal-free and specific for methionine S-sulfoxide and
to employ a similar sulfenic acid/disulfide mechanism.
Açıklama
J Biol Chem
Anahtar Kelimeler
Kaynak
J Biol Chem
WoS Q Değeri
Scopus Q Değeri
Cilt
277
Sayı
40
Künye
Abhilash, K., KOÇ, A., Ronald, C., & Vadim, G. (2002). Reaction mechanism evolutionary analysis and role of zinc in Drosophila methionine R sulfoxide reductase . J Biol Chem, (277 (40)), 37527–0.
