%0 Journal Article
%A Li, Qinglian
%A Qin, Xiangjing
%A Liu, Jing
%A Gui, Chun
%A Wang, Bo
%A Li, Jie
%A Ju, Jianhua
%D 2016
%T Deciphering
the Biosynthetic Origin of l-allo-Isoleucine
%U https://acs.figshare.com/articles/journal_contribution/Deciphering_the_Biosynthetic_Origin_of_l_i_allo_i_Isoleucine/2089135
%R 10.1021/jacs.5b11380.s001
%2 https://acs.figshare.com/ndownloader/files/3722350
%K bidirectional reaction
%K desotamide biosynthetic pathway
%K MfnO
%K marformycin biosynthetic pathway
%K arginine residue
%K vivo gene inactivations
%K Biosynthetic Origin
%K acid
%K ZJ
%K importance
%K isomerase synergistically
%K Streptomyce
%K origin
%K characterization
%K enzyme pairs
%K biotool development
%K aminotransferase
%K biosynthesi
%K life forms
%K isomerase genes dsaE
%K PLP
%K biosynthetic pathways
%K SCSIO
%K DsaD
%K marformycin titers
%X The nonproteinogenic amino acid l-allo-isoleucine (l-allo-Ile) is featured in
an assortment of life forms comprised of, but not limited to, bacteria,
fungi, plants and mammalian systems including Homo sapiens. Despite its ubiquity and functional
importance, the specific origins of this unique amino acid have eluded
characterization. In this study, we describe the discovery and characterization
of two enzyme pairs consisting of a pyridoxal 5′-phosphate
(PLP)-linked aminotransferase and an unprecedented isomerase synergistically
responsible for the biosynthesis of l-allo-Ile from l-isoleucine (l-Ile) in natural products.
DsaD/DsaE from the desotamide biosynthetic pathway in Streptomyces scopuliridis SCSIO ZJ46, and
MfnO/MfnH from the marformycin biosynthetic pathway in Streptomyces drozdowiczii SCSIO 10141 drive l-allo-Ile generation in each respective system.
In vivo gene inactivations validated the importance of the DsaD/DsaE
pair and MfnO/MfnH pair in l-allo-Ile unit
biosynthesis. Inactivation of PLP-linked aminotransferases DsaD and
MfnO led to significantly diminished desotamide and marformycin titers,
respectively. Additionally, inactivation of the isomerase genes dsaE and mfnH completely abolished production
of all l-allo-Ile-containing metabolites
in both biosynthetic pathways. Notably, in vitro biochemical assays
revealed that DsaD/DsaE and MfnO/MfnH each catalyze a bidirectional
reaction between l-allo-Ile and l-Ile. Site-directed mutagenesis experiments revealed that the enzymatic
reaction involves a PLP-linked ketimine intermediate and uses an arginine
residue from the C-terminus of each isomerase to
epimerize the amino acid β-position. Consequently, these data
provide important new insight into the origins of l-allo-Ile in natural products with medicinal potential and
illuminate new possibilities for biotool development.
%I ACS Publications