 |
PDBsum entry 5t6b
|
|
|
|
References listed in PDB file
|
 |
|
Key reference
|
|
|
Title
|
|
Structural studies on kijd1, A sugar c-3'-Methyltransferase.
|
|
|
Authors
|
|
G.T.Dow,
J.B.Thoden,
H.M.Holden.
|
|
|
Ref.
|
|
Protein Sci, 2016,
25,
2282-2289.
|
|
|
PubMed id
|
|
|
|
|
|
Abstract
|
|
|
Kijanimicin is an antitumor antibiotic isolated from Actinomadura kijaniata. It
is composed of three distinct moieties: a pentacyclic core, a monosaccharide
referred to as d-kijanose, and a tetrasaccharide chain composed of l-digitoxose
units. d-Kijanose is a highly unusual nitro-containing tetradeoxysugar, which
requires at least ten enzymes for its production. Here we describe a structural
analysis of one of these enzymes, namely KijD1, which functions as a
C-3'-methyltransferase using S-adenosylmethionine as its cofactor. For this
investigation, two ternary complexes of KijD1, determined in the presence of
S-adenosylhomocysteine (SAH) and dTDP or SAH and
dTDP-3-amino-2,3,6-trideoxy-4-keto-3-methyl-d-glucose, were solved to 1.7 or
1.6 Å resolution, respectively. Unexpectedly, these structures, as well as
additional biochemical analyses, demonstrated that the quaternary structure of
KijD1 is a dimer. Indeed, this is in sharp contrast to that previously observed
for the sugar C-3'-methyltransferase isolated from Micromonospora chalcea. By
the judicious use of site-directed mutagenesis, it was possible to convert the
dimeric form of KijD1 into a monomeric version. The quaternary structure of
KijD1 could not have been deduced based solely on bioinformatics approaches, and
thus this investigation highlights the continuing need for experimental
validation.
|
|
|
|
|
|
|
