Abstract Type II fatty acid synthesis (FAS II) is an essential
process for bacteria survival, and malonyl-CoA:acyl carrier protein
transacylase (MCAT) is a key enzyme in FAS II pathway,
which is responsible for transferring the malonyl group from
malonyl-CoA to the holo-ACP by forming malonyl-ACP. In this
work, we described the cloning, characterization and enzymatic
inhibition of a new MCAT from Helicobacter pylori strain SS1
(HpMCAT), and the gene sequence of HpfabD was deposited in
the GenBank database (Accession No. AY738332). Enzymatic
characterization of HpMCAT showed that the Km value for
malonyl-CoA was 21.01 2.3 lM, and the thermal- and guanidinium
hydrochloride-induced unfolding processes for HpMCAT
were quantitatively investigated by circular dichroism spectral
analyses. Moreover, a natural product, corytuberine, was discovered
to demonstrate inhibitory activity against HpMCAT with
IC50 value at 33.1 3.29 lM. Further enzymatic assay results
indicated that corytuberine inhibits HpMCAT in an uncompetitive
manner. To our knowledge, this is the firstly reported
MCAT inhibitor to date. This current work is hoped to supply
useful information for better understanding the MCAT features
of H. pylori strain, and corytuberine might be used as a potential
lead compound in the discovery of the antibacterial agents using
HpMCAT as target.