The plasmid YEplac195-PXKS1 was constructed as follows: (1)
Primers PGK1XK1-U and PGK1XK1-D were used to amplify the
promoter of PGK1. This PCR product was digested by HindIII-SphI
and ligated with YEplac195 to form YEplac195-PGK1XK1 plasmid;
(2) PGK1 terminator was amplified by PCR with primers
PGK1XK1T-U and PGK1XK1T-D, which was digested by SalI-EcoRI
and then inserted into the same sites of YEplac195-PGK1XK1 to
create YEplac195-PGK1XK1-PGK1XK1T; (3) Primers XKS1-U and
XKS1-D was used to PCR amplify the ORF of XKS1, and this PCR
product was digested by SphI-SalI and then ligated with
YEplac195-PGK1XK1-PGK1XK1T to build plasmid YEplac195-
PXKS1.