Table 1.

Oligonucleotides used in this study

Designation	Sequence
ychBvo	5′-GAGGAGAAATTAACCATGCGGACACAGTGGCCC-3′
ychBhi	5′-GTCACCGAACTGCAGCTTGCCCG-3′
kEcoRI	5′-ACACAGAATTCATTAAAGAGGAGAAATTAACCATG-3′