TABLE 4.

Effect of leader deletions on cysH expression

Strain	β-Galactosidase activitya (MU)
	− Sulfur	+ Cystine	+ Metb	Met + cystine
MC-MET530	1,034	174	658	119
MC-MET249	715	290	490	282
MC-MET276Xc	192	229	194	241
MC328	1,135	1,290	—d	—

^aCells were grown in sulfur-free minimal media containing cystine and methionine; the culture was then washed, split, and grown in the presence (+) or absence (−) of sulfur sources. Samples were taken 4 h after cultures were split. 

^bMet, methionine. 

^cIn experiments performed with strain MC-MET276X, 0.2% xylose was added to the growth media. 

^d—, not determined.