Table 1.

Complementation of capsule synthesis by mutant Lon

Host	Plasmid	Arabinose concentration in medium,
		0%	0.001%	0.01%	0.1%
		Expression of a cpsB∷lacZ fusion (specific activity)
Δlon	pBAD24 (vector)	46	18	12	11
	pBADlon+	40	5	N.D.	N.D.
	pBADlonS679A	36	8	3	4
	pBADlonK362Q	42	17	14	10
	pBADlonK362Q-S679A	45	15	12.5	20
lon+	pBAD24	0.9	N.D.	N.D.	0.4

N.D., not done. Cells carrying the pBADlon⁺ plasmid ceased growth or lost the plasmid at the higher arabinose concentrations. Δlon strain is SG22569; the lon⁺ host is SG22542. Lower β-galactosidase levels for strains carrying the pBAD24 vector at high arabinose concentrations were reproducibly observed; the basis for this is not known.