Table II. Complementation of strain PAL421Tr at non-permissive temperature with various constructs.

Plasmid used	PDF overproductiona	PDF in soluble fractionb	Complementation of strain PAL421Trc
pQE60	–	–	–
pUCdef	+++	++	+
pQdef1a	+++	ND	–
pQdef1aΔN	+++	+++	+
pQdef1b	+	ND	+
pQdef1bΔN	++	++	+

^aProduction of the overproduced protein in JM101Tr, as assessed by PAGE and protein concentration measurement, was approximately 0 (–), 0.2 ± 0.1 (+), 1.0 ± 0.5 (++) or 4.0 ± 2.0 (+++) mg of PDF obtained from 20 ml of harvested bacteria.

^bWhen PDF could not be shown by Coomassie staining (PDF1B) or western blot analysis (PDF1A) using anti-His-tag antibodies, ND (not detectable) is indicated.

^cPAL421Tr strain was transformed at 30°C by the indicated plasmid. Ampicillin-resistant cells were then re-streaked at 42°C on pre-heated LB plates containing 100 µg/ml ampicillin and 0.5 mM IPTG (2 g/l glucose in the case of pUCdef).

+, a plasmid allowing normal cell growth after 12–24 h.

–, no growth after 24 h.