TABLE 2.

Phenotypes of E. coli cells expressing dnaK mutations in a ΔdnaK52 background^a

DnaK	λ sensitivityb	Growth at 42°Cc	Cell morphologyd
Wild type	106	+++	Unfilamented
T199S	108	+	Filamented
T199A	None	None	Filamented
K70A	None	None	Filamented

^aThe ΔdnaK52 allele was transduced into strains GW8305, GW8309, TB1009, and TB1031. 

^bλ sensitivity assays were performed as described in the text, and λ sensitivity is expressed as the number of PFU of λcI⁻ phage required to show any visible clearing of cells when spotted in a 2-μl drop on a growing lawn of cells. 

^cLB broth (5 ml) containing 0.5 mM IPTG, ampicillin, chloramphenicol, and kanamycin was inoculated with single-colony picks from the transductions and incubated at 42°C. Following a 16-h incubation, the extent of growth in each culture was scored from no growth (0) to confluent (+++). 

^dFor cell morphology observations, strains expressing wild-type or mutant DnaK in a ΔdnaK background were grown at 30°C on LB plates containing 0.5 mM IPTG, ampicillin, chloramphenicol, and kanamycin. Multiple colonies were picked for each strain and observed microscopically. Microscopic analyses were done on a Zeiss Axioplan Universal microscope with Nomarski optics.