TABLE 2.

Effects of linker insertions in FliM on its function and binding to other flagellar proteins

Linker position (codon no.)	Introduced sequence	Swarminga rate (mm/h)	Swimminga speed (relative)	Flagellationa (no./cell)	Binding tob:
					FliN	FliG	CheY	CheY-P
16	PPSRG	5.3	0.95	3.1	ND	ND	+	++
38	PRGY	0.4	0.8	3.0	+	+	+	+
60	R60→PPRGG	0.0	0.0	0.0	+	+	+	++
81	P	0.8	0.7	2.9	+	+	+	++
111	PPSRG	4.3	0.9	3.1	ND	ND	ND	ND
132	P	0.0	0.0	0.0	+	±	+	++
144	LPGA	0.4	0.55	2.6	+	+	+	+
163	P	0.0	(0.0)c	1.0	+	+	ND	ND
212	PPSRG	0.4	0.7	2.9	+	+	+	++
227	P	1.0	0.5	3.2	+	+	+	++
241	R240N241→PPRGGD	6.0	0.9	3.0	ND	ND	ND	ND
258	APGS	0.6	(0.0)	3.0	+	+	ND	ND
267	APGS	Trailsd	(0.0)	(0.0)	−	+	ND	ND
282	VPGH	Trails	(0.0)	(0.0)	−	+	ND	ND
310	PPSRG	4.0	0.65	2.8	ND	ND	ND	ND
Wild type	None	7.0	1.0	3.1	+	+	+	+

^a The pMn plasmids carrying the mutant fliM genes expressed from the tac promoter were transformed into the fliM null strain DFB190, and swarming rates, motility in liquid culture, and numbers of flagella were assayed as described in Materials and Methods. In two cases (positions 60 and 241), the linkers replaced some residues, as indicated. Three different wild-type controls were used (the wild-type strain RP437, DFB190[pDFB72] induced with 25 μM IPTG, and DFB190[pHT32] induced with 60 μM IPTG). All gave similar results, and average values are reported. Swimming speeds are expressed relative to wild-type controls and are average values for 48 cells. 

^b Binding experiments were carried out as described in Materials and Methods. The symbols ++, +, and ± indicate three different levels of binding that differed in the amount of coprecipitated FliM by factors of about 2; − indicates no significant binding. ND, not determined. 

^c Parentheses indicate that most cells were nonmotile or nonflagellate but that a small number (one among hundreds) of cells were motile or had a single flagellum. 

^d Trails, satellite microcolonies were observed on swarm plates.