The Escherichia coli NarL receiver domain regulates transcription through promoter specific functions

BMC Microbiology

Table 1 Summary of sedimentation equilibrium results^a,b

Construct	Sequence MM^c (kDa)^c	Speed (krpm)^c	Measured MM at 60 μM (kDa)	Measured MM at 160 μM (kDa)	Predominant Oligomeric State
NarL^{C (147–216)}	9.6	15	9.7	12.3	Monomer
		22	9.6	11.4
NarL^{C (126–216)}	11.8	15	14.1	13.6	Monomer
		22	12.7	12.4
NarL	23.9	11	24.0	23.9	Monomer
		15	22.6	23.0
NarL^N	16.5	15	26.1	25.9	Monomer/Dimer
		22	23.4	23.0
NarL^N-P	16.6	15	30.8	30.4	Dimer
		22	29.0	27.4

^aCertain constructs had additional data collected at other speeds that are not shown in the table but were included in determining the best oligomeric fit (discussed in text)
^bAll runs shown were carried out in a buffer solution containing 25 mM Tris, pH 7.5-8.5 and 500 mM NaCl, except for two cases: NarL^{C (147–214)} at 60 μM contained 500 mM (NH₄)₂SO₄, and NarL at 60 μM contained 100 mM NaCl. These changes to salt did not significantly alter the measured molecular masses (see Materials and Methods)
^cMM: molecular mass; kDa: kiloDalton; krpm: kilorevolutions per minute

ISSN: 1471-2180