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Figure 2.
Figure 2: Regulation of protease activity by oligomer
reassembly. a, Ribbon plot of the protease domain of DegP[6]
(1kj9) and DegP[24], highlighting the mechanistically important
loops LA*, LD, L1, L2 and L3. Residues of the catalytic triad
(Asp 105, His 135 and Ala 210) are shown in stick mode and the
loop nomenclature used^12, ^41 is indicated. b, Electron density
of the active-site loops L1 and LD. The 2F[o] - F[c] simulated
annealing omit map was calculated at 3.0 Å resolution
(contoured at 1.1  )
after omitting loops L1 and LD from the refined model. The
oxyanion hole (blue sphere) and the main-chain carbonyl group of
Arg 207 are highlighted. The position of the latter oxygen is a
distinctive feature of proteolytically active HtrA proteases. c,
Denatured lysozyme and DegP[6] were incubated in different
ratios and the resulting complexes were analysed by SEC. Left:
incubation of different amounts of lysozyme (orange, 30  M;
red, 300 M;
blue, 600 M)
with DegP[6] (15 M).
Right: incubation of different amounts of DegP[6] (orange, 3
M;
red, 15 M;
blue, 65 M)
with lysozyme (170 M).
d, Brief incubation of wild-type DegP with casein (1 min,
magenta line) resulted in the formation of the DegP[24]–casein
complex (the pronounced low-molecular-mass peak represents
unprocessed casein). After completion of degradation (30 min,
green line), DegP recycled into its hexameric state. Composites
of individual elution peaks are indicated on the SDS gel; the
self-cleavage products of DegP are labelled DegP*.
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