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Figure 4.
FIGURE 4. Structures of  N1pro-cd-InpA C154A and
wt cd-InpA. A, Richardson diagram of N1pro-cd-InpA C154A in
standard orientation. The pro-domain is displayed in blue/cyan
and the mature protein moiety (subdivided into a right and a
left subdomain) in yellow/brown. The subdomains, the regular
secondary structure elements (see Fig. 1), the N- and the C
terminus, the primary activation point (at Asn^111-Val^112), and
the structure regions responsible for latency maintenance are
marked and labeled. B, superimposition of the C  -carbon
traces of N1pro-cd-InpA C154A
(yellow) and wt mature cd-InpA (red) in standard orientation.
Some residues of N1pro-cd-InpA C154A are
labeled for reference. C, close-up view of the active site of
N1pro-cd-InpA C154A.
Orientation as in B after a horizontal rotation of  45°.
D, same as in C but for wt active cd-InpA. E, C -trace
of the structure of N1pro-cd-InpA C154A
(yellow) and wt mature cd-InpA (red) around the active site,
including the catalytic cysteine residue (Cys^154; mutated to
alanine in N1pro-cd-InpA C154A),
imbedded in active-site helix 2(circled 1), the
zymogenic hairpin (circled 3) encompassing the catalytic
histidine (His^305) (undefined from Ser^295 to Gln^301 in N1pro-cd-InpA C154A)
(circled 4), the backing helix 1 (absent in cd-InpA)
(circled 1), and the latency-flap, displayed from Tyr^332 to
Met^351 for either structure (circled 2). The gray arrows
indicate the displacements of the keynote structural elements
upon zymogen activation as explained in the text.
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