Biomedical Engineering Reference
In-Depth Information
nucleus.
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It is likely, given the results of Azimzadeh et al., that the tag would
have been removed during the proteolytic maturation to p68. The relevance
and requirement for this proteolytic maturation of PfA-M1, and the precise
function of each of its forms, remain to be elucidated.
7.2.1.2 X-Ray Crystal Structure of PfA-M1
The high-resolution X-ray crystal structure of a recombinant form of PfA-M1
that lacked the 193 aa N-terminal extension of the enzyme including the trans-
membrane region (this closely matches the p96 form of the enzyme) has been
determined and shows that the protease adopts a canonical bacterial amino-
peptidase fold and comprises 26 a-helices and seven b-sheets divided into four
domains (3EBG.pdb; Figure 7.1A).
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The N-terminal b-domain I (residues 194-
391) consists of a central seven-stranded b-sheet (b
12
b
13
b
10
b
1
b
2
b
7
b
4
) enclosed by
two smaller sheets (b
3
b
6
b
5
and b
11
b
14
b
9
b
8
). The four-stranded antiparallel sheet
A
B
C
Figure 7.1
X-ray crystal structure of PfA-M1. (A) Cartoon of unbound PfA-M1
colored by domain: I (blue), II (green), III (yellow), IV (red). Molecular
surface of PfA-M1 (colored by domain as indicated for panel A) showing
small N-terminal (B) and large C-terminal (C) openings to the active site
(active site cavity shown in magenta). (Reproduced with permission from
McGowan et al.
30
).
