Biology Reference
In-Depth Information
FIGURE 17.1
A structure-based alignment of bacterial BtubA and BtubB and eukaryotic
-tubulin.
The secondary structures of bacterial tubulin (PDB entry 2btq) and pig brain tubulin (PDB
1jff) were aligned with PDBeFold (
http://www.ebi.ac.uk/msd-srv/ssm/
;
Krissinel & Henrick,
2004
). The secondary structure element names of tubulin are as described before (
L ยจ we,
Downing, and Nogales, 2001
) and the
- and
a
b
-tubulin residues in contact with the anticancer drug
taxol are in gray boxes. The amino acid residues which are missing from each crystal
structure were added (dash box marked in blue) solely to show the complete protein
sequences, whose loops should be separately aligned. The C-terminal domains are boxed.
b
The BtubA/B structure showed a heterodimer and both proteins copolymerize in
the presence of GTP and magnesium into tubulin-like protofilaments (
Martin-
Galiano et al., 2011; Schlieper et al., 2005; Sontag, Sage, & Erickson, 2009;
Sontag, Staley, & Erickson, 2005
). But in the BtubA/B heterodimer crystal structure,
it is not possible to assign BtubA or BtubB to
-or
-tubulin, because it contains a
a
b
continuous
filament, and both BtubA and BtubB have an activating
T7 loop sequence and a short S9-S10 loop in the taxol binding pocket (
Schlieper
ABABAB
...
...
