Supplemental Information
Biochemical Characterization and Crystal Structure of a GH10 Xylanase from Termite Gut
Bacteria Reveal a Novel Structural Feature and Significance of Its Bacterial Ig-like Domain
Qian Han, Ning Liu, Howard Robinson, Lin Cao, Changli Qian, Qianfu Wang, Lei Xie, Haizhen Ding,
Qian Wang, Yongping Huang, Jianyong Li and Zhihua Zhou
Figure S1. The absorbance changes at 280 nm of Xyl-ORF19 (full length) and Xyl-ORF19-ΔBig_2
(truncated) after heat treatment. Enzymes were diluted to 37μg/ml in 100 mM sodium phosphate buffer,
pH 6.5. Each protein was then heated at various temperatures for 5 min using a DK-8D electrothermostatic water bath (Shanghai Jinghong laboratory instruments Co., Ltd.). The absorbance at 280 nm
was detected using a One Drop Spectrophotometer (Shanghai Cytoeasy Biotech Co.,Ltd.). The Tm
(Midpoint temperature of the protein melting) value for each enzyme was calculated by fitting the
equation to the recorded data (two replicates) using the standard curve analysis function in SigmaPlot
Enzyme Kinetics Module (SPSS, San Jose, CA).
Figure S1. Organization of CD, Big_2 and the linker of Xyl-ORF19. Each domain was shown in surface
presentation, and colored in grey for Big_2, wheat for CD and blue for the linker. Contact residues were
shown in Table S1.
Table S1. Interfacing residues between the Big_2 domain (Big_2) and the Catalytic Domain
(CD) of Xyl-ORF19
Big_2
Residues
TIGQQ
LKF
GANLFL
A
A
Sequence No.
28-32
69-71
75-80
82
84
DDMTIATNR
IL
L
D
AKP
TS
393-401
403-404
443
448
453-455
458-459
CD
Table S2. Hydrogen bonds formed between the Big_2 domain (Big_2) and the Catalytic Domain
(CD) of Xyl-ORF19
Bond No.
1
2
3
4
5
6
7
Big_2
PHE79[N]
ALA84[N]
GLY75[O]
ASN77[O]
ASN77[O]
ALA82[O]
GLY75[O]
Bond Length
3.1
2.7
3.6
3.1
3.1
3.1
3.1
CD
ALA398[O]
ASN400[OD1]
ASN400[N]
ASN400[N]
ASN400[ND2]
ASN400[ND2]
ARG401[N]