Biology Reference
In-Depth Information
Table 6.3 Sequence identity of the TrHb1s considered in this chapter
N. com.
GlbN
N. pun.
TrHb1-1
N. pun.
TrHb1-2
S. 7002
GlbN
S. 6803
GlbN
CtrHb
THB1
N. com.
GlbN
1
N. pun.
TrHb1-1
96%
113/118
1
N. pun.
TrHb1-2
29%
35/122
31%
38/122
1
S.
7002
GlbN
30%
36/119
31%
37/119
25%
30/119
1
S.
6803
GlbN
40%
40/100
41%
41/100
31%
33/106
60%
74/124
1
CtrHb
33%
39/118
33%
39/118
27%
22/120
47%
57/122
45%
55/122
1
THB1
37%
44/118
36%
43/118
27%
34/124
46%
52/114
49%
53/109
48%
55/114
1
N. com.
GlbN,
Nostoc commune
UTEX 584 GlbN (Q00812);
N. pun.
TrHb1-1,
Nostoc punctiforme
ATTC
29133 TrHb1-1 (B2J6Y7);
N. pun.
TrHb1-2,
Nostoc punctiforme
strain ATTC 29133TrHb1-2 (B2IV60);
S.
7002 GlbN,
Synechococcus
sp. strain PCC 7002 GlbN (Q8RT58);
S.
6803 GlbN,
Synechocystis
sp. strain
PCC 6803 GlbN (P73925); CtrHb,
Chlamydomonas eugametos
LI637 Hb (Q98753), haem domain;
THB1,
Chlamydomonas reinhardtii
THB1 (A8JAR4).
5.1.4 Synechococcus sp. strain PCC 7002 GlbN
The level of identity between
Synechococcus
7002 GlbN and
Synechocystis
6803 GlbN is modest (60%,
Table 6.3
) but the main features of bis-histidine
coordination in the absence of exogenous ligand and the alkylation of
His117 by the haem group are conserved. Optical data are similar to those
of the
Synechocystis
protein (
Scott et al., 2002
;
Table 6.2
). The three-
dimensional structure of the posttranslationally modified protein has been
solved by both NMR spectroscopy and X-ray crystallography. The differ-
ences noted in the case of
Synechocystis
6803 GlbN, specifically the greater
flexibility of the EF loop and the variable position of the A helix relative
to the rest of the protein, are also observed in this TrHb1.
A study of backbone dynamics assessed by
15
NNMR relaxation provides
a complementary view of GlbN in solution (
Pond, Majumdar, & Lecomte,
2012
). This method is well suited for comparative purposes, and six different
states were inspected (
Table 6.4
). In all cases, the structure is rigid on the
