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mitochondrial assimilation, and TrHbs were acquired later as the result of
the chloroplast assimilation.
All of this can be seen to play out within the phylogenetic tree shown in
Fig. 6.3
. The bottom of the tree groups the M family globins, and the top
portion of the tree groups proteins from the T family. The exception to this
is a small grouping of two proteins (seen at the very bottom of the tree dia-
gram). These two proteins (Uniprot E1ZBP8 and E1ZF79, both from the
genome of
Chlorella
sp. NC64A) clearly segregate from both portions of the
phylogenetic tree. Previous analysis of these predicted proteins by
Vinogradov, Fernandez, et al. (2011)
has determined that they are related
to TrHb2-type globins. Two other eukaryotic hypothetical proteins are
predicted to be TrHb2 globins (Uniprot identifier E1Z454 from
Chlorella
sp. NC64A, and A8J8P3 from
C. reinhardtii
), but in
Fig. 6.3
, both of these
proteins cluster within the TrHb1 proteins, as noted in the phylogenetic
analysis by
Vinogradov, Fernandez, et al. (2011)
.
The remainder of the proteins within the top portion of the tree are all
TrHb1 globins. Interspersed within this section are the GlbN proteins from
N. commune
(Uniprot ID Q00812),
Nostoc punctiforme
(Uniprot ID B2J6Y7),
Synechococcus
sp. PCC7002 (Uniprot IDQ8RT58), and
Synechocystis
sp. PCC
6803 (Uniprot ID P73925), and the LI637 protein from
C. eugametos
(Uni-
prot ID Q08753). The eukaryotic TrHb1s cluster together into two smaller
groups (eukaryote proteins identified by small black diamond) with the
exception of one protein from
Volvox carteri
(Uniprot ID D8TWR5)
that clusters with a group of TrHb1 proteins from three different species
of the Cyanobacteria
Nostoc
. The significance of this cluster is unknown,
but given the simplistic approach used to generate this figure, further anal-
ysis would be required in order to speculate. A small cluster also forms
around the TrHb1 protein from
N. punctiforme
(Uniprot ID B2IV60),
known to belong to the subgroup TrHb1-2. The four proteins
(K9UL54, K9WZP6, D8G8J5, K9VF25) that cluster with the TrHb1-2
from
N. punctiforme
were subsequently aligned and found to possess attri-
butes of TrHb1-2 (
Fig. 6.7
).
The globins of cyanobacteria and green algae fall mostly within the
grouping of TrHb1-1 and SDgb type globins, with a few TrHb1-2, TrHb2
and recently added SSDgb examples. In
Section 4
, we examine what phys-
iological information exists for these globins. Although we are constantly
increasing the genomic information available for expanding our phyloge-
netic classification of these proteins and making great strides in that domain,
the physiologic research conducted on cyanobacterial and algal globins is
