1
Text S2. Detailed description of galactoside, fructoside, xylose, and rhamnoside
2
degradation as encoded on poribacterial genomes.
3
Galactoside degradation
4
The poribacterial genomes encoded for several enzymes involved in galactoside
5
degradation (Fig. S5). Genes encoding for galactonate dehydratase (EC: 4.2.1.6)
6
and 2-dehydro-deoxyphosphogalactonate aldolase (EC: 4.1.2.21) were present in
7
SAGs 3G, 4C, and 4E in multiple copies (Table S5). This led to the assumption of
8
galactonate as a carbon source for Poribacteria. Further, lactose and melibiose might
9
be degraded either directly or as part of oligosaccharide chains in biopolymers by
10
alpha-and beta-galactosidase (EC: 3.2.1.22, EC: 3.2.1.23). Galactokinase (EC:
11
2.7.1.6), a central enzyme of the Leloir pathway was encoded on group I genome
12
3G. However, the intermediate genes of this pathway were missing and the
13
conversion of α-D-glucose 1-phosphate to β-D-glucose 6-phosphate that is used in
14
glycolysis is not supported on any genome. Instead the intermediate products of the
15
Lelior pathway, α-D-glucose 1-phosphate and UDP-D-galactose, are more likely to
16
be converted to UDP D-glucose via UDP-glucose-4-epimerase (EC: 5.1.3.2) or UDP-
17
glucose pyrophosphorylase (EC: 2.7.7.9), which are encoded on several poribacterial
18
genomes.
19
phosphofructokinase (EC: 2.7.1.11) or fructose bisphophate aldolase (EC: 4.1.2.13)
20
two major enzymes of glycolysis in the phylotype represented by group I, as β-D-
21
glucose 6-phosphate is usually degraded by these enzymes in glycolysis.
These
findings
are
in
accordance
with
the
absence
of
22
23
Fructoside degradation
24
Genes encoding for fructoside degrading enzymes were found on genomes 3G and
1
25
4E. Group I genome 3G encodes for a levanase (EC: 3.2.1.65), a beta-
26
fructofuranosidase (EC: 3.2.1.26), and a fructokinase (EC: 2.7.14). The beta-
27
fructofuranosidase gene is also found on genome 4E. This observation points
28
towards fructose polymers as another carbon source for Poribacteria (Fig. S6).
29
Fructoside polymers containing levan or sucrose can be of bacterial or plant origin
30
(e.g. Arvidson et al 2006, Duran and Pontis 1977, Kasapis et al 1994, Visnapuu et al
31
2011) and might be available in the sponge mesohyl through the feeding activities of
32
the sponge host or through the metabolic activities of other symbionts.
33
34
Xylose degradation
35
Genes for the two enzymes of the xylose isomerate pathway, xylose isomerase (EC:
36
5.3.1.5) and xylulokinase (EC: 2.7.1.17) were found in double copies on group I
37
genome 3G. Xylulokinase (EC: 2.7.1.17) was also discovered in double copies on
38
genome 4E. The product of this pathway, D-xylulose-5-phophate, is used in the
39
pentose phosphate pathway (Fig. S6). Genome 4E also encodes for a potential D-
40
xylonate dehydratase (EC: 4.2.1.82), which is one enzyme of the oxidative
41
conversion of xylose to 2-oxoglutarate that is used in the TCA cycle. Xylose transport
42
may be conferred via a D-xylose ABC transporter (xylF), which is encoded on group I
43
genome 3G (Table S5, S6). Xylose occurs in oligo- and polysaccharides of
44
eukaryotic and prokaryotic organisms (Singh et al 2013, Sutherland 1985).
45
46
Rhamnoside degradation
2
47
Poribacterial genomes also encode for parts of rhamnoside degradation pathways
48
(Fig. S7). Oxidative L-rhamnose was well supported through the presence of several
49
genes encoding for enzymes of this pathways in multiple copies (Table S5). L-
50
rhamnose mutarotase gene was found on genomes 3G, 4C, and 4E. L-rhamnonate
51
dehydratase (EC: 4.2.1.90) is also encoded on these genomes in double copies on
52
group I genomes, 4C, and four copies on 4E. We further detected a gene encoding
53
for 2-dehydro-3-deoxy-L-rhamnonate aldolase (EC: 4.2.1.-) on 3G, which is the last
54
enzyme in the degradation pathway from rhamnose to lactalaldehyde and pyruvate
55
(Fig. S7). A manual search for L-rhamnose dehydrogenase (EC: 1.1.1.173) and L-
56
rhamnonolactonase (EC: 3.1.1.65)revealed the presence of homologs on group I
57
(3G) and 4E to gene LRA2 encoding for L-rhamnonolactonase. Additionally Group I
58
genome 3G and genome 4E encode each for a different enzyme of the L-rhamnose
59
isomerase pathway, 3G for L-rhamnose isomerase (EC: 5.3.1.14) and 4E for
60
rhamnulokinase (EC: 2.7.1.5). Because this pathway is not complete, it is uncertain
61
whether rhamnose degradation via phosphorylated intermediates is truly part of the
62
genomic potential of Poribacteria. L-Rhamnose can be found in glycolipids and
63
glycosides especially in bacteria and plants (e.g. Karnjanapratum et al 2012, Ray et
64
al 2011, Rehm 2010) and is most likely available in the sponge matrix.
65
66
67
Arvidson SA, Rinehart BT, Gadala-Maria F (2006). Concentration regimes of
solutions of levan polysaccharide from Bacillus sp. Carbohyd Polym 65: 144-149.
68
69
70
71
Duran WR, Pontis HG (1977). Sucrose metabolism in green algae. I. The presence
of sucrose synthetase and sucrose phosphate synthetase. Molecular and Cellular
Biochemistry 16: 149-152.
72
3
73
74
75
Karnjanapratum S, Tabarsa M, Cho M, You S (2012). Characterization and
immunomodulatory activities of sulfated polysaccharides from Capsosiphon
fulvescens. Int J Biol Macromol 51: 720-729.
76
77
78
79
80
Kasapis S, Morris ER, Gross M, Rudolph K (1994). Solution Properties of Levan
Polysaccharide from Pseudomonas-Syringae Pv Phaseolicola, and Its Possible
Primary Role as a Blocker of Recognition during Pathogenesis. Carbohyd Polym 23:
55-64.
81
82
83
84
Ray B, Bandyopadhyay SS, Capek P, Kopecký J, Hindák F, Lukavský J (2011).
Extracellular glycoconjugates produced by cyanobacterium Wollea saccata.
International Journal of Biological Macromolecules 48: 553-557.
85
86
87
Rehm BHA (2010). Bacterial polymers: biosynthesis, modifications and applications
8: 578-592.
88
89
90
91
Singh RP, Shukla MK, Mishra A, Reddy CR, Jha B (2013). Bacterial extracellular
polymeric substances and their effect on settlement of zoospore of Ulva fasciata.
Colloids Surf B Biointerfaces 103: 223-230.
92
93
94
Sutherland IW (1985). Biosynthesis and composition of gram-negative bacterial
extracellular and wall polysaccharides. Annu Rev Microbiol 39: 243-270.
95
96
97
98
99
Visnapuu T, Mardo K, Mosoarca C, Zamfir AD, Vigants A, Alamae T (2011).
Levansucrases from Pseudomonas syringae pv. tomato and P. chlororaphis subsp.
aurantiaca: substrate specificity, polymerizing properties and usage of different
acceptors for fructosylation. J Biotechnol 155: 338-349.
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