Table 2.

Conservation of key residues in the sequences of each SSN meta-node. The proven activities are rendered in bold type. The presence of sequences with a signal peptide in each meta-node is also indicated. The reference sequences for mannoside-phosphorylases and mannosidases are ADD61463.1 [β-1,4-mannosyl-N,N’-diacetylchitobiose-phosphorylase (20)] and AAO78885.1 [β-1,2-mannosidase (12)], respectively. Both enzymes are functionally and structurally characterized. In meta-node C3, a signal peptide was detected for the characterized members ALJ48509.1 and ACT94389.1, but not for AAO78885.1

Meta-node	Number of full-length sequences CAZy/metagenomes/total		Sequences with signal peptide	Catalytic residues		Phosphate-binding residues		+1 subsite				Predicted mechanism and linkage specificity
				Proton donor	Putative base
C1	221/836/1057		No	D	_	R	H	R	Y	R	D	GPs-β-1–4
C2 ADD61463.1	268/757/1025		No	D D104	_	R R168	H H231	R R59	Y Y103	R R150	D D304	GPs-β-1–4
C3 AAO78885.1	113/152/265		Yes	D D142	D/E E227	_	_	R R89	E E141	K K199	D D363	GHs-β-1–2
C4	290/76/366	295/366	No	D	_	R	H	R	E	K	D	GPs-β-1–2
		70/366						R	E	R	D	GPs-β-1–3
C5	42/70/112		No	D	_	R	H	R	E	R	D	GPs-β-1–3
C6	85/0/85		No	D	_	R	H	R	E	K	D	GPs-β-1–2
UC1	31/66/97		No	D	_	R	H	R	Y	R	D	GPs-β-1–4
UC2	199/0/199		No	D	_	R	H	R	E	K	D	GPs-β-1–2
UC3	135/18/153	124/153	No	D	_	R	H	R/D	E	K	D	GPs-β-1–2
		7/153						R/D	E	R	D	GPs-β-1–3
		14/153						R/D	Y	R		GPs-β-1–4
UC4	0/53/53		Yes	_	_	_	_	S	M	N	_	GHs
UC5	61/0/61		No	D	_	R	H	R	E	K	D	GPs-β-1–2
UC6	0/11/11		No	D	_	R	H	R	I	R	D	GPs
UC7	9/10/19		No	D	_	R	H	R	E	R	D	GPs-β-1–3
UC8	26/7/33		No	D	_	R	H	R	E	K	D	GPs-β-1–2
UC9	29/0/29		No	D	_	R	H	R	E	K	D	GPs-β-1–2