23216604, FEBS J. 2013 Feb;280(3):950-64. doi: 10.1111/febs.12089. Epub 2013 Jan 7.

Characterization method

enzyme activity assay

Genomic accession number


Nucelotide position range







Geobacillus stearothermophilus/1422

Degradation or Biosynthesis


Gene Name

Locus Tag

Protein ID

Gene Position

GenBank Contig Range

EC Number

mcp - AEH26457.1 80 - 1775 (-) JF327803.1:160-1855 -
ganR - AEH26451.1 2378 - 3371 (+) JF327803.1:2458-3451 -
ganE - AEH26452.2 3492 - 4782 (+) JF327803.1:3572-4862 -
ganF - AEH26453.2 4956 - 6213 (+) JF327803.1:5036-6293 -
ganG - AEH26454.1 6216 - 7068 (+) JF327803.1:6296-7148 -
ganB - AEH26455.1 7087 - 9151 (+) JF327803.1:7167-9231
ganA - AEH26456.2 9279 - 11724 (+) JF327803.1:9359-11804

Cluster number


Gene name

Gene position

Gene type

Found by CGCFinder?

- 81 - 1775 (-) TC: gnl|TC-DB|M3JA40|1.B.52.2.1 Yes
- 2379 - 3371 (+) TF: DBD-Pfam|LacI,DBD-SUPERFAMILY|0044558 Yes
- 3493 - 4782 (+) TC: gnl|TC-DB|O07009|3.A.1.1.2 Yes
- 4957 - 6213 (+) TC: gnl|TC-DB|O32261|3.A.1.1.2 Yes
- 6217 - 7068 (+) TC: gnl|TC-DB|O07011|3.A.1.1.2 Yes
- 7091 - 9151 (+) CAZyme: GH42 Yes
- 9280 - 11724 (+) CDS No




23216604, FEBS J. 2013 Feb;280(3):950-64. doi: 10.1111/febs.12089. Epub 2013 Jan 7.


Functional characterization of the galactan utilization system of Geobacillus stearothermophilus.


Tabachnikov O, Shoham Y


Type I galactan is a pectic polysaccharide composed of beta-1,4 linked units of d-galactose and is part of the main plant cell wall polysaccharides, which are the most abundant sources of renewable carbon in the biosphere. The thermophilic bacterium Geobacillus stearothermophilus T-6 possesses an extensive system for the utilization of plant cell wall polysaccharides, including a 9.4-kb gene cluster, ganREFGBA, which encodes galactan-utilization elements. Based on enzyme activity assays, the ganEFGBA genes, which probably constitute an operon, are induced by short galactosaccharides but not by galactose. GanA is a glycoside hydrolase family 53 beta-1,4-galactanase, active on high molecular weight galactan, producing galactotetraose as the main product. Homology modelling of the active site residues suggests that the enzyme can accommodate at least eight galactose molecules (at subsites -4 to +4) in the active site. GanB is a glycoside hydrolase family 42 beta-galactosidase capable of hydrolyzing short beta-1,4 galactosaccharides into galactose. Applying both GanA and GanB on galactan resulted in the full degradation of the polymer into galactose. The ganEFG genes encode an ATP-binding cassette sugar transport system whose sugar-binding lipoprotein, GanE, was shown to bind galacto-oligosaccharides. The utilization of galactan by G. stearothermophilus involves the extracellular galactanase GanA cleaving galactan into galacto-oligosaccharides that enter the cell via a specific transport system GanEFG. The galacto-oligosaccharides are further degraded by the intracellular beta-galactosidase GanB into galactose, which is then metabolized into UDP-glucose via the Leloir pathway by the galKET gene products. DATABASE: Nucleotide sequence data have been deposited in the GenBank database under the accession number JF327803.