The Schizosaccharomyces pombe endo-1,3-beta-glucanase Eng1 contains a novel carbohydrate binding module required for septum localization.
Cell separation in Schizosaccharomyces pombe is achieved through the concerted action of the Eng1 endo-beta-1,3-glucanase and the Agn1 endo-alpha-1,3-glucanase, which are transported to the septum and localize to a ring-like structure that surrounds the septum. Correct localization of these hydrolases requires the presence of both the septins and the exocyst. In this work, we show that the glucanase Eng1 contains a region at the C-terminus that acts as a carbohydrate-binding module (CBM) and that it is not present in other members of glycoside hydrolases family 81 (GH81). In vitro, the purified CBM has affinity for beta-1,3-glucan chains with a minimum degree of polymerization of 30 glucose units. Deletion of the CBM results in a protein that is largely defective in complementing the separation defect of eng1Delta mutants. This defect is due to a reduction in the catalytic activity against insoluble substrates and to a defect in targeting of Eng1 to the septum, as the truncated protein localizes to the lateral cell wall of the cell. Thus, the targeting of Eng1 to the primary septum requires not only trans-factors (septins and the exocyst complex) but also a cis-element localized to the C-terminus of the protein.
Martín-Cuadrado
Ana Belén
AB
Instituto de Microbiología Bioquímica, Dpto. Microbiología y Genética, CSIC/Universidad de Salamanca, Campus Miguel de Unamuno 37007, Salamanca, Spain.
Encinar del Dedo
Javier
J
de Medina-Redondo
María
M
Fontaine
Thierry
T
del Rey
Francisco
F
Latgé
Jean Paul
JP
Vázquez de Aldana
Carlos R
CR
D000595:Amino Acid Sequence; D050260:Carbohydrate Metabolism; D002455:Cell Division; D002473:Cell Wall / Q000737:chemistry* / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D017124:Conserved Sequence; D004693:Glucan Endo-1,3-beta-D-Glucosidase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D012568:Schizosaccharomyces / Q000737:chemistry* / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D029702:Schizosaccharomyces pombe Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment
D029702:Schizosaccharomyces pombe Proteins; D004693:Glucan Endo-1,3-beta-D-Glucosidase