β(1,3)-glucanosyl-transferase activity is essential for cell wall integrity and viability of Schizosaccharomyces pombe.
BACKGROUND
The formation of the cell wall in Schizosaccharomyces pombe requires the coordinated activity of enzymes involved in the biosynthesis and modification of β-glucans. The β(1,3)-glucan synthase complex synthesizes linear β(1,3)-glucans, which remain unorganized until they are cross-linked to other β(1,3)-glucans and other cell wall components. Transferases of the GH72 family play important roles in cell wall assembly and its rearrangement in Saccharomyces cerevisiae and Aspergillus fumigatus. Four genes encoding β(1,3)-glucanosyl-transferases -gas1(+), gas2(+), gas4(+) and gas5(+)- are present in S. pombe, although their function has not been analyzed.


RESULTS
Here, we report the characterization of the catalytic activity of gas1p, gas2p and gas5p together with studies directed to understand their function during vegetative growth. From the functional point of view, gas1p is essential for cell integrity and viability during vegetative growth, since gas1Δ mutants can only grow in osmotically supported media, while gas2p and gas5p play a minor role in cell wall construction. From the biochemical point of view, all of them display β(1,3)-glucanosyl-transferase activity, although they differ in their specificity for substrate length, cleavage point and product size. In light of all the above, together with the differences in expression profiles during the life cycle, the S. pombe GH72 proteins may accomplish complementary, non-overlapping functions in fission yeast.


CONCLUSIONS
We conclude that β(1,3)-glucanosyl-transferase activity is essential for viability in fission yeast, being required to maintain cell integrity during vegetative growth.
Departamento de Microbiología y Genética, Instituto de Microbiología Bioquímica, Consejo Superior de Investigaciones Científicas, Universidad de Salamanca, Salamanca, Spain.
María
M
de Medina-Redondo
Yolanda
Y
Arnáiz-Pita
Cécile
C
Clavaud
Thierry
T
Fontaine
Francisco
F
del Rey
Jean Paul
JP
Latgé
Carlos R
CR
Vázquez de Aldana
D055162:Biocatalysis; D015152:Blotting, Northern; D002453:Cell Cycle / Q000235:genetics / Q000502:physiology; D002455:Cell Division / Q000235:genetics / Q000502:physiology; D002473:Cell Wall / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D004693:Glucan Endo-1,3-beta-D-Glucosidase / Q000235:genetics / Q000378:metabolism*; D005936:Glucans / Q000378:metabolism; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008856:Microscopy, Fluorescence; D008858:Microscopy, Phase-Contrast; D009154:Mutation; D012568:Schizosaccharomyces / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics / Q000378:metabolism*
D005936:Glucans; D007527:Isoenzymes; D008164:Luminescent Proteins; D029702:Schizosaccharomyces pombe Proteins; C117939:1,3-beta-glucanosyltransferase; D004693:Glucan Endo-1,3-beta-D-Glucosidase