Suzuki A, Shibata N, Suzuki M, Saitoh F, Takata Y, Oshie A, Oyamada H, Kobayashi H, Suzuki S, Okawa Y
Second Department of Hygienic Chemistry, Tohoku College of Pharmacy, Miyagi, Japan.
Eur J Biochem. 1996 Aug 15;240(1):37-44. doi: 10.1111/j.1432-1033.1996.0037h.x.
A particulate insoluble fraction from Candida albicans NIH B-792 (serotype B) strain cells was obtained as the residue after extracting a 105000 x g pellet of cell homogenate with 1% Triton X-100. Incubation of this fraction with a mannopentaose, Man alpha 1-->3Man alpha 1-->2Man alpha 1-->Man alpha 1-->2Man, in the presence of GDP-mannose and Mn2+ at pH 6.0 gave a branched mannohexaose, [sequence: see text] 6 the structure of which was identified by means of sequential off assignment. However, the enzyme fraction obtained from Candida parapsilosis gave Man alpha 1-->2Man alpha 1-->3Man alpha 1-->2Man alpha 1-->2 Man alpha 1-->2Man under the same conditions. These results demonstrate the finding that the structural difference in the mannans of these two species is due to the presence of alpha-1.6-linked branching mannose units in the C. albicans mannan [Shibata, N., Ikuta, K., Imai, T., Satoh, Y., Satoh, R., Suzuki, A., Kojima, C., Kobayashi, H., Hisamichi, K. & Suzuki, S. (1995) J. Biol. Chem. 270, 1113-1122]. The substrate-specificity study of the enzyme indicated that the structural requirement of the alpha-1,6-mannosyltransferase is Man alpha 1-->3Man alpha 1-->. The alpha-1,6-mannosyltransferase also transferred the alpha-1,6-linked branching mannose unit to the mannan of Saccharomyces cerevisiae. The transformation of the mannan was detected by the appearance of antigenic factor 4 using an enzyme-linked immunosorbent assay and two-dimensional homonuclear Hartmann-Hahn spectroscopy.
白色念珠菌NIH B - 792（血清型B）菌株细胞的颗粒不溶部分是在用1% Triton X - 100提取细胞匀浆105000 x g沉淀后的残余物。在pH 6.0条件下，该部分与甘露五糖（Manα1→3Manα1→2Manα1→Manα1→2Man）在GDP - 甘露糖和Mn²⁺存在下孵育，得到一种分支甘露六糖，[序列：见原文]6，其结构通过顺序去分配得以鉴定。然而，近平滑念珠菌获得的酶部分在相同条件下产生Manα1→2Manα1→3Manα1→2Manα1→2Manα1→2Man。这些结果表明，这两个物种甘露聚糖的结构差异是由于白色念珠菌甘露聚糖中存在α - 1,6 - 连接的分支甘露糖单元[柴田，N.，生田，K.，今井，T.，佐藤，Y.，佐藤，R.，铃木，A.，小岛，C.，小林，H.，久见，K. & 铃木，S.（1995年）《生物化学杂志》270，1113 - 1122]。对该酶的底物特异性研究表明，α - 1,6 - 甘露糖基转移酶的结构要求是Manα1→3Manα1→。α - 1,6 - 甘露糖基转移酶还将α - 1,6 - 连接的分支甘露糖单元转移到酿酒酵母的甘露聚糖上。通过酶联免疫吸附测定和二维同核Hartmann - Hahn光谱法利用抗原因子4的出现检测到甘露聚糖的转化。
